Cyclic compaction systems for polishing of gears and other materials

Abstract

The invention of cyclic compaction systems represents a significant advancement in the field of metal smoothing and polishing, particularly for complex geometries and irregular surfaces. This innovative approach involves assemblies, systems, and methods that utilize a cyclic compressing mechanism combined with ion transport dry electrolytes. This mechanism facilitates the compaction of free solid bodies, enhancing the electrical current across the surface being polished. Cyclic compaction systems are particularly effective for polishing challenging-shaped samples such as gears, inner channels, punches and concave surfaces as they enable precise control over the polishing process. Various configurations of these systems can be adapted to meet specific requirements, ensuring optimal results based on the unique characteristics of the workpieces involved. By adjusting parameters such as particle layer thickness, pump suction force, rotational frequencies, and electrolyte composition, the systems can achieve significant improvements in surface quality and reduction in roughness values.

Description

[0001] CYCLIC COMPACTION SYSTEMS FOR POLISHING OF GEARS AND OTHER MATERIALS

[0002] FIELD OF APPLICATION OF THE INVENTION

[0003] The present disclosure relates to the field of surface finishing. More particularly, the disclosure relates to assembly systems, prototypes, methods, and electrolytes for surface finishing objects and objects with surfaces polished by such methods. More specifically, it represents a relevant improvement regarding the homogeneity, final roughness, and control of the polishing process using free solid particle electrolytes, an enhancement in the anticorrosive properties obtained, and an increase in the lifespan of the polishing medium.

[0004] BACKGROUND OF THE INVENTION

[0005] Various surface finishing technologies, including electropolishing (also known as electrochemical polishing, anodic polishing, or electrolytic polishing), are widely used to remove material from workpieces, typically metallic, by applying a specific voltage that is particularly high at the edges or tips. This type of method usually involves immersing a metal part in an electrolyte bath and applying an electric potential difference to polish the surface. Some methods utilize electrically conductive particles, as detailed in International Application No. PCT / ES2017 / 070247 (published as WO 2017 / 186992 A1), which describes a method for smoothing and polishing metals via ion transport using electrically conductive free solid bodies, and International Application No. PCT / ES2021 / 070065 (published as WO 2022 / 123096 A1), which discusses treating metallic surfaces using an electrolytic medium comprising solid particles and a non- conductive fluid.

[0006] Despite these advancements, several challenges persist. A significant issue is controlling the relative movement between free solid bodies and the metal surface being treated. Complex geometries can hinder free solid bodies from effectively reaching all surfaces, particularly concave surfaces and inner channels, resulting in an uneven finish. Existing mechanical methods for providing relative motion between particles and the treated surface lack the precision required for complex geometries or fine control of surface roughness.

[0007] Additionally, defects can arise when electrically conductive free solid bodies remain stationary in contact with the metal surface, leaving projection marks. This issue is more pronounced in areas with limited access for relative particle movement. The chaotic nature of fluid dynamics during polishing can lead to unpredictable particle movements, causing undesirable results such as oxidation due to insufficient particle pressure in turbulent zones. Ensuring adequate pressure between electrically conductive free solid bodies and the surface is critical for effective electrical field connection, preventing electrical isolation between the anode and cathode.

[0008] Electrically conductive free solid bodies incorporating ion exchange resin also face material removal capacity limits due to resin saturation. The lifespan of these solid bodies is determined by the metal ion absorption kinetics of the resin, with reaction kinetics becoming insufficient below a certain saturation level, leading to poor surface results. Enhancing the homogeneity of anticorrosive properties provided to the treated surfaces is also challenging in dry electropolishing processes compared to conventional electrochemical methods.

[0009] A limit exists on the material removal capacity of a set of electrically conductive free solid bodies containing an ion exchange resin. This limit of maximum capacity is reached when the metal ions fully saturate all the free reactive radicals in the resin's chemical structure. However, the lifespan of the resin does not only rely on this maximum capacity as the absorption kinetics of the metal ions by the resin also takes part on it. When the saturation level it is not still in the maximum capacity, the reaction kinetics between the resin and the metal ions may become insufficient to maintain the necessary conditions for effective electropolishing, leading to suboptimal surface results.

[0010] Several projection systems use electrically conductive free solid bodies as the ion transport element for material removal during surface treatment. International Application No. PCT / ES2020 / 070499 (published as WO 2021 / 019121 A1), International Application No. PCT / ES2021 / 070864 (published as WO 2022 / 123096 A1) and International Application No. PCT / ES2023 / 070675 (published as WO 2024 / 105293 A1) outline a method for smoothing and polishing metals via ion transport using electrically conductive free solid bodies, a method for smoothing and polishing metals via ion transport using electrically conductive free solid bodies including a non-conductive fluid on its environment and a method for smoothing and polishing metals via ion transport using electrically conductive free solid bodies in a projection system. These projection methods, assemblies, and systems present limitations on electrical conductivity through the projected electrically conductive free solid bodies between the cathode and the anode and the packing factor of the projected solid bodies. There are significant constraints on the projection flow, speed, and the distance from the nozzle to the metal surface to ensure electrical contact.

[0011] The packing factor is defined as the ratio between the volume occupied by solid particles and the total volume of the system in which those particles are contained. It quantitatively represents how efficiently the available space is filled by the solid material.

[0012] In complex geometries and depending on the applied relative movement and the orientation between the surface to be treated and the solid bodies, insufficient contact defects attributed to a lack of galvanic action are to be found under certain aerodynamic conditions, such as sota-vento surfaces, i.e. , downwind surfaces. The previously existing systems including a non- conductive fluid on the solid bodies environment, makes it difficult to achieve a homogeneous surface treatment under the previously mentioned conditions. The higher mobility of the liquid phase present on the environment has a faster occupying dynamic of turbulent domains, which decreases the packing factor and pressure between solid bodies and between the solid bodies and the surface to be polished.

[0013] There are systems based on cyclic compaction used as surface finishing processes. These systems rely on a combination of mechanical and chemical actions to achieve high-quality surface finishes. The polishing mediums use some additive components for a significant enhancement of the polishing process. However, any cyclic compaction system based on electrically conductive solid bodies have been used to promote the polishing efficiency under the working conditions of a surface treatment.

[0014] International Application No. PCT / US2020 / 035487 (published as WO 2021 / 019121 A1) and PCT / JP2019 / 028912 (published as WO 2021 / 019121 A1) details the use of carboxylic acids, glycols or alcohols as additives in electrolytes. These additives help in forming a protective layer on the surface of the parts being treated. This protective layer improves the homogeneity of the surface finish all over the treated part but also present some heterogeneities under certain polishing conditions depending on its geometry and aerodynamic shape.

[0015] Both patents propose the addition of various components to electrolytes, including carboxylic acids, saturated fatty acids, glycols and alcohols. Glycols, such as ethylene glycol and propylene glycol, are used for their ability to protect the metal sample of the electrolyte solution. Alcohols, like ethanol or isopropanol, assist in improving also the protection of the metal surface generating a resistive protective layer and ensures that the electrolyte spreads evenly across the surface. Saturated fatty acids, such as octanoic acid, contribute to the formation of a lubricating layer that reduces friction during the polishing process.

[0016] Despite these advancements, the electrolytes formulated with these components still exhibit limitations when it comes to polishing complex geometries. Intricate surfaces, such as concave areas, grooves, gear teeth, and the interiors of ducts, pose significant challenges. The difficulty lies in ensuring that the electrolyte can effectively act on these intricate areas and perform the wanted results for a good polishing there. The irregular shapes and limited accessibility of these geometries prevent the uniform application and action of the electrolytes, leading to uneven finishes.

[0017] Moreover, the chaotic fluid dynamics involved in polishing processes, especially in areas with limited access, can result in unpredictable movements of the particles and electrolytes. This can cause insufficient pressure and inadequate contact between the polishing medium and the surface, further complicating the achievement of a consistent and high-quality finish.

[0018] In various industries, numerous particles compacting systems are employed for a wide range of applications; however, these systems have never been considered within the electropolishing industry.

[0019] Regarding the gears themselves, their finish characteristics, particularly in terms of surface roughness, are crucial for their performance and durability. Different parts of the gear, such as the flanks, roots, and faces, have specific roughness requirements based on their functions. Proper finishing ensures smooth operation, reduces wear, and extends the service life of gears in various industrial applications.

[0020] In a gear system, several key components contribute to its overall functionality, including a face, a crest, a flank, and a valley. A face (500) refers to a flat surface of a gear teeth, while a crest (501) is the topmost point of a gear tooth. A flank (502) is a critical surface for a transmission of force, as it is a sloping side of a tooth that engages with a corresponding tooth of another gear. A valley (503) is a space between two adjacent teeth, playing an essential role in accommodating movement and reducing friction.

[0021] The head circumference (504) is an outer boundary of the gear, while a primitive circumference (505) represents a theoretical circle from which a tooth profile is derived. A root circumference (506) is the lowest point of a gear tooth, and a base circumference (507) is a diameter of a circle from which a tooth profile is constructed.

[0022] The most important part of a gear to polish is the flanks of the teeth. This area is crucial because it is directly involved in contact and power transmission between meshing gears. Polishing the minimizes friction and wear, leading to smoother operation and extended gear life. Enhanced surface finish on the flanks improves load distribution and reduces the likelihood of pitting and other forms of surface fatigue, thereby increasing the gear's efficiency and durability in high-precision and high-load applications.

[0023] The article "Gulzow, B., & Uhlmann, E. (2022). Gearwheel finishing with abrasive brushing tools to improve the surface quality of tooth flanks for the industrial application. Machines, 10(12), 1220. DOI: 10.3390 / machines10121220." discusses the polishing of gears using abrasive brushing tools to enhance the surface quality of gear tooth flanks. Using S240x0.75 and S320x0.60 tools, the average surface roughness, Ra, is decreased by approximately 0.2 pm, achieving values of 0.23 pm and 0.33 pm, respectively. The process, conducted within a gear profile grinding machine, uses abrasive filaments embedded in a resin base, such as aluminum oxide or silicon carbide, ensuring a high-quality finish without affecting dimensional accuracy. The S240x0.75 tool lasts about 150 minutes, while the S320x0.60 tool lasts 40 minutes before wearing out.

[0024] There remains a gap in the development of a technique that allows for the removal of an extremely small amount of material from objects, including but not limited to gears, while ensuring that the object's (e.g., gear’s) geometry remains unchanged. Sometimes the objects feature a case-hardened layer created by heat treatment, which increases the hardness of the surface, such as cementation. This layer is very thin, and it would be cost-saving to preserve as much layer as possible during the final surface treatment. Furthermore, if a polishing process could remove a small amount and localized case-hardened layer, the overall process would be more efficient, as any potential cracks generated during hardening could be easily removed. SUMMARY OF THE INVENTION

[0025] This invention refers to a novel method aimed at achieving high quality polishing results with low final roughness for materials polished through ion transport using electrically conductive free solid bodies in complex geometries, in particular for concavities. In several particular embodiments, the method includes providing a non-conductive fluid on the environment within the solid bodies, in conjunction with cyclic compaction systems. These systems enhance the performance of the polishing mediums, leading to significant improvements in the polishing process.

[0026] The effective implementation of compacting systems, particularly in conjunction with electrically conductive free solid bodies-based electrolytes, more in particular in conjunction with ion exchange resin-based electrolytes, enables access to difficult geometries, thereby improving the overall polishing process. This capability allows for better treatment of intricate surfaces and complex shapes that are typically challenging to polish.

[0027] In the context of the present disclosure, dry electrolytes, solid-particle based electrolyte, polishing medium, electrolytic medium and electrolytes based solid particles that are conductive because they retain an electrolyte liquid, these terms mean the same and will be treated interchangeably along the description.

[0028] In the context of the present disclosure solid particles, conductive particles, solid electrolyte particles, solid bodies, electrically conductive free solid bodies, these terms mean the same and will be treated interchangeably along the description.

[0029] In the context of the present disclosure a fluid, a fluid that includes solid particles, a medium, liquid medium, environment, liquid medium environment, surrounding liquid, a medium on the interstitial space or gaps, these terms mean the same and will be treated interchangeably along the description.

[0030] The present invention, while not limited to any particular industrial application, is especially advantageous for providing surface treatment to metallic components or workpieces that exhibit complex geometries. Such geometries may include cavities with draft angles, grooves, recesses, undercuts, narrow channels, or other hard-to-access features that typically pose challenges to conventional finishing or coating techniques. The invention is also well suited for treating surfaces resulting from subtractive and additive manufacturing methods, such as machining, milling, grinding, rectifying, or 3D printing, where as-built surface quality may present irregularities or require functional enhancement.

[0031] A surface treatment according to the present invention encompasses a controlled process that induces targeted modifications of the surface properties of a workpiece. These modifications may include improvements in tribological behavior (such as friction reduction and wear resistance), enhancement of mechanical integrity (including fatigue resistance and load-bearing capacity), adjustment of surface roughness and topography, as well as controlled alteration of the chemical composition or reactivity of the outermost surface layer. Such transformations can be achieved selectively and uniformly even on areas of the component that are difficult to reach by conventional methods, thereby extending the functional lifetime and performance of the treated part.

[0032] The cyclic compaction systems for dry electropolishing systems (CCDEP) consist on methods, systems and assemblies or apparatuses configured to change the stationary packing factor or the pressure between the solid bodies conforming a dry electropolishing system, in order to achieve a better control on the conditions under which the solid bodies reach the challenging surface to be polished. The working efficiency and obtained final result over the treated surface of mentioned systems is highly impacted by the pressure, packing factor and mobility of the solid bodies transmitting current from the cathode and the surface to be polished. The higher the pressure and packing factor, the higher ion exchange, increasing the surface treatment speed. If there is no sufficient contact or pressure between the solid bodies and between the solid bodies and the surface to be polished, insufficient polishing results or defects, such as oxides, are found.

[0033] An aspect of the present invention includes a system for surface treating surfaces through ion transport, comprising: at least one electrically conductive device; an electrical power supply configured to provide a voltage between an anode and a cathode; an electrical connection system connecting the anode to a positive pole of the electrical power supply and the cathode to a negative pole of the electrical power supply; a fixing system configured to hold a metal part of an object with a surface to be treated to a first pole of the electrical power supply and at least one electrically conductive device to a second pole; a receptacle for holding a solid-particle based electrolyte, the at least one surface being treated and the at least one electrically conductive device; means for generating a relative movement between a surface to be treated of the metal part and the solid-particle based electrolyte when held in the receptacle; a compression system configured to compact free electrically conductive solid bodies of the solid-particle based electrolyte in contact with the surface to be treated and the at least one electrically conductive device.

[0034] In order to overcome the undesired or uneven surface treatments on the turbulent zones present on the treatment of parts comprising a complex geometry, such as a concave surface, a system or method to force the particles to be compacted on said area, increases the achieved polishing quality.

[0035] In some embodiments, the system further includes the metal part and the surface to be treated. That is, the system further includes an object with the metal part and including at least one surface to be treated.

[0036] In some embodiments, the system further includes the solid-particle based electrolyte comprising free electrically conductive solid bodies and a fluid.

[0037] In some embodiments, the means for generating the relative movement comprises: a movable receptacle including means for linear or rotational movement; one or more arms to hold the workpiece or workpieces, allowing vertical, longitudinal, or circular motion; and one or more cathode systems, that move in at least one axis, including vertical, or longitudinal, or rotational movement while the sample remains fixed.

[0038] In the present invention the packing factor is understood as the ratio between the volume of a solid-particle based electrolyte that is occupied by a volume of solid particles. Thereby, the packing factor is PF = — = — — — < 1 where VTcorresponds to an arbitrary volume of a solid- particle based electrolyte below the surface delimiting the solid particle bed, Vsis the volume occupied by solid particles within that VTand VFcorresponds to the free volume left within that VT. In particular embodiments of the invention, the free volume VFwithin a compacting cycle is decreased between 60% and 1 % with respect to its original fraction (wherein the original fraction is understood as the PF in static conditions), particularly between 5% and 30 %, more in particular between 10% and 20%.

[0039] The static, or at rest, conditions of the solid-particle based electrolyte refer to the state of the system in which no significant electrical potential, current flow, or active compaction is applied. Under these conditions, the electrolyte, solid particles, and treated surface remain substantially static, with the system being in mechanical and electrochemical equilibrium and no intentional surface treatment taking place. In contrast, the working conditions correspond to the operational state of the system in which electrochemical and mechanical parameters are actively controlled through a compacting mechanism. During such working conditions, the compacting system acts to reduce the free volume within the solid-particle based electrolyte, thereby increasing the packing factor and promoting controlled interaction between the solid particles and the surface to be treated.

[0040] In particular embodiments of the invention, the pressure is increased within a compaction cycle with respect to the static conditions experienced by an area of the surface being treated. In some cases, the pressure is increased between a 10 % and a 1000 % with respect to its original value, in particular between 20 % and 100%, more in particular between 30 % and 50%.

[0041] In particular embodiments of the invention, the current density is increased within a compaction cycle with respect to static conditions experienced by an area of the surface being treated. In some cases, the pressure is increased between a 10 % and a 100 % with respect to its original value, in particular between 20 % and 70 %, more in particular between 30 % and 50%. In particular embodiments of the invention, the time period of a compaction cycle experienced by an area of the surface being treated with respect to the overall polishing time can be varied within the process. In some cases, period of a compaction cycle experienced by an area of the surface being treated ranges between a 0.001 % and a 20 % with respect to the overall polishing time, in particular between 0.01 % and 1 %, more in particular between 0.01 % and 0.1 %.

[0042] In particular embodiments of the invention, the duration of a compaction cycle is defined as the time interval during which the packing factor and / or the pressure within the solid-particle based electrolyte vary from a first minimum value to a maximum value and subsequently decrease to a second minimum value before the next increase begins. Said minimum and maximum values may correspond to either local or global extremes within the operating profile of the process. The compaction cycle therefore encompasses any complete fluctuation of the packing factor and / or pressure indicative of a compression and relaxation sequence, regardless of whether such variation occurs continuously, periodically, or under controlled non-periodic conditions.

[0043] In particular embodiments, aspects of the present invention represent an advantage with respect to the technologies used in the art, as in particular configurations only a fraction of a surface being treated is processed during a compacting cycle. This capacity of treating fractions of surface provides the possibility of scanning a surface being treated, fraction by fraction in a customized compaction condition tailored to each requirement and geometry. For instance, an embodiment of present invention includes surface treatment through ion transport by means of electrically conductive solid particles retaining an electrolyte liquid, where a plurality of said solid bodies is being cyclically compacted when being rubbed against a fraction of the surface being treated and thereby scanning said surface fraction by fraction at each compacting cycle. In some cases, this cyclic compaction is applied by an additional element introduced for said purpose, in other cases the cyclic compaction is achieved through a combination of a surface of the part being treated in combination to other elements.

[0044] In some particular embodiments, only one of the four previous definitions is met (paragraphs defining the conditions of packing factor increase, pressure increase, current density increase, time period of a packing cycle and scanning conditions according to the present invention). In other particular embodiments, a combination of some or all the previous definitions is simultaneously met. In some cases, a fraction of a surface treated within each compacting cycle represents between a 0.1 % and 50% of the total surface, in particular between 1 % and 20%, more in particular between 5% and 10%.

[0045] Corresponding detection means or methods to detect the conditions previously described include pressure-sensitive films, piezoelectric or MEMS-based pressure sensors integrated in contact with the treated surface or embedded within the tool head to register localized compaction variations. Changes in the packing factor of the free solid particles may be detected by optical coherence tomography, laser triangulation, capacitive or inductive proximity sensors, or by acoustic / ultrasonic reflectometry to monitor variations in particle density within the electrolyte layer. Increases of current density can be measured through segmented electrodes, current shunts, Hall-effect current sensors, or distributed microelectrodes placed within or adjacent to the treatment area to provide spatially resolved current mapping. Additional modalities, such as thermal imaging cameras or infrared sensors, may also be used to indirectly infer local increases in compaction or current flow through detection of localized heating. These detection mechanisms may be used alone, combined or supplemented with data acquisition and signal processing systems capable of correlating temporal and spatial variations, thereby evidencing that at least within a fraction of the surface and during a limited period of time one or more of the specified conditions, e.g., pressure increase, packing factor increase, or current density increase, occur.

[0046] A compacting system according to the present invention refers to solid or liquid means that produces a change over a packing factor and / or pressure of a set of free solid electrolyte particles retaining an electrolyte liquid making them ionically conductive. In some cases, this means corresponds to a pressure wave applied to the free solid particles, in others to a fluid where the free solid particles are allocated or a combination of both (i.e. , pressure wave and fluid). Said means may include one or more of pumps, embolus, fleeces, turbines, aerodynamic elements in motion, sponges and more elements that will be further described.

[0047] In a particular embodiment of the invention, an increase or oscillations of the packing factor and / or pressure is achieved through the translation of a solid element within a set of particles. In some embodiments, translation is achieved by the motion of an element at constant velocity. In other embodiments, the translation speed is not constant and is changed between at least two speeds through a discontinuous or continuous acceleration. In some embodiments, the acceleration is performed in steps within all the polishing process. In some cases, the translation speed is changed continuously within all the process, such as in a sinusoidal curve or triangular curves. A motion and / or in particular an acceleration of a solid element attributed through generates an additional force transmitted to a set of particles in the form of a pressure wave. This pressure wave can be achieved by the acceleration of an additional translation element or by the translation of the part itself, wherein an increase on speed represents an increase of pressure and a decrease of speed represents a decrease of pressure.

[0048] In a particular embodiment, an acceleration attributed to a translation is accompanied by a rotation of the part being treated.

[0049] In some embodiments, a continuous linear acceleration includes a linear speed-time profile being selected from sinusoidal, triangular, rectangular, trapezoidal, sawtooth, sigmoidal, Gaussian, exponential, logarithmic, hyperbolic tangent, polynomial, spline-based, piecewise- linear, fractal-modulated, or combinations thereof.

[0050] In the present invention, in several particular embodiments where a non-conductive fluid is to be found on the environment of the solid bodies, the pressure is controlled by applying a recirculation of said fluid relative to the solid bodies and the surface to be polished. The venturi effect causes a change of the pressure between solid bodies and between the solid bodies and between the solid bodies and the surface to be treated by changing the relative velocity between them and the recirculating of non-conductive fluid. When a recirculation is configured in a way that the recirculation decreases the ratio between the effective non-conductive fluid and the solid bodies, it promotes the easier occupation by the particles at turbulent domains. In other cases, forcing the liquid to circulate against the direction of turbulence occupation, also creates the equivalent effect previously described for the recirculation in favor to the direction of turbulence occupation.

[0051] In particular embodiments, the increase of pressure and / or the packing factor of a set electrically conductive solid bodies is adjusted at a certain area of the surface being treated by a fluid recirculation drag force combined with a counter force applied to said set on the opposite direction. In some cases, an opposite force is applied by the surface being treated and in others by an additionally introduced element. In some cases, the introduced element is a mechanical element, such as a funnel, embolus, a fleece, etc. In some other cases, an opposite force is induced by a counter-recirculation of a fluid, in some cases the same fluid, in others another different fluid, i.e. , water against air.

[0052] In particular embodiments where a cyclic compaction period is applied solves several problems presented in previous systems known in the art including electrically conductive solid particles electrolytes that retain an electrolyte liquid. With respect to such systems known in the art, the disclosed aspects ensure an optimal electropolishing process results in grooves, undercuts, concavities or any complex geometry, enabling the possibility of obtaining high roughness reductions, including final Ra roughness’s below 1 pm or even below 100 nm without the presence of any corrosive effect.

[0053] A constant increase of pressure and / or increase of the packing factor of a set of solid electrolyte particles fractioned against a difficult-to-reach area of the surface being treated would allow for a sufficient electrical connectivity of a connected chain of solid bodies, triggering an ion transport between them and the surface being treated. However, if a release of that previously increased pressure and or increased packing factor is not applied, several corrosive marks can appear over the surface being treated as a result of an excessive electrochemical effect from a conductive solid body, in some cases, due to an excessive stationary contact relative to the surface being traded.

[0054] In order to achieve some required surface specifications (if any), the different parameters can be fine-tuned. Some of the relevant parameters that can be configured within the present invention include the current density, the period of a compacting cycle, the pressure and / or packing factor increase, the electrochemical time-pulses, duty cycles, chemical composition of the electrolyte, material being treated, sample size and geometry, relative motion and working temperature, among others.

[0055] Higher pressures and / or packing factor increase results on more aggressive processes, increasing the current density, resulting on faster surface treatments with higher roughness reduction speed. At the same time, a higher pressure and / or packing factor present higher susceptibility of leaving corrosion marks. In contrast, the lower the period of a compacting cycle, the lower the probability of leaving a corrosive defect. The selection of an optimal surface treatment according to the present invention relies on a compromise between the pressure and / or packing factor increase and the period of a compacting cycle.

[0056] The electrochemical aggressivity of the process will depend on the electrolyte’s chemical composition and its interaction with the material being treated, as well as the working conditions. One way to evaluate the aggressiveness of a process is its current density. Higher working voltages and the electrolyte’s conductivities will result on an increase of the current density. In particular embodiments, the period of a compacting cycle is tuned depending on the current density in order to obtain a certain level of roughness reduction, final achieved roughness and electrochemical defects. A process presenting a high current density sets an upper limit threshold of a compacting cycle period and pressure and / or packing factor increase, upon which greater values may leave corrosive marks.

[0057] The electrochemical time-pulses and duty cycles used for a particular surface treatment, as well as for the voltages, temperatures, relative motions, have an influence on the obtained final results. In some cases, these parameters are bound to the sample requirements and thereby the compacting cycle conditions used may be adapted according to those conditions. Higher duty cycles or lower anodic or cathodic time-pulses favor an electrical potential release between the electrically conductive solid body contacting the surface being treated, and thereby allowing for greater values of the compacting cycle period and pressure and / or packing factor increase. In contrast lower duty cycles or higher anodic or cathodic time-pulses will cause the opposite effect, require lower values of the compacting cycle period and pressure and / or packing factor increase to avoid corrosive marks.

[0058] In certain embodiments, a compacting element is included that operates, or is configured to operate, via a fluid recirculation mechanism through the solid bodies by means of another device (e.g., an external device), such as a recirculation circuit, which is not part of the medium in which the solid-particle based electrolyte is contained. In other embodiments, a compression mechanism is incorporated and physically positioned in direct contact with the solid bodies of the dry electrolyte.

[0059] In a particular embodiment of the present invention, compaction and decompaction of the solid bodies are applied periodically. In some embodiments, compaction and decompaction periods are applied cyclically over all the surface treatment. In some other embodiments, compaction and decompaction periods are applied within only one stage of the surface treatment.

[0060] A stage being defined as a part or fraction of a surface treatment.

[0061] One possible implementation of the invention, according to some embodiments, includes a meshed plunger or a plunger adapted to the geometry of the surface to be treated, wherein the plunger exhibits impermeable properties with respect to the solid particles and at least semipermeability to a portion of the fluid. In such an arrangement, when the plunger is pressed against the surface to be treated, the solid bodies are compacted against the surface, leaving at least a portion of the fluid behind.

[0062] Some embodiments incorporate sponges within the dry electrolyte. A mechanism may be configured such that, upon compression of the sponge, the release of the retained fluid results in a lower packing factor of the solid bodies. Upon decompression, the sponge reabsorbs the fluid, thereby increasing the packing factor as the fluid is reabsorbed. By adjusting the pore size and absorption properties of the sponge, different levels of compacting force can be achieved, making the system customizable. In one embodiment, the sponge is selective, exhibiting hydrophobic or lipophobic properties, which enables regulation or control of the fluid composition during compression cycles.

[0063] As a result of this innovative approach, new specifications for gears are developed, particularly concerning their surface finish. This advancement not only enhances the quality of the polished surfaces but also addresses the increasing demands for precision and performance in gear applications. By integrating cyclic compaction systems with dry suspension technology, this invention represents a substantial step forward in the field of surface finishing, offering a promising solution to optimize the polishing of complex geometries and improve overall material performance.

[0064] The compaction systems described in the present invention effectively compact dry suspension electrolytes to address the challenges posed by difficult-to-reach surfaces on different metal samples. The configuration of the compaction systems significantly enhances the interaction between the solid bodies and the surface being polished, leading to improved surface finish quality and overall performance.

[0065] Aspects of this invention inter alia include a method and an assembly for surface finishing various final products, including the smoothing and polishing of metal parts such as gears, concave surfaces, punches, and inner channels. In some particular embodiments, the process is based on ion transport facilitated by free solid bodies with the addition of a liquid as part of the dry electrolyte. The amount of liquid phase in the dry electrolyte, in some embodiments, can depend on one or more of: the tank used, the spaces that may exist in the conduits, the pump type, agitation mechanisms, electrolyte size particles, the receptable size and form, the sample to be polished, the applied pressure, liquid viscosity and the capacity of absorption of the particles. By basing the amount of liquid phase on one or more of the aforesaid magnitudes, the surface finishing (e.g., polishing) process may have the surface finishing result adjusted to greater or lower level of surface finishing, thereby allowing adjusting a speed of the surface finishing, one or more parameters representative of how the at least one surface treated has been surface finished, and / or the cost-effectivity of the surface finishing process.

[0066] The use of cyclic compaction systems in the electro-polishing industry can enable a wide range of significant applications, including achieving an optimal electrical field transmission and improving the surface treatment control in cavities, holes, or channels, and enhancing surface uniformity. This uniformity can be difficult to achieve in some materials, such as tungsten carbides. In some cases, depletions appear on their surface, which is detrimental for their performance and their life span and could be improved by adding vibratory systems to the compaction setup.

[0067] The distance to the cathode is a critical factor because it directly influences the efficiency and effectiveness of the polishing process. When the distance between the anode and the cathode is too large, the electrochemical resistance of the system increases, leading to a higher voltage requirement to achieve the same current density (too large being understood as for requiring excessive power to deliver so that the process becomes non-economically feasible). This can cause uneven polishing and reduced control over the surface finish. In some embodiments, a “too large” distance is 5,000 times or higher than the average size (e.g., the diameter) of a plurality of solid electrolyte particles.

[0068] Conversely, if the distance is too short so that there is a risk of excessive current density, which can cause localized heating, potential damage to the material, and non-uniform polishing. In some embodiments, a “too short” distance is 3 times or lower than the average size (e.g., the diameter) of a plurality of solid electrolyte particles.

[0069] Therefore, maintaining an optimal distance to the cathode ensures a balanced and controlled electrochemical reaction, leading to a uniform and high-quality surface finish. An optimal distance according to some embodiments is understood as a compromise between too short and too large adapted to the needs of the specific applications considering the relations previously disclosed about the distance. In some embodiments, an “optimal” distance is between 3 - 5,000 times the average size (e.g., the diameter) of a plurality of solid electrolyte particles, in particular between 5 and 500 times, more in particular, between 10 and 100 times.

[0070] As compaction increases, it is crucial to consider the operational parameters in the setup. This will result in a lower polishing voltage than previously used, especially concerning the positive voltage. The negative voltage does not need to be reduced, regardless of whether the materials are carbides, gears, or any other material.

[0071] The duration of action during compression is another vital parameter. Continuous contact during the polishing process can lead to overexposure, where certain areas of the material receive excessive polishing action. This overexposure can result in several issues as surface marks, excessive material removal or heat generation, which might alter the material's properties or cause thermal damage. To mitigate these risks, controlling the compression time is preferred. Intermittent contact or precisely timed polishing cycles can help achieve the desired surface finish without overexposing the material. It is advantageous to synchronize the compression and decompression times of the electrolyte with the polishing parameters, establishing a correlation between positive pulses, negative pulses, and pauses. Said compression cycle and polishing parameters have a period raging between 1 ps and 10 s, in particular between 5 ps and 2 s, more in particular between 10 ps and 1 s. Additionally, monitoring the process and adjusting parameters may ensure that the material is polished evenly and efficiently.

[0072] In several particular embodiments, mechanical elements are included (e.g., in the system, in the method, etc.), as part of the dry electrolyte, such as abrasive materials, generating a hybrid mechano-galvanic surface treatment.

[0073] In other embodiments of the invention, mechanical elements are included (e.g., in the system, in the method, etc.), as part of the dry electrolyte, without presenting an abrasive function, such as glass spheres. These elements can serve as edge protection. They can act as buffers, reducing the direct impact and preventing excessive rounding or damage to the edges. However, there are also challenges associated with adding mechanical elements as there could be uneven polishing. While these mechanical elements (e.g., PVC polymeric non-conductive particles) can protect edges, they can also create zones where the polishing process is less effective. For this reason, it is important to use the proper proportions, particle size distributions and apply a finetuned pressure and force distribution to ensure that areas with mechanical elements do not receive less polishing action, or the incorporation of monitoring and feedback systems that track the areas where unevenness is occurring. Proper proportions may be selected to ensure there is sufficient amount of solid electrolyte particles to conduct a galvanic surface treatment through said solid electrolyte particles while achieving the desired effect of the included mechanical element (e.g., edge protection). In some embodiments, a proper proportion of the solid electrolyte particles to mechanical elements range between 100:1 and 1 :2 in volume more in particular between 10:1 and 1 :1 , particularly between 5:1 and 2:1.

[0074] The nature of cyclic compaction systems makes them suitable for polishing the inner surfaces of various components, such as hydraulic cylinders, valves, intricate brackets, bearing gears, heat exchangers, manifolds, and other parts characterized by complex geometries.

[0075] The processes, systems, assemblies and parts that fall within the scope of the present invention include surface treated conductive materials, such as ceramic, metallic or composites, such as MMCs.

[0076] The materials that can be treated using cyclic compaction systems include cast iron, steel, tool steel, stainless steel, titanium alloys, aluminum alloys, nickel alloys, cobalt-chromium alloys, hard metal alloys, copper alloys, brass, Zamak, semiconductors, gold, silver, and platinum, among others. The cyclic compression systems encompass various embodiments that enable precise control over the resin compaction at specific points where the desired polishing area is located. In some embodiments, such control is achieved by focusing a cyclic compaction mechanism to a specific area of the receptacle holding the solid particle-based electrolyte and thereby compacting a subset of solid electrolyte particles against a local fraction of the surface being treated. This functionality allows for the controlled movement of the polishing medium precisely where it is needed most, enhancing the overall efficiency of the polishing process.

[0077] A particular embodiment comprises pressure regulation through pump flow rate. By modifying the flow rate, it is possible to fine-tune the current delivered to the system, thereby optimizing the polishing action based on the specific requirements of the material and the desired finish.

[0078] Furthermore, the configuration of compression systems in accordance with some embodiments can be tailored to suit a particular geometry of the part being processed. This adaptability is a significant advancement over previous technologies, which often struggled to effectively polish complex shapes. By enabling precise control over the compression parameters, these systems can achieve uniform polishing results on intricate surfaces that were previously difficult or impossible to refine.

[0079] When polishing surfaces with this type of compressive systems the liquid component is ejected from the polishing zone leaving behind a bed of particles that helps them to reach all surfaces of interest.

[0080] Crushed resin particles tend to cause filtration problems because they can easily clog the system, which hampers efficient operation. In several particular embodiments, to mitigate this, it is crucial to adjust the liquid-to-particle ratio. Increasing the liquid content can help in maintaining an optimal flow and preventing blockages that might arise from the accumulation of resin particles.

[0081] Moreover, the concentration of particles within the medium should preferably be controlled. A high density of particles can result in interstitial air being trapped between them, which can compromise the efficiency of the system, particularly affecting the performance of the pump. Trapped air can cause cavitation, reduce the pump’s effectiveness, and lead to mechanical failures over time.

[0082] These cyclic compression systems enhance the durability of the electrolyte by increasing the liquid-to-solid ratio within the polishing medium. This higher ratio allows for more effective distribution of the liquid component, reducing wear and tear on the solid particles and extending the overall lifespan of the electrolyte. Furthermore, the liquid can also contain ionic particles of the metal being polished. Additionally, the design of these systems facilitates easy renovation of the liquid component, enabling straightforward replenishment or replacement as needed. This not only maintains optimal performance but also reduces the frequency of complete electrolyte changes, further contributing to the system's efficiency and cost-effectiveness. This system is designed to polish conductive materials, particularly a wide range of metal alloys. The system enables effective polishing of materials comprising aluminum, stainless steel, steel, titanium, chrome-cobalt, nickel, and high-speed steel alloys. Additionally, the system is suitable for polishing brass, carbide alloys, copper alloys, bronze, zinc, Inconel and tungsten- based alloys.

[0083] In several particular embodiments, the dry electrolyte comprise free electrically conductive solid bodies with affinity for retaining a liquid electrolyte, which enables them to present electrical conductivity. More specifically, this solid bodies can include ion-exchange resins, particularly cationic resins, such as polystyrene divinylbenzene sulfonic resins. The particles utilized in the system may be either macroporous or gel-type, depending on the specific application requirements. In a particular embodiment of the invention, the solid bodies include a chelating resin. The present invention includes different geometries and sizes for the solid bodies. In a particular embodiment, the solid bodies are spherical, with a diameter between 10 pm and 10 cm, in particular, between 200 pm and 1 cm, and more in particular between 300 pm and 1 ,5 mm. In particular embodiments of the invention, the particles range in size from 10 micrometers to 2000 micrometers, more specifically between 40 and 1500 micrometers, and even more specifically between 80 and 1250. Other shapes can be included or used on the present invention, such as cylindrical, pyramidal and squared. In certain configurations, different combinations of shapes and sizes can be used.

[0084] The resin used in the system can be impregnated with a solution to enhance its conductivity, allowing for improved polishing performance. This can be achieved by utilizing various acids, such as sulfuric acid, methanesulfonic acid (MSA), nitric acid, and phosphoric acid, which effectively increase the ion exchange capability of the resin. Other useful acids include hydrochloric acid, citric acid, and oxalic acid, all of which contribute to enhancing the conductive properties of the resin.

[0085] Interstitial gaps between the free solid particles in the system can include non-conductive fluids, which may include hydrocarbons such as mineral oils, paraffins, or silicone oils, more specifically, a mixture of aliphatic hydrocarbons with a carbon chain between 12-15 C containing less than 2% of aromatic groups. Other non-conductive fluids, such as certain synthetic oils and inert gases, can also be utilized depending on the application. Additionally, in some embodiments, various elements are incorporated into the electrolyte to further enhance its functionality. These may include surfactants to reduce surface tension, abrasive particles to aid in material removal during polishing, or moderator particles to control the polishing rate and prevent excessive wear or damage to the material being treated. In some particular embodiments, other possible components that are included on the interstitial space between solid bodies are fatty acids, glycols, sulfoxides, ionic liquids, deep eutectic solvents, phenols and fatty alcohols. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] To enhance the understanding of the disclosure, a series of drawings are included. These drawings are an essential part of the description and depict various embodiments of the disclosure. They are not intended to limit the scope of the disclosure but rather serve as examples of its implementation. The figures included are as follows:

[0087] Figure 1 - Illustrative example of a cyclic compaction system with a densified bed of resin particles using a single piece for polishing, in accordance with some embodiments.

[0088] Figure 2 - Illustrates a cyclic compaction system wherein the movement of the component exhibits periodic oscillation with an amplitude of the order or greater than the dimensions of the part or the surface to be surface finished, including vertical and horizontal movements, in accordance with some embodiments.

[0089] Figure 3 - Illustration of a cyclic compaction system with a rotating densified particle bed for gears or revolution-shaped parts, in accordance with some embodiments.

[0090] Figure 4 - Illustration of an inverted cyclic compaction system with a densified particle bed over a movable cathode appropriately shaped for the piece, in accordance with some embodiments.

[0091] Figure 5 - Characteristics of the different parts of gear teeth.

[0092] Figure 6 - Illustration of a cyclic compaction system including an injection and removal of a fluid substance, in accordance with some embodiments.

[0093] Figure 7A - Illustration of a 3D assembly according to some embodiments of the present invention

[0094] Figure 7B - Longitudinal cut of Fig 7A

[0095] Figure 7C - Lateral view of an assembly according to figures 7A and 7B in working conditions.

[0096] DETAILED DESCRIPTION OF THE DRAWINGS

[0097] This section will provide detailed explanations of the illustrations depicting various cyclic compression systems. For simplicity, electrical connections and power sources have not been illustrated as for any example, the following conditions are met.

[0098] A system or assembly configured to surface treat a metal part, comprising: a system adapted with means for connecting an anode to a positive pole of an electrical power supply and connecting a cathode to a negative pole of said electrical power supply; a fixing system adapted to an electric connector to hold a metal part as one of the two electrodes; means for generating a relative movement between a surface to be treated with respect to a dry electrolyte; said dry electrolyte including free electrically conductive solid bodies; and a compression system, according to the present invention, to compact said solid bodies.

[0099] In several particular embodiments, the system includes adjustable parameters for the cyclic compaction process, including but not limited to the thickness of the compacted particle layer, suction force, vibration frequency of the setup, voltage, electrical pulse timing, and electrolyte composition; configurable components or attachments that can be tailored to specific industrial applications, different part sizes, or particular surface finishing requirements; system further including user-adjustable settings or interfaces that allow operators to modify and optimize the compaction parameters based on the unique needs of each polishing operation.

[0100] In several particular embodiments, the system incorporates a protective chamber designed to isolate portions of the sample that are not to be polished when submerged in the electrolyte, where a protective chamber can be of cylindrical or other geometric shapes and a chamber can be pressurized to prevent liquid from entering and ensure that only the designated portion of the sample is polished; a chamber can be filled with air or any other material that prevents electrical or chemical interaction, creating a barrier to protect the non-polished areas; a chamber preferably further comprising adjustable features, such as seals, flexible membranes, or variable pressure systems to accommodate different operational needs and ensure effective isolation, and an adaptation of the chamber to use a combination of pressurization, air-filling methods, or other configurations.

[0101] The following illustrations can be found in the drawings section, where each system is carefully represented to enhance understanding of their functionalities and applications.

[0102] In a particular embodiment of a compression system, such as the represented on Figure 1 , that comprises motion-generating components (100-106), a polishing receptacle (110-118), and a liquid refill system (120-124).

[0103] Some motion-generating components (100-106) provide both vertical movements along one axis and a slight movement within the perpendicular plane, which imparts a circular motion to the piece. The configuration of a motion system can be realized in various ways; the arrangement depicted in Figure 1 represents one possible assembly although it can be done in different ways. The system comprises two motors (101 , 105) that deliver movement across the different axes. A horizontal motion system consists of a rotational system, such as a pulley (100), which is connected to a gear belt (102) for motion transfer. Meanwhile, a vertical movement is guided by a transmission device, as it can be a gear crank (104) that is linked to various components acting as anode connection (103) creating a high frequency cyclic compaction (106).

[0104] When implementing movement along the horizontal and vertical axes with a motor (101), an objective is to prevent the particles from lacking the sufficient relative movement with respect to the surface to be treated, for achieving a successful result in terms of homogeneity, particularly in hard-to-reach areas. However, a part to be polished features intricate details with variations between the order of the size of the particles and hundredths of the size of the particles, and thus excessive movement amplitude could be counterproductive. This excessive movement may create zones with limited electrochemical action of the resin particles due to the wake effects generated by a high amplitude motion. For the reasons exposed before, a relation between a size of details with respect to a configured amplitude is preferably between 0,1 to 100, more preferably from 0,5 to 10, in particular between 1 and 5.

[0105] When implementing movement along the horizontal and vertical axes using a motor (101), in a particular embodiment, the particles maintain sufficient relative motion with respect to the surface being treated, facilitating uniform polishing, especially in hard-to-reach areas. However, excessive movement amplitude can be counterproductive, particularly when the particle size exceeds the geometric details of the piece. In such cases, large amplitudes can create zones where the particles cannot effectively reach the surface, reducing electrochemical action.

[0106] A polishing receptacle (110 - 118) comprises various components, among them, e.g., a part to be polished (112), namely an anode and which may or may not be part of the system, and an electrolyte. The electrolyte is composed of resin particles (110) and a free liquid component (111). Upon closer examination of a system where free solid particles are compacted, a high- density layer (113) of these particles can be observed, which is caused by a liquid absorption from a pressure generation system, such as a pump (123). Beneath a layer of particles lies a cathode (114), followed by a particle filter (115) and a support structure (116) to prevent the filter (115) from bending. When a liquid is absorbed, it passes into a chamber (117) located at the bottom of a receptacle (118) for subsequent recirculation.

[0107] A liquid recirculation system (120 - 124) can be implemented in various ways, and Figure 1 exemplifies one of them. This system collects a liquid after it passes through a cathode (114) and a filter (115) attached to a filter support (116), redirecting it to the upper part of a polishing receptacle. In a particular embodiment, the liquid travels through collapse-resistant tubing, as an anti-collapsible hose (120) to a liquid outlet conduct (121). Additionally, this recirculation system may include an automatic liquid level regulator (122), which allows a liquid to flow through the lower part of a polishing chamber by gravity when a pressure generating system is stationary, thereby decompressing a layer of free solid particles. Furthermore, this system may incorporate a pressure regulating valve to adjust a suction force of a pump (123). Furthermore, this system can be equipped with a pressure control mechanism (124) to regulate the compaction of particles.

[0108] In several particular embodiments, during a refill process, no bubbles are formed. The presence of bubbles can disrupt the functionality of a cyclic compaction system, leading to inefficiencies and potential malfunctions. To prevent this issue, a system with means for providing a liquid (111) to flow down the walls during the refilling is configured. This method ensures a smooth and steady introduction of a liquid (111), minimizing turbulence and avoiding an entrapment of air.

[0109] A cyclical compression system as defined on Figure 2 bears similarities to the one described in Figure 1 , as it also relies on a repeated immersion of a workpiece in an electrolyte. However, the distinction lies in the configuration of the electrolyte (211 and 212) container and the relative motion between an electrolyte (211 and 212) and a workpiece (213).

[0110] In several particular embodiments, preventing consecutive impacts on the same area to the same electrolyte surface is preferred. A purely vertical movement would cause the workpiece to continuously strike the same spot, potentially deforming the electrolyte in a way that alters its contact with the workpiece during subsequent impacts, negatively affecting the polishing process. Additionally, an initial impact creates a cavity in an electrolyte that may later become filled with liquid. Therefore, if a workpiece (213) is later placed back into the same position, proper contact may not be achieved, resulting in only liquid remaining between a workpiece and an electrolyte, which can lead to non-uniform polishing. To address this issue, several strategies can be implemented to ensure proper contact between the workpiece (213) and the electrolyte. One approach is to introduce movement that ensures a change in the position of each impact. This movement can be rotational, where the workpiece is rotated to engage different areas of the electrolyte surface, or translational, shifting the workpiece laterally. Alternatively, the container holding the electrolyte can itself be moved to expose fresh areas of the electrolyte, thereby preventing repeated strikes on the same spot and ensuring more uniform contact.

[0111] Another alternative to address this issue is by introducing a controlled amount of liquid from a closed recirculating system after each impact, re-homogenizing the electrolyte. This recirculated liquid is drawn from tubes that previously extracted the liquid portion during earlier stages, contributing to the compression process. By reintroducing this liquid, the electrolyte returns to a uniform state, preventing cavities or deformations caused by repeated impacts.

[0112] In this system, a rectangular receptacle can be utilized, with the workpiece being displaced to a new position along an axis each time it is lifted. Movement is achieved either by relocating a workpiece or by moving a receptacle. This design ensures complete renewal of resin particles during each compaction cycle.

[0113] In a particular embodiment of the invention, the movement experienced by a workpiece is longitudinal. When a workpiece reaches an end of its path, automatically or manually a suction pump halts, and a workpiece (213) is repositioned to a starting point. To enhance efficiency, a system which the workpiece is processed continuously can be developed. In a particular embodiment, a container presents a circular shape, allowing a workpiece to move radially over it. Thus, while a workpiece is lifted from an electrolyte and repositioned for a next immersion, liquid part of an electrolyte is injected at several bottom positions of a tub. This approach ensures a continuous renewal of particles in a polishing zone. Moreover, an implementation of an electrovalve enables controlling the liquid injections in the moment of workpiece (213) removal. This advancement leads to an automated process, yielding improved results.

[0114] Regarding the illustration from Fig. 2, its components are similar to those from Fig. 1.

[0115] In this sense, Fig. 2 describes one of the possible configurations, in accordance with some embodiments, for generating a relative movement between the workpiece (213) and the particles (212), based on high amplitudes, as described before. In a particular embodiment, means for providing horizontal movement includes a motor (200), which powers a threaded rod (201) that moves an entire movement platform (202) from side to side through linear rails (203). Additionally, a motor (204) that rotates a gear crank (205) is included to generate a cyclical compaction movement. A vertical axis guide (206) is included to limit movement in that direction. Finally, to create some motion along the perpendicular plane, there is a pulley (207) with a gear belt (208), which may produce a movement more akin to that of a crankshaft than that of a piston, powered by a motor (209).

[0116] In several particular embodiments, a polishing system comprises a container referred to as a receptacle (210). This receptacle contains, at its upper part, an electrolyte composed of ion- free liquid (211) and free solid electrolyte particles (212) and a workpiece (213), connected to a mobile arm via a component referred to as an anode connection (214). Said workpiece is submerged at various points comprising the mentioned electrolyte (211 and 212). Due to a suction of a liquid, a more compact layer of particles (215) forms at the bottom, in contact with a cathode (216), beneath which is located a filter (217) for resin, and below that, an anti-collapsible support

[0117] (218). An absorbed liquid passes into a lower liquid chamber (219), which is then recirculated.

[0118] The packing factor of particles connecting the cathode (216) and the workpiece (213) during a polishing process should be preferably configured, in particular configured so as to not be excessive but rather optimal for effective polishing of a workpiece, considering that higher PF delivers better surface treatment penetration over concavities and that lower PF provides with lower final roughness. An excessive width of the particles compact layer (212) (i.e. , with a length of more than 500 times the average diameter of a set of particles), can create gradients in inner regions, leading to heterogeneous surfaces after polishing. As the layer thickness increases, precision in a polishing process is compromised, negatively impacting a result. Additionally, it is possible to include a longitudinal movement of the workpiece involving an up-and-down motion that facilitates electrical contact and then halts. This motion allows achieving consistent electrochemical action, ensuring that a polishing process is uniform and effective across an entire surface of a workpiece.

[0119] In particular embodiments, electrolyte recirculation systems comprise a pressure generation system, such as a pump (220) that absorbs a liquid from an electrolyte, thereby compacting and forming a layer of compacted particles. A liquid is expelled from a liquid chamber

[0120] (219) through a fluid inlet (221) and is reintroduced into an electrolyte placed on a receptacle via the fluid outlet (222), where an anti-air bubbles liquid diffuser (223) is located. This system also comprises a self-regulating liquid system (224), which operates, in this particular case, through compressive and gravitational forces. Finally, a pressure regulator or controller (225) can be installed, allowing for any adjustment of the suction pressure of a pump, thereby increasing or decreasing a compaction effect of particles. It is also important that a liquid is reintroduced into the cyclical compression systems without generating any turbulence, as this would produce bubbles in an electrolyte that, if absorbed by a pump, could hinder its operation. For this reason, a liquid to flow along a wall is preferable. This effect is created with an anti-air bubbles liquid diffuser (223). In some other embodiments, more liquid is added in the system, and allowing a valve to be placed directly within it. The latter may result in an increase in pressure within a cylinder, potentially raising a remaining amount in a self-regulating liquid system (224), with a smaller diameter. Consequently, this could lead to an increase in pressure until it equals that of a level at which this conduit begins.

[0121] A cyclical compaction system as shown in Figure 3 differs somewhat from the two previous systems; however, it is based on the same principles of resin compaction. This system is particularly convenient for the polishing of gears and / or other revolution-shaped components.

[0122] A particular embodiment of the present system is based on a rotatory wheel (300) that features a cathode (301) on its outer surface and a filter (302) beneath it. Behind a filter there is a support structure (303) to prevent a filter mesh from bending. This support structure includes holes on its surface to allow an expelled liquid to pass through and is designed to be robust, serving as a break-resistant support. A liquid is drawn through this surface while it rotates.

[0123] At both ends of a revolution-shaped object, such as a cylinder, there are two crown-shaped structures (304), these perpendicular walls to a radial cathode are designed to retain particles (307) in an area between an anode / workpiece (305) and a cathode (301). The diameter of a circular crown is determined by the size of a gear tooth. As the size increases, a layer of resin particles formed will be thicker to cover the entire surface of a tooth, and therefore, these walls would also require a larger outer diameter.

[0124] Further, there is a workpiece (305) to be polished; in this case, it is represented as a gear that rotates in an alternating direction. Each time a gear completes a rotation, a small degree of compaction occurs, which is enhanced by a densified bed of particles on a wheel.

[0125] As a system comprising the cathode rotates, particles position themselves around the cathode and acquire a certain concentric movement. These particles, positioned between a gear and a rotating system, form a compressed bed of free solid bodies (306) which is essential for achieving a high-quality surface finish on a gear. In several particular embodiments, particles are continuously renewed, as they fall due to gravity when are further from an axis of rotation, while a rotation itself draws new particles from a lower region of a tub.

[0126] However, the quantity of free solid particles that can be present in the receptacle is limited (307); if more particles are added, a rotatory wheel (300) may become obstructed due to a friction generated by a suction around its perimeter.

[0127] A liquid recirculation zone, in some cases begins with collapse resistant tubing, such as an anti-collapsible hose (310), which collects the liquid drawn through a cathode system, filter, and support using the force of the pump (311). This liquid then passes through a self-regulating liquid level system (312) and re-enters a system through an anti-air bubble liquid diffuser (313). This ensures that a liquid is evenly distributed without introducing air bubbles, thus maintaining optimal operating conditions within a system. There is also a possibility of incorporating a pressure regulator (314) in the system for affecting this compact layer of resin particles and, consequently, the polishing of a workpiece.

[0128] The movement system of this cyclical compaction system is based on two rotating axes: one that drives a cathode (301) and another that rotates the workpiece (305) to be polished. Motors and gears must be adjustable through at least one adjustable axis (315) to accommodate different diameters of workpieces or varying sizes of gear teeth. It is important to control the liquid level, as if it is low enough for a wheel, along with the thickness of compacted particles, to protrude above a surface, air will enter to the system through interstitial spaces between particles.

[0129] In this configuration, axes rotate through sliding contacts (316 and 317) that are connected to their respective motors (318 and 319). This design allows for efficient transmission of motion while ensuring that both a cathode and a workpiece can operate simultaneously and independently.

[0130] While this specific configuration is effective, it is important to note that alternative arrangements for motion transmission could also be implemented. The flexibility of a system allows for customization based on the specific requirements of a surface treatment, ensuring optimal performance across various applications.

[0131] In Figure 4, an inverted compaction system is illustrated, where a workpiece to be polished is submerged in a liquid environment, and a cathode retaining electrically active particles performs a compaction movement on a workpiece. This system can be used for polishing punches, although it can also polish various types of components and materials, such as dies, mandrels, brushings, molds, bearing seats, drills, among others. In some embodiments, materials suitable for being surface treated according to Figure 4 include, steel alloys, stainless steel alloys, metal matrix composites, tungsten carbide, cast iron alloys, among others.

[0132] The fact that the movement relies on a cathode offers several advantages, such as the ability to polish large parts without the need to move a workpiece. This is particularly beneficial, as moving heavy or complex geometries could present mechanical complications. Consequently, various electrolyte delivering mechanisms, such as injectors, which dispense an electrolytic media, that can include resin and liquid part, can be positioned along with one or multiple cylinders to facilitate a compaction movement of resin, ensuring a more efficient polishing process.

[0133] A particular embodiment of the invention comprises a workpiece (400) placed inside a cylindric chamber (401) filled with a gas, such as air, that comprise on the top a perimeter protector (402) to prevent the liquid, such as water, from entering around the edges of the component. Gas, such as air, is blown in from the bottom of the tube through a gas inlet (403) by a gas pump (404) to ensure that if any liquid enters, it is kept out of an enclosed space, as it is challenging to make the enclosure completely airtight with seals, but it would be the desired outcome. The use of compressed gas can help to further enhance protection of a workpiece by creating a barrier against unwanted substances. This configuration is particularly beneficial for protecting parts of a workpiece that is susceptible to corrosion.

[0134] The liquid is drawn through a cathode (405), mesh (406), and a break-resistant support (407) by a pressure generation system, such as a pump (408), that provides a suction force to absorb the liquid. The shape of the cathode can be modified or designed to best suit the geometry of a workpiece. For instance, if it is necessary to reach a concave surface without current gradients, employing a cathode that matches a specific contour will facilitate a more uniform polishing across an entire surface.

[0135] The liquid flows through flexible tubing, such as an anti-collapsible hose (409). It can be directed towards two outlets: the first pressure generation system outlet, which will be called the first pump outlet (410) and the second pump outlet (411). The first outlet is connected to a conduit (412), which features a particle inlet (413) located at the bottom. This conduit collects free solid particles (414) that are submerged or near the inlet, which enter through it due to a flow inducted pressure change, as the venturi effect (415). These particles, along with the liquid, continue through the conduit until they reach the end, located midway between a workpiece (400) — such as a punch — and a cathode (405).

[0136] Particles are compacted against a workpiece by a cathode itself, as it is a component that is in motion. In a space between a workpiece and a cathode, there are particle retention walls (416) that assist in forming the compacted resin layer (417).

[0137] In particular embodiments, if a workpiece is larger or exhibits an uneven surface, such as cavities or undulations, there may be particles that remain on said polishing surface, which could result on defects during a subsequent compaction. This issue can be resolved by introducing delivering mechanisms, such as injectors, that direct fluid towards the surface to be polished, effectively cleaning it and ensuring a smoother finish.

[0138] A second pressure generation system outlet, in several particular embodiments, comprises a second pump outlet (410) configured to expel an exhaled liquid and assists in controlling the quantity that passes through a first outlet with a pressure regulator (418). This allows for the enhancement or reduction of the Venturi effect. To determine a desired thickness of the densified bed, it is sufficient to regulate a pressure of the second pressure generation outlet; thus, thickness can be increased or decreased as needed.

[0139] In this model of the cyclic compression system, movement of a cathode (405) is generated by a motor (419), which drives a gear crank (420) that is directly connected to an arm attached to a cathode. This movement in a particular embodiment, is produced by a crankshaft mechanism.

[0140] The different cyclic compression systems previously presented include a liquid recirculation system powered by a pressure generation system, such as a pump, which is responsible for compacting particles onto a filter. A pump can be utilized in different modes. Keeping it continuously on, which presents a risk of clogging the separation device, like a filter, that may lead to a total or partial loss of suction force at a densified bed. Another option can be activating the pump cyclically, that would result in a reduced risk of obstruction, allowing for a renewal of the particles and partial cleaning of a filter. Another option present in some embodiments is a configuration to alternate the direction of a pump cyclically, as this minimizes the risk of filter obstruction while facilitating complete renewal and cleaning. This pause in suction or inversion of fluid flow would occur while a workpiece and the cathode are being separated.

[0141] Some systems, however, rely on a tubing system-controlled through pressure and gravity forces that injects liquid from below to expand particles forming the solid electrolyte layer when a pump is off, eliminating a need for additional changes.

[0142] The frequency of cyclic compaction is determined by the capacity and / or suction limits of a pressure generation system. However, a higher frequency can yield better results, in terms of treatment speed and final roughness, provided that a system can expel the liquid phase from the enclosed areas at a sufficient speed. Increased frequency enhances the mobility of the particles, allowing for more efficient compaction and improved overall performance.

[0143] In the described configuration, cathodes can design in a grid-like structure; however, they could be configured in various other shapes to suit specific requirements. Additionally, the mesh used as a filter is screen-printed mesh, with the design tailored to accommodate the dimensions of the particles contained in the electrolyte being used.

[0144] In certain embodiments of the invention, a control mechanism for the current flow synchronized with the critical moment of compaction is beneficial. This synchronization is particularly important during the final centimeters or millimeters of the movement of a workpiece or a cathode system. By controlling or managing the current at this stage, one can enhance an electrochemical process involved, ensuring optimal particle compression and a more uniform surface finish.

[0145] In order to avoid interstitial spaces by exerting a force that expels particles, which undermines the desired compaction process, on the movement generation system, an effective motion to apply, sometimes the most effective motion, resembles that of a rotational drive system, such as a crankshaft mechanism, as it promotes a more uniform distribution of force and minimizes the risk of particle displacement, resulting in improved compaction efficiency and overall performance.

[0146] In several particular embodiments, the flow rate of a liquid coming from a pressure generation system, such as a pump, can be adjusted to create a thicker or thinner layer of compacted particles, depending on the specific requirements of a workpiece. The maximum negative pressure that can be expected at a densified bed, without utilizing a pressurized chamber, is 1 atm. Figure 5 depicts the characteristic surfaces of a gear, enhanced in quality by embodiments of the current invention.

[0147] By adapting a compaction system, including factors such as the thickness of the compacted particle layer, suction force of a pump, rotational frequency of both cathode and gear shafts, electrolyte composition, and polishing time, it is possible to achieve better results, presenting lower final roughness values. This optimization leads to gears with improved performance and efficiency.

[0148] When considering surface roughness, different techniques yield varying results for each part of the gear. For instance, with the cyclic compression system illustrated in Figure 1 , where the raw part of a gear exhibited the following roughness values: 0.36 pm for the face (500), 0.57 pm for the crest (501), 0.33 pm for the flank (502), and 0.80 pm for the valley (503), a polishing duration of, e.g., twenty minutes can result in significantly lower roughness values, achieving 0.25 pm for the face (500), 0.39 pm for the crest (501), 0.15 pm for the flank (502), and 0.52 pm for the valley (503).

[0149] The present disclosure also refers to a gear final product, or similar. In a particular embodiment, the gear comprises a roughness value Ra below 1 pm, in particular a roughness value over all its surfaces between 0,8 and 0.1 pm. More in particular a roughness value over all its surfaces between 0,3 and 0.1 pm.

[0150] A particular embodiment, when said gear is case hardened, comprises a gear comprising the previously described roughness specification keeping a geometric tolerance below 1 pm after the polishing process. More in particular, a gear comprising the characteristics mentioned before while keeping a surface HV value between 80 % and 99% of the roughness obtained after its surface finish.

[0151] In the case of a cementing process, where carbon is diffused into the surface layer of the steel at high temperatures (around 850-950°C), the carbon-rich layer is then quenched, leading to a very hard, martensitic surface while maintaining a tough core. The surface hardness of a carburized gear can typically achieve values in the range of 650-900 HV. The present invention includes gear component comprising an improved surface treated surface, including at least a case-hardened surface by a cementing treatment keeping a surface hardness value between 600 - 900 HV.

[0152] In the case of a nitriding or nitrocarburizing process, where nitrogen (and sometimes carbon, in nitrocarburizing) is introduced into the surface at relatively lower temperatures (around 500-580°C), generating a hard, wear-resistant surface by forming nitrides with alloying elements like chromium, aluminum, or vanadium in the steel. The surface hardness of a carburized gear can typically achieve values in the range of 900 - 1200 HV. The present invention includes gear components comprising an improved surface treated surface, including at least a case-hardened surface by a nitriding or nitrocarburizing treatment keeping a surface hardness value between 800 - 1200 HV.

[0153] A cyclic compaction system represented in Figure 6 consists of the compaction and decompaction of resin-free solid particles through the injection and removal of a fluid substance such as a gas into a moldable container, such as a durable bag.

[0154] The operating principle of this system is based on the displacement of the liquid phase of an electrolyte by increasing or decreasing the volume of a moldable container. When the volume of this container increases, the liquid phase of the electrolyte is displaced through the particles and increasing an interstitial space between them. Conversely, when the volume of the moldable container decreases, the liquid phase is displaced into this freed volume, compacting the resin- free solid particles on the upper part of a filter. Such a compaction system allows for increased conductivity during the compaction process and improves conformity to the geometry of the piece being polished, resulting in a better finish with less roughness and greater shine.

[0155] The compaction system is composed of a structure that allows for the placement of a moldable container (603) between the lower part of the structure and an upper surface that limits the passage of resin particles. This structure, in a particular embodiment, includes two receptacles: the lower receptacle (601) and the upper receptacle (602), which has a filter (610) at its bottom that allows the liquid to pass up to a certain level (606). When the volume of the moldable container (603) is increased through an inlet (604) which can be connected to an actuator device, such as a piston, that pumps any sort of volume, such as gas, the liquid is displaced to this level (606), uncompacting the resin-free solid particles (605).

[0156] Conversely, when the volume of the moldable container (609) is reduced, the space it previously occupied is filled by the system's liquid, which leaves the upper part with a smaller amount of liquid (608) and compacts the resin-free particles (607).

[0157] Figure 6 shows two sets of assemblies or system: the two upper ones, which represent only the container-particle assembly, and the two lower ones, where the same container-particle assembly is depicted but with the electrodes included. The cathode, in this case, has a spherical shape and includes a lower section. The cathode can adopt other configurations, such as only including its lower section, positioned above the filter (610). Figure 6 also shows the piece to be polished, which in this case acts as the anode (612), although both electrodes can switch roles. The piece can perform various movements, both vertical and rotational, or a combination of both.

[0158] The increase or decrease in the volume of the inner chamber can be synchronized with the polishing parameters or the movement of the piece to achieve better polishing results.

[0159] A component with improved performance underwork conditions comprising a gear with at least one of the characteristics previously mentioned is within the scope of the present invention. Said improved performance may be implemented in various applications, such as automotive transmissions, aerospace gear systems, industrial robotics, wind turbine gearboxes, medical equipment, racing engines, and high-speed printing presses. These gears benefit from reduced friction, leading to lower heat generation, increased efficiency, and improved durability. The smoother surfaces also reduce wear, vibration, and noise while enhancing load distribution and fatigue resistance, resulting in longer lifespan and better performance in demanding, high- precision, or high-stress environments.

[0160] Another embodiment of the invention represented on Figures 7A to 7C, includes surface treatment wherein a cyclic compacting system is configured to generate a pressure wave through the translation of a pressure wave device within a set of solid electrolyte particles.

[0161] Particular embodiments of the invention represented on Figure 7A, 7B and 7C include a device comprising: a receptacle (704) configured to receive a solid-particle based electrolyte (706); an object being surface treated (708) at least partially arranged inside the receptacle (704) by the help of a fixing system (709); a cyclic compacting system (705, 703, 702, 701) comprising an pressure wave device (701) adapted with means for being cyclically moved (703, 702) through said solid particle-based electrolyte (706), where the motion of said pressure wave device (701) is configured to generate a compacted solid particles pressure wave (707) that transitorily connects a fraction of a surface of the part being treated (708) and the pressure wave device (701); a power supply providing a potential difference between a conductive element, that in some cases is part of the pressure wave device (701) or the receptacle (704), and the part being treated (708) and thereby enabling their ion exchange trough the connected solid particles pressure wave (707).

[0162] A pressure wave device (701) according to the present invention is to be understood as a solid object capable of inducing a pressure wave (707) towards a surface of the part being treated (708).

[0163] A configuration of the present invention presenting a surface treatment based on a scanning of fractions of a surface being treated, offers several benefits. In particular for delivering a surface treatment of big parts, such as stamping or injection molts. Electrochemical polishing of big parts represents a challenge for delivering the sufficient power to achieve current density to obtain a successful surface treatment. In addition, the different geometries presented by the surface of such big components make it difficult to provide with a uniform finishing using conventional solid-particle based electrolytes polishing systems. By a generation of a compacted wave of electrically connected solid particles (707) in contact with a fraction of a surface being treated, while the rest of the surface is not being processed, provides an optimized solution that solves the previously introduced problems regarding current density and uniformity.

[0164] As the surface being transitory processed is reduced compared to a process where the whole surface is processed simultaneously, the amount of sufficient power to be delivered by a current generator to achieve a certain current density is considerably reduced, considerably reducing the device and processing costs.

[0165] A process of scanning of a compacted solid particles wave (707) enables the possibility for the wave being configured specifically for each fraction of the surface being scanned within the treatment. Such configuration favors a processing process free of electrochemical defects, as each area being transitorily scanned is adapted to the respective needs of the area in terms of surface finishing, which in some cases differ from the ones of another area. For this reason, the process described in these particular embodiments offer additional flexibility for being adapted to multiple geometries, materials and shapes.

[0166] In some embodiments, the object being treated (708) is arranged inside the receptacle (704) in such a way that it only comes into contact with the solid particle-based electrolyte (706) through the compacted solid particles pressure wave (707). In this configuration, the surface fraction under treatment is transitorily connected to the pressure wave device (701) only during the oscillatory compaction phase. Such an arrangement lowers the overall power required to achieve the current density necessary for electrochemical surface modification, as only the fraction of the surface in contact through the compacted wave is electrochemically active at a given instant.

[0167] In other embodiments, the surface of the object being treated (708) may be partially immersed in or continuously surrounded by the solid-particle based electrolyte (706), such that contact is not limited exclusively to the compacted wave (707). In this case, both the resting particles and the compacted wave cooperate in the electrochemical exchange, allowing for hybrid treatments where localized polishing or passivation is combined with global conditioning of the surface.

[0168] In yet another embodiment, the object being treated (708) is oriented facing downward inside the receptacle (704), while the pressure wave device (701) cyclically generates an upward- directed compacted pressure wave (707). This geometry ensures that when the compacted wave recedes, residual particles are not left resting on the surface. Such a configuration is particularly advantageous in avoiding corrosive or pitting defects that may arise from unwanted stagnant particle contact after treatment.

[0169] The pressure wave device (701) may incorporate geometrical patterns specifically designed to influence the flow and fractioning trajectory of the solid particles relative to the treated surface. These patterns, may include grooves, ridges, perforations, spiral channels, honeycomb structures, Voronoi tessellations, or fractal roughness surfaces. By engineering the particle trajectories, the system can guide compacted waves into micro-regions of the part, such as corners or edges, where uniform electrochemical treatment is otherwise difficult to achieve. In some particular embodiments, these geometrical patterns are adapted so that the fractioning trajectory of the solid particles is perpendicular to a machining scratch direction that may be present on the surface of the part being treated. This perpendicular trajectory facilitates the efficient removal of scratches or tool marks and improves surface finishing quality.

[0170] In further embodiments, the pressure wave device (701) incorporates means for expelling the fluid present in the interstitial spaces between solid particles of the electrolyte (706). Removal of fluid, such as oils, emulsion, electrolytes, processing vapors, air or intentional additives, leads to an increase in the pressure and packing factor of the electrolyte during compaction, which accelerates the treatment process. For example, the pressure wave device may include a meshed surface that selectively allows fluid expelling while preventing the passage of solid particles, thereby maintaining compaction effectiveness while enhancing local conductivity.

[0171] The pressure wave device (701) itself may adopt different geometrical shapes depending on the processing requirements. Shapes may be triangular, pyramidal, prismatic, conical, spherical, ellipsoidal, toroidal, helical, sinusoidal, Gaussian, parabolic, hyperbolic, catenary, cycloidal, sawtooth, serrated, chevron, cambered airfoil, superelliptical, spline-based, or combinations thereof. The choice of geometry influences the type of wave generated, the pressure profile, and the ability of the compacted particles to reach into specific regions of the surface being treated.

[0172] In a particular embodiment of the invention, a pressure wave device (701) presents a prismatic shape with triangular section or a spherical shape for applying it upon a linear transversal motion with respect to the shape of the wave pressure device. Triangular shape presents a flow of the compacted solid particles pressure wave (707) with respect to the surface being treated that enhances the processing speed in detriment of the final roughness achieved.

[0173] In contrast, in other embodiments, a pressure wave device (701) presents a prismatic shape with circular section or a spherical shape for applying it upon a linear transversal motion with respect to the shape of the wave pressure device. Circular shape presents a flow of the compacted solid particles pressure wave (707) with respect to the surface being treated that enhances the achievement of a lower roughness value in detriment of the processing speed.

[0174] In other embodiments where the transmitted motion is not linear but a combination of at least two linear motions, such as resulting on a circular motion, a pressure wave device (701) presents a pyramidal shape or conical shapes. A revolution profile may create a smoother flow of the compacted solid particles pressure wave (707) with respect to the surface being treated resulting on a lower final roughness; and non-revolution profiles offer higher processing speed in detriment of the final roughness achieved.

[0175] For the treatment of surfaces that include recesses, holes, or complex concavities, the pressure wave device (701) may be further equipped with mechanical elements that force the penetration of solid particles into such regions. Examples include brushes, sponges, bristles, pads, rollers, flaps, fins, scrapers, needles, pins, meshes, foams, compliant membranes, resilient protrusions, vibratory actuators, micro-hammers, or combinations thereof. These elements act synergistically with the compacted pressure wave to ensure that even hidden or recessed areas receive uniform electrochemical treatment.

[0176] In some embodiments, the fixing mechanism (702) that connects the pressure wave device (701) with the oscillating means (703) includes elastic or damping mechanisms, such as springs, elastomer joints, or viscous dampers. These mechanisms provide compliance to the system, allowing the pressure wave device to adapt its position relative to variations in the topography of the treated surface. By dynamically adjusting the distance between the pressure wave device (701) and the surface (708), the compacted pressure wave (707) can be maintained under controlled conditions, avoiding excessive stresses or insufficient compaction. These mechanisms facilitate the adaptation of the distance between the fraction of the surface being treated and said pressure wave device (701) to control the condition of the pressure wave (707) transitory connecting said fraction.

[0177] The solid particle-based electrolyte (706), in some embodiments, may comprise mixtures of conductive and non-conductive particles. Non-conductive particles, such as glass beads, polymer microspheres, or ceramic grains, act as moderators of the electrochemical activity by disrupting conductive pathways. In some embodiments, these particles are abrasive, such as alumina, silicon carbide, or zirconia, which enable simultaneous mechanical abrasion and electrochemical polishing. By adjusting the relative concentration, size distribution, and shape of both conductive and inert particles, e.g., an operator or a controller can fine-tune the compaction behavior, conductivity, and surface finishing quality. As well as for combining a mechanoelectrochemical polishing effect.

[0178] In yet another embodiment, the cyclic compacting system (705, 703, 702, 701) is configured to drive the pressure wave device (701) in circular, linear, biaxial, or triaxial motion paths. This flexibility allows scanning of the surface (708) in patterns adapted to the geometry of the part, ensuring uniform treatment over flat, curved, or irregular surfaces. In more advanced configurations, multiple compacting systems may be combined within a single receptacle (704), each scanning along different axes. By synchronizing or sequencing their operation, arbitrary scanning patterns can be achieved, adapting the treatment process to complex three-dimensional surfaces.

[0179] Furthermore, the cyclic compacting system may be adapted to operate the pressure wave device (701) at two or more different linear speeds. By modifying the speed profile, the pressure and packing factor of the generated compacted wave (707) can be dynamically adjusted. In some embodiments, the change of speed occurs within a fraction of an oscillation period, in others across a whole period, and in some cases throughout the entire surface treatment. In all cases, the variation is applied with continuous linear acceleration, avoiding abrupt transitions that could disrupt conductive pathways or damage the treated surface.

[0180] The linear speed-time profile governing these changes may take different mathematical forms. Examples include sinusoidal, triangular, rectangular, trapezoidal, sawtooth, sigmoidal, Gaussian, exponential, logarithmic, hyperbolic tangent, polynomial, spline-based, piecewise- linear, or fractal-modulated functions. By selecting or combining these profiles, the process can be adapted to specific materials and finishing requirements — for instance, smooth sinusoidal modulation for delicate components, or trapezoidal acceleration for robust parts requiring strong compaction.

[0181] In certain embodiments, the invention comprises a conditioning mechanism configured to regulate and adapt the working conditions of the solid-particle based electrolyte and its interaction with the treated surface. Such conditioning may include, without limitation, the control of temperature, chemical composition, viscosity, humidity, solid-to-liquid ratios, particle size distribution, surface charge, and degree of metal ion saturation within the medium. In some embodiments, the conditioning is performed within a recirculation circuit, through which the electrolyte mixture is continuously or intermittently driven, allowing for cooling, filtering, refreshing, or chemical adjustment. In alternative embodiments, conditioning can occur in situ, directly within the receptacle or at the immediate vicinity of the compacting area.

[0182] The ratio between solid particles and liquid phase within the electrolyte represents a configurable parameter that directly affects the packing factor, pressure transmission, tribological behavior, and electrochemical efficiency of the process. Depending on the ratio, the interstitial space between particles may be the three followingly described cases.

[0183] Interstitial spaces fully filled with liquid, resulting in lower pressure and / or packing factor during compaction. This configuration may provide slower processing speeds but often achieves higher precision, lower final roughness, and improved geometry preservation.

[0184] Interstitial spaces partially filled with liquid, creating conditions where capillary bridges, meniscus effects, and surface tension forces significantly increase the cohesion between particles, leading to higher pressure wave intensity, faster material removal, but potentially less control over micro-geometry and roughness.

[0185] Interstitial spaces nearly dry or empty of liquid, where the lubrication effect is minimal and mechanical friction dominates, resulting in aggressive treatment, higher wear of particles, and less geometry conservation, but also faster surface modification.

[0186] The balance between these regimes can be tailored by, e.g., an operator or a controller to find the most suitable compromise between processing speed, surface precision, and energy consumption, according to the requirements of the specific application.

[0187] In certain embodiments where the electrolyte does not contain a sufficient amount of free liquid for pumping or external conditioning, such as in semi-dry or fully dry particle systems, local overheating, particle degradation, or uneven polishing results may occur if no corrective measures are applied. To address this, the invention may incorporate systems for the injection of fresh particles with optimal properties directly at the advancing front of the compacted pressure wave mechanism, while simultaneously providing for the extraction of used or degraded particles. These extracted particles may then be recirculated, reconditioned, or discarded through waste treatment, ensuring continuous process stability and reproducibility.

[0188] EXAMPLES

[0189] Example 1

[0190] In this first example, a cyclic compaction system, similar to the one illustrated in Figure 1 was used. The system has a cylindrical receptacle of 90 millimeters of diameter where a portion of a toothed gear of 24 millimeters od diameter made of C45E carbon steel alloy, with teeth of 9 millimeters depth fit in. The movement of the piece was primarily vertical, with slight motion in the vertical-horizontal-plane, mimicking the movement of a crankshaft.

[0191] The liquid was pumped, creating a compacted particle layer above the cathode. This layer matched the thickness of the piece to be polished, approximately three centimeters. The liquid passed through the cathode, a resin filter, and a support plate with holes for the filter. The liquid was then recirculated back into the receptacle without causing any water jumps, meaning no bubbles were formed.

[0192] The dry electrolyte used for this example was composed by the following phases:

[0193] • The resin phase consisted of 66.9% by weight of Mitsubishi Relite CFH (sulfonated PST- DVB gel) resin, comprising a heterogeneous particle size distribution ranging between 0.3 - 1.1 mm in diameter of sulfonated gel styrene divinylbenzene particles in an acid format after being dried up to get a constant moisture of 27 wt. % with respect to the total weight of the solid bodies.

[0194] • 6.7% by weight of MSA (methanesulfonic acid) at 70% concentration added directly to the previously described resin,

[0195] • 23.7% by weight of hydroseal: a mixture of aliphatic hydrocarbons with a carbon chain between 12-15 C containing less than 2% of aromatic groups, and

[0196] • 2.7% by weight of octanoic acid 90 - 99 % purity.

[0197] The solid particle-based electrolyte, well-moistened with the added liquid components, is added to the receptacle so that it occupies sufficient height to submerge the part of the piece to be polished. A liquid phase should be added until there is a supernatant of about 10 centimeters above the resin, ensuring no air enters the pump during recirculation. Said liquid phase consisted of:

[0198] • 89.9% by weight of hydroseal

[0199] • 10.1 % by weight of octanoic acid 90 - 99 % purity.

[0200] In this case, the ratio was 31.3% by weight of resin and 68.7% by weight of the liquid phase.

[0201] The process involved turning a pump on for five to seven seconds (during which the resin is compacted, and the piece is simultaneously processed by a periodic vertical movement with an amplitude of 4 cm and a period of 0.5 s ending at its down position to the compacted medium) and then stopping it for one to two seconds (during which the piece is removed, and the medium is renewed).

[0202] Some different processes including different parameters were performed: The first process was conducted under 35 volts for 5 minutes, with direct current and a diode bridge. The intensity that gone through the gear was about 0.1 amperes through a surface of 50 cm2, obtaining a homogeneous surface as a result.

[0203] Ten milliliters of distilled water were added. After adding this amount of water, the same test was conducted but putting the voltage at 25 volts for 5 more minutes where it showed 0.1 amperes. A similar result was achieved, but with greater speed and lower voltage.

[0204] Finally, the voltage was reduced to 20 volts for 10 minutes, with a current of 0.8 amperes on the same geometry. This polishing process was slower, although the piece achieved a higher level of brilliance than the ones mentioned in this example

[0205] Example 2

[0206] In this second example, a cyclic compaction system similar to the one shown in Figure 3 was used. The electrolyte container was designed in the shape of a right triangle, with the right angle positioned as the base. To prevent it from toppling, two columns are positioned at the other two corners of the triangle, extending down to the ground. This design ensures that the entire structure remains stable and solid. The triangular structure has sides measuring 41 centimeters and a hypotenuse of 56 centimeters.

[0207] In the system, a complete gear made of C45E carbon steel alloy with a tooth depth of 4 mm was placed. When the motors for both rotational axes, the cathode and the piece to be polished were activated. The distance between the two rotation axes, the one for the piece and the cathode, was 60 mm. The gear had a tip diameter of 90 mm, with a cathode diameter of 85 mm. The perpendicular walls to the cathode, designed to maintain the compacted layer, measured 122 mm. Free solid particles situated at the vertex of the receptacle were distributed by inertia around the cathode, forming a compacted layer through which each tooth of the gear passed.

[0208] The composition of the electrolyte used was the same as in Example 1 , although the solidliquid ratio varied due to the different container shape. In this case, the ratio was 33.3 % by volume of the resin and 66.7% by volume of the liquid phase.

[0209] The polishing process was conducted under specific parameters to achieve the desired results. The voltage was set at 20 volts, with a current of 0.30 amperes. The rotational speed of the gear was maintained constant at 50 rpm, ensuring consistent exposure of the gear teeth to the compacted particle layer. The total polishing time for this process was 10 minutes, during which the system operated continuously to allow for uniform polishing across the entire surface of the gear.

[0210] Example 3

[0211] In this third example, a cyclic compaction system similar to the one in Figure 2 was used. The difference in the setup was that the movement along the horizontal-axis, that is, the longitudinal piece-electrolyte movement was achieved by moving the electrolyte container. The arm only performed a vertical movement, raising and lowering the piece. The samples polished were carbide punches made of tungsten carbide with cobalt alloy.

[0212] In this cyclic compaction system, the resin is compacted onto the cathode through the liquid recirculation system. During this process, the piece moves up and down three times while the receptacle shifts to the left at a speed of 1 cm / s, ensuring that no two contacts occur on the same surface of the electrolyte. This improves contact between the piece and the electrolyte surface. The movement of the receptacle and the piece ensures that no part of the piece repeatedly contacts the same spot on the electrolyte, thus enhancing the overall polishing or compaction process across the entire surface of the piece. When the receptacle reaches the end of its path, the pump stops, and the container returns to its initial position. This decompresses and slightly mixes the electrolyte. Then, the process is restarted.

[0213] In this third example, different electrolyte compositions were used:

[0214] 1) A first composition used Mitsubishi Relite CFH resin which is a gel type strongly acidic cation exchange resin characterized by a high DVB content, either 100% or mixed in a 10:1 ratio with micro gel resin, with resin thoroughly washed to minimize acid contamination — through five washes by boiling. A liquid phase, added covering the particles, leaving a half-centimeter of supernatant consisted of:

[0215] • 10% ethylene glycol.

[0216] • 90% of distilled water.

[0217] A mixture was well-stirred, and basic ammoniated resin was added at 0.6% of resin weight, then allowed to rest for at least 30 minutes to allow the basic resin to take effect.

[0218] 2) The second composition used the same resin as the first electrolyte medium described, either 100% or mixed in a 10:1 ratio with micro gel resin, similarly washed to reduce acid contamination. The liquid phase, added as needed, was composed of:

[0219] • 10% ethylene glycol,

[0220] • 10% isopropanol,

[0221] • 80% of distilled water.

[0222] Mixture was thoroughly mixed, and basic ammoniated resin was added at 0.6% of the resin weight, followed by a 30-minute rest period.

[0223] 3) The third composition involved using 100% crushed resin, excluding the "fines," which are smaller particles that could pass through the system's filters. These small particles remain suspended in the liquid and can therefore be removed by decantation. This process is repeated twenty times to ensure that all suspended particles are completely removed. The abundance of fines contributes to the ionic nature of the liquid, as these tiny particles would remain suspended in the liquid. To remove the fines, identified as suspended particles in the liquid phase, a decantation process was performed.

[0224] The system filters used were a screen mesh with 16 threads per linear centimeter for dry resin and 62 threads for the crushed resin, though these numbers were not strictly adhered to.

[0225] The solid-liquid ratio of the electrolytes varies depending on the cyclic compaction system used. In this particular system, an amount of resin is added to cover the entire piece and the area to be polished, and then the liquid is added until it extends 1 to 2 cm above the solid layer.

[0226] The parameters and polishing times for the different samples were adjusted to achieve desirable polishing results. For each sample, the voltage, current, and time parameters were varied to determine the best conditions:

[0227] A) For the tests conducted with the first electrolyte with tungsten carbide with cobalt samples, a potential of +20V and -60V was applied, with pulse durations of 5 ps for the positive pulse, 25 ps for the negative pulse, and 5 ps for pauses.

[0228] B) For the second electrolyte, a voltage of +30 - 35V and -60V was applied, with pulse durations of 20 ps for the positive pulse, 100 ps for the negative pulse, and 5 ps for pauses.

[0229] C) The electrolyte containing the crushed particle was subjected to the same parameters as those used for the first electrolyte.

[0230] For the treated piece, a cumulative process was carried out using a combination of different electrolytes and parameters. With the first and second electrolytes mentioned before, 30-minute processes were performed for each, and finally, with the electrolyte containing crushed resin, the piece was polished for an additional hour.

Claims

CLAIMS1. A system for treating surfaces through ion transport, comprising: at least one electrically conductive device; an electrical power supply configured to provide a voltage between an anode and a cathode; an electrical connection system connecting the anode to a positive pole of the electrical power supply and the cathode to a negative pole of the electrical power supply; a fixing system configured to hold a metal part of an object with a surface to be treated to a first pole of the electrical power supply, and at least one electrically conductive device to a second pole; a receptacle for holding a solid-particle based electrolyte the at least one surface being treated and the at least one electrically conductive device; means for generating a relative movement between a surface to be treated of the metal part and the solid-particle based electrolyte when held in the receptacle; a compression system configured to compact free electrically conductive solid bodies of the solid-particle based electrolyte in contact with the surface to be treated and the at least one electrically conductive device.

2. The system of claim 1 , wherein the compression system comprises a mechanism configured to compact free solid bodies in cyclic manner.

3. The system of any one of the preceding claims, wherein the means for generating the relative movement comprises: a movable receptacle including means for linear or rotational movement; one or more arms to hold the workpiece or workpieces, allowing vertical, longitudinal, or circular motion; and one or more cathode systems, that move in at least one axis, including vertical, or longitudinal, or rotational movement while the sample remains fixed.

4. The system of any one of the preceding claims, further comprising an object with the surface to be treated.

5. The system of claim 4, wherein the cathode is adapted to a shape of the object.

6. The system of any one of the preceding claims, further comprising the solid-particle based electrolyte comprising the free electrically conductive solid bodies and a fluid.

7. The system of claim 6, wherein a fluid is a liquid.

8. The system of claim 7, further comprising a liquid recirculation system comprising means for expelling the liquid from a receptacle.

9. The system of claim 8, wherein the means for expelling the liquid comprises a mechanism for reversing the fluid circulation direction.

10. The system of any one of claims 6 to 9, further comprising a system configured to compact the solid-particle based electrolyte against the cathode.11 . The system of any one of claims 6 to 10, wherein the free electrically conductive solid bodies comprise spherical solid bodies with a diameter between 10 pm and 10 cm, in particular, between 200 pm and 1 cm, and more in particular between 300 pm and 1.5 mm.

12. The system of any one of the preceding claims, further comprising means for adjusting a compaction force of a compacted solid bodies layer and / or a thickness of said compacted layer.

13. The system of any one of the preceding claims, further comprising means for synchronizing compression and decompression phases of the compression system with electrical pulses of the electrical power supply.

14. The system of any one of the preceding claims, further comprising a filter adjacent to the cathode, designed to prevent passage of resin particles.

15. A method for surface treating a metal part by ion transport, comprising: connecting an electrode to a first pole of an electrical power supply and connecting and fixing a surface to be treated to a second pole of the electrical power supply inside of a receptacle; contacting said electrodes through compressed solid bodies of a dry electrolyte comprising a moderative fluid, by a compressive system; and providing a relative movement between the compressed solid bodies and the surface to be treated.

16. The method of claim 15, wherein the compressive system includes means for generating cyclic compressive forces.

17. A component with improved surface, the component being surface treated with a method of any one of claims 15 or 16.

18. The component of claim 17, wherein the component is a gear.

19. The component of any one of claims 17 and 18, wherein a Ra roughness value at each surface of the component is below 1 pm.

20. The component of any one of claims 17 to 19, comprising: a face with a surface roughness lower than 0.25 micrometers (pm); a crest with a surface roughness lower than 0.39 micrometers (pm); a flank with a surface roughness lower than 0.15 micrometers (pm); and a valley with a surface roughness lower than 0.52 micrometers (pm).

21. A device for surface treating surfaces trough ion transport comprising: a receptacle (704) for holding a solid-particle based electrolyte (706); the solid-particle based electrolyte (706) comprising electrically conductive solid bodies and a fluid; a fixing system (709); an object for being surface treated (708) at least partially arranged inside the receptacle (704) with help of thefixing system (709); a pressure wave device (701); a cyclic compacting system (705, 703, 702, 701) including a fixing mechanism (702) connecting the pressure wave device (701) and means for cyclically oscillating (703) the pressure wave device (701) through said solid particle-based electrolyte (706), wherein the motion of said pressure wave device (701) is configured to generate a compacted solid particles pressure wave (707) that transitorily connects a fraction of a surface of the object being treated (708) and the pressure wave device (701); and an electrical power supply providing a potential difference between a conductive element and the object being treated (708) and thereby enabling ion exchange through the connected solid particles pressure wave(707).

22. The device according to claim 21 , wherein the object being surface treated (708) is configured to only contact the solid particle-based electrolyte (706) through a compacted solid particles pressure wave (707) that transitorily connects a fraction of a surface of the object being treated(708) and the pressure wave device (701).

23. The device according to claim 21 , wherein the object being surface treated (708) is configured to contact both the solid particle-based electrolyte (706) through a compacted solid particles pressure wave (707) that transitorily connects a fraction of a surface of the object being treated (708) and the pressure wave device (701).

24. The device according to any one of claims 21 - 23, wherein the surface treated (708) is configured to be facing downwards along a gravity direction and the pressure wave (707) that transitorily connects upwards a fraction of a surface of the object being treated (708).

25. The device according to any one of claims 21 - 24, wherein the pressure wave device (701) comprises geometrical patterns configured to force a predetermined fractioning trajectory of the solid bodies relative to a fraction of a surface of the objected being treated.

26. The device according to claim 25, wherein the geometrical patterns of the pressure wave device (701) are adapted to provide with a perpendicular fractioning trajectory of the solid particles with respect to a machining scratch direction of machining marks on the at least one surface being treated.

27. The device according to any one of claims 21 - 26, wherein the pressure wave device (701) incorporates means for expelling the fluid for increasing pressure and / or packing factor of the solid-particle based electrolyte (706) and increasing processing speed.

28. The device according to claim 27, wherein the means for expelling comprise a meshed surface that allows for the flow of said fluid while preventing a set of electrically conductive solid bodies to be expelled.

29. The device according to any one of claims 21 - 28, wherein the pressure wave device (701) further includes mechanical elements for forcing penetration of the electrically conductive solid bodies in concavities.

30. The device according to claim 29, wherein the mechanical elements to force the penetration of the electrically conductive solid bodies in concavities are selected from brushes, sponges, bristles, pads, rollers, flaps, fins, scrapers, needles, pins, meshes, foams, compliant membranes, resilient protrusions, vibratory actuators, micro-hammers, or combinations thereof.

31. The device according to any one of claims 21 - 30, wherein the fixing mechanism (702) connecting the pressure wave device (701) and the means for cyclically oscillating (703) comprise elastic and / or dumping mechanisms.

32. The device according to any one of claims 21 - 31 , wherein the solid particle-based electrolyte (706) further comprises non-conductive particles.

33. The device according to claim 32, wherein the non-conductive particles comprise at least an abrasive particle.

34. The device according to any one of claims 21 - 33, wherein the cyclic compacting system (705, 703, 702, 701) is adapted to provide to the pressure wave device (701) with a circular, linear, biaxial or triaxial motion to scan the surface being treated (708).

35. The device according to any one of claims 21 - 34, comprising more than one cyclic compacting systems (705, 703, 702, 701) to scan the surface being treated (708).

36. The device according to any one of claims 21 - 35, wherein at least a cyclic compacting system (705, 703, 702, 701) is adapted to provide the pressure wave device (701) with at least two different linear speeds, thereby enabling the change on the pressure and / or packing factor of the generated the pressure wave (707) with said change of linear speed.

37. The use of device according to claim 36, wherein the cyclic compacting system (705, 703, 702, 701) is adapted to provide said change of linear speed within at least a fraction of the oscillation period with a continuous linear acceleration, wherein said change of linear speed with a continuous linear acceleration include a linear speed-time profile being selected from sinusoidal, triangular, rectangular, sigmoidal, Gaussian, fractal-modulated, or combinations thereof.

38. The use of device according to claim 36, wherein the cyclic compacting system (705, 703, 702, 701) is adapted to provide said change of linear speed during at least an oscillation period with a continuous linear acceleration, wherein said change of linear speed with a continuous linear acceleration include a linear speed-time profile being selected from sinusoidal, triangular, rectangular, sigmoidal, Gaussian, fractal-modulated, or combinations thereof.

39. The use of device according to claim 36, wherein the cyclic compacting system (705, 703, 702, 701) is adapted to provide said change of linear speed is performed during all the surface treatment with a continuous linear acceleration, wherein said change of linear speed with a continuous linear acceleration include a linear speed-time profile being selected from sinusoidal,triangular, rectangular, sigmoidal, Gaussian, fractal-modulated, or combinations thereof.

40. A method for surface treating a surface through ion transport, the method comprising: providing a receptacle containing a solid-particle based electrolyte; arranging an object having a surface to be treated at least partially within said receptacle; cyclically compacting at least a fraction of the solid-particle based electrolyte to generate a compacted pressure wave transitorily connecting a fraction of the surface of the object; applying a potential difference between the surface of the object and a conductive element such that ionic exchange occurs through the compacted pressure wave; and scanning the surface of the object surface fraction by surface fraction during successive compacting cycles.

41. The method according to claim 40, wherein a packing factor of the solid-particle based electrolyte within each compacting cycle is increased by reducing the free volume between particles by between 60% and 1 %, preferably between 5% and 30%, and more preferably between 10% and 20%.

42. The method according to claim 40, wherein a pressure of a surface fraction during compaction increases between 10% and 1000% relative to static conditions, preferably between 20% and 100%, and more preferably between 30% and 50%.

43. The method according to any one of claims 40 to 42, wherein a current density of a surface fraction during compaction increases between 10% and 100% relative to non-cyclic conditions, preferably between 20% and 70%, and more preferably between 30% and 50%.

44. The method according to any one of claims 40 to 43, wherein duration of each compacting cycle of the successive compacting cycles experienced by a surface fraction represents between 0.001% and 20% of the total surface treatment time, preferably between 0.01 % and 1 %, and more preferably between 0.01 % and 0.1 %.

45. The method according to any one of claims 40 to 44, wherein the surface fraction within each compacting cycle represents between 0.1 % and 50% of the total surface, preferably between 1 % and 20%, and more preferably between 5% and 10%.

46. The method according to any one of claims 40 to 45, wherein the cyclic compaction is provided by translation of a solid element through the solid-particle based electrolyte.

47. The method according to claim 46, wherein the translation of the solid element is at a constant velocity.

48. The method according to claim 47, wherein the translation of the solid element is performed at variable velocity comprising at least two different linear speeds, the change of speed being performed with continuous linear acceleration.

49. The method according to any one of claims 40 to 48, wherein the cyclic compaction furthercomprises rotation of the object whose surface is being treated.

50. The method according to any one of claims 40 to 49, wherein the cyclic compaction is made by at least one compacting system selected from pumps, embolus, fleeces, turbines, aerodynamic components, sponges, or combinations thereof.

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