1235results about "Lapping tools" patented technology

A method comprises planarizing a substrate material with a functionalized chemical planarization pad. The functionalized chemical planarization pad includes a plurality of functional groups bonded to a material of the pad. The functional groups are configured to chemically react with the substrate material such that a portion of substrate material bonds to the functional groups. The pad is regenerated by applying a regeneration solution configured to break bonds between the functional groups and substrate material bonded to the functional groups to form removed material. The removed material is complexed in a dissolved complexing agent to form dissolved material in an effluent phase.

An example polishing system, such as an electrochemical mechanical polishing (ECMP) system, includes a polishing pad assembly having a polishing pad. The example polishing system includes a bias source. The example polishing system includes a workpiece carrier operable to bring the semiconductor workpiece into contact with the polishing pad. In some implementations, the polishing pad assembly is operable to provide an electrically conductive path for one or more charge carriers to the bias source.

The invention provides a system and method for inhibiting wafer scratching in double-sided polishing and double-sided polishing equipment. The system comprises: a shunt manifold valve group, which shunts a polishing liquid main flow path into at least three independent branches respectively corresponding to the inner, middle and outer areas of a polishing pad; the at least three online heating units are respectively arranged on each branch to independently heat the polishing solution; the temperature monitoring device comprises at least three temperature sensors which are arranged in different areas and is used for monitoring the temperature of the three areas in real time; and the control system independently regulates and controls the power of each heating unit based on temperature feedback, a preset non-uniform radial temperature gradient is established and maintained on the polishing pad, and the gradient is configured that the temperature of the middle area is not lower than that of the inner area, and the temperature of the inner area is higher than that of the outer area. Thermal deformation of the polishing pad is optimized through partitioned independent temperature control, and wafer scratching is effectively restrained.

The invention relates to the technical field of semiconductors, and discloses a preparation method of a heat-conducting polyurethane polishing pad, which comprises the following steps: coupling a silane coupling agent with a hydroxylated inorganic heat-conducting material, and carrying out condensation reaction on silanol groups in the silane coupling agent and hydroxyl groups in the hydroxylated inorganic heat-conducting material to form Si-O-Si covalent bonds; bridging a hydroxylated inorganic heat-conducting material at one end of a silane coupling agent to obtain an intermediate; the intermediate is an inorganic heat-conducting material modified by a silane coupling agent; mixing the polyurethane prepolymer with the intermediate to form a mixed prepolymer, and curing the mixed prepolymer at a first temperature to obtain heat-conducting polyurethane; or curing the polyurethane prepolymer to obtain polyurethane, carrying out melt blending on the polyurethane and the intermediate at a second temperature, and curing at a first temperature to obtain heat-conducting polyurethane, in the heat-conducting polyurethane, polyurethane is bridged at the other end of the silane coupling agent. Compared with the prior art, the heat transfer and heat conduction performance of the polishing pad is effectively improved.

The invention relates to the technical field of semiconductors, in particular to a device and a method for automatically adjusting the depth of a groove of a 12-inch wafer polishing pan head, and aims to solve the problem that in the prior art, due to fluctuation of the initial thickness of a to-be-processed wafer, the thickness of the to-be-processed wafer is influenced. The polishing process adaptability is poor; the production efficiency is low; and the consistency of the polishing quality is difficult to control. The device comprises an online thickness measuring module, an adjustable groove polishing head module and a system control unit. The polishing head module is internally provided with a flexible hinge coupling type annular segmented array, a micro-drive actuator, a displacement sensing feedback network and a magnetorheological fluid damping locking system. According to the method, the initial thickness of a wafer is measured in a high-precision mode, the depth of a groove is calculated and adjusted in a feedforward mode, accurate execution and locking are achieved, and collaborative polishing and process dynamic compensation are carried out. According to the invention, accurate, rapid and spatially distinguished automatic adjustment of the groove depth of each wafer can be realized, and the automation level, the processing efficiency and the product quality of the polishing process are remarkably improved.

The invention relates to a polishing performance evaluation method and device and a polishing system for improving the polishing performance. The polishing performance evaluation method comprises the steps that the track lengths of all abrasive particles of a polishing disc are obtained; based on the track lengths of all the abrasive particles, calculating to obtain a track average value and a variance; and based on the trajectory average value and the variance, trajectory distribution uniformity is obtained through calculation. The wafer polishing device has the advantages that the rotating motion of the polishing disc unit and the linear motion of the polishing pad unit are combined, so that the wafer polishing uniformity can be improved, the polishing time is shortened, and the polishing efficiency is improved; the rotating motion of the polishing disc unit and the linear motion of the polishing pad unit are combined, so that uneven abrasion of the polishing pad unit can be avoided, the service life of the polishing pad unit is prolonged, and the cost is reduced.

The invention relates to a photoetching ordered microcosmic fixed abrasive polishing pad and a preparation method thereof. Compared with the prior art, the method has the advantages that the to-be-photoetched surface of the substrate is photoetched according to the photoetched pattern, so that the plurality of microscopic grinding columns are orderly distributed and formed on the grinding material base according to the preset distribution and arrangement mode, the distribution shape, direction and position of the microscopic grinding columns on the grinding material base are kept unchanged, and regular distribution and uniform distribution can be presented; the distribution and the size of the micro grinding columns can be adjusted according to the photoetching pattern to meet different polishing requirements, then the micro grinding columns of the substrate are compositely filled with the filling body to keep the stability of the micro grinding columns, and the polishing pad can be suitable for the micro level to meet the requirement of the manufacturing procedure below 5nm, so that the production efficiency is improved, and the production cost is reduced. The microcosmic grinding columns are formed through photoetching to replace traditional grinding particles, the chemical stability of the polishing pad during polishing is improved, the removal rate is increased, the surface roughness is reduced, and the polishing effect of the polishing pad on a polishing product is improved.

The invention discloses adjustable machining grinding equipment, and relates to the technical field of machining. According to the equipment, a multi-dimensional adjusting mechanism is innovatively integrated, a sliding block is driven through a rotatable double-thread lead screw, stepless adjustment of the grinding radius is achieved, and the equipment is suitable for machining of the inner diameters of workpieces of different sizes; and in combination with a dynamic balance weight system, vibration in high-speed grinding is effectively inhibited, and the stability is improved. Meanwhile, a pneumatic-servo cooperative control system is adopted, stepless switching of the grinding pressure in the four stages of light pressure, medium pressure, heavy pressure and fine grinding is supported, the revolution-rotation speed ratio of the grinding disc to the workpiece is synchronously regulated and controlled, and the uniformity of the grinding track is optimized. In addition, the equipment is provided with a PLC program control module and a touch screen interface, 30 sets of technological parameters can be preset and stored, one-key calling is achieved, and the machining efficiency and consistency of complex parts are remarkably improved. According to the design, the adaptability of the equipment to sapphire substrates, gears and hard alloy special-shaped high-hardness workpieces is greatly expanded.

The invention discloses a surface consistency processing method and system for semiconductor parts, and relates to the technical field of semiconductor manufacturing. The method comprises the steps that the thickness of a polishing pad, the depth of a groove, the pH value of grinding liquid and the concentration of grinding materials are uploaded, part surface features are synchronously collected, and a polishing state map is set; generating a compensation vector based on the map in combination with a precision demand; dynamically adjusting a standard polishing path according to the compensation vector, and determining M targets and N adjacent coordinates to form a region unit; and deploying a digital twinborn simulation rehearsal compensation scene, establishing a parameter adaptive mechanism in combination with reinforcement learning, and optimizing regional resource allocation. The technical problems that in the precise polishing process of semiconductor parts, due to traditional fixed path polishing, local polishing is uneven, and the surface consistency is poor are solved, self-adaptive adjustment and surface consistency optimization of area machining precision are achieved through dynamic polishing compensation based on digital twinning and reinforcement learning, and the precision of the semiconductor parts is improved. And the surface appearance uniformity and the polishing efficiency of the part are improved.

The invention relates to the technical field of semiconductor manufacturing, in particular to a photo-assisted catalytic diamond chemical mechanical polishing device, which solves the problems of low photocatalytic efficiency and low processing efficiency in the prior art, and comprises a bracket, a rotating platform and a working turntable for loading diamond wafers are arranged on the bracket, and an annular baffle plate is arranged on the outer side of the rotating platform. The rotating platform and the annular baffle are matched to form a containing groove, an annular polishing pad and a middle ultraviolet light source are arranged on the rotating platform, the middle ultraviolet light source is located in the center of the annular polishing pad, a side edge ultraviolet light source is arranged on the inner side of the annular baffle, and the annular polishing pad and the middle ultraviolet light source both correspond to the working rotary table in position; the containing groove is filled with polishing liquid, and the annular polishing pad, the side edge ultraviolet light sources and the middle ultraviolet light source are all immersed in the polishing liquid. The device has the beneficial effects that the design that the middle ultraviolet light source and the side ultraviolet light sources cooperatively irradiate is adopted, and the promoting effect of photocatalysis on the chemical reaction on the surface of the diamond is enhanced.

The utility model discloses a diamond grinding brush applied to glass and ceramics, and relates to the technical field of diamond grinding brushes, the diamond grinding brush comprises a mounting disc and a diamond brush head, the front surface of the mounting disc is provided with a front positioning groove, the back surface of the mounting disc is provided with a back positioning groove, and the back surface of the diamond brush head is fixedly provided with a connecting plate; a connecting block is fixedly installed on the side, away from the diamond brush head, of the connecting plate, an inserting hole is formed in the inner side of the connecting block, and the side, close to the connecting block, of the diamond brush head is inserted into the inner side of the front positioning groove. By the adoption of the structure, after the clamping spring and one fixing bolt are taken down, the limiting frame is pulled out, and at the moment, the spring in the mounting cavity resets to push the limiting plate to move and drive the insertion block to be separated from the insertion hole of the connecting block, so that the diamond brush head can be conveniently and rapidly disassembled, assembled and replaced.

A pad-surface determination method that can appropriately determine a surface property of a polishing pad including a condition of protrusions formed on a polishing surface of the polishing pad is disclosed. The pad-surface determination method includes: irradiating a target area in the polishing surface with a plurality of lights from a plurality of light emitters at different incident angles; receiving a plurality of reflected lights from the target area by an imaging device; generating a plurality of images corresponding to the different incident angles by the imaging device; and determining the surface property of the polishing pad based on at least one of the plurality of images. A protrusion is formed on the polishing surface in the target area.

The present application relates to a kind of ball mill, comprising: driven rotation lower grinding disc, the upper surface of the lower grinding disc is equipped with spiral groove for placing ball, the spiral groove has the inlet in the center and the outlet at the edge;Driven lifting upper grinding disc, set in the upper of the lower grinding disc, for the ball on the spiral groove is applied pressure;Circulation channel, inside the lower grinding disc is equipped, the circulation channel is communicated the inlet and the outlet;Wherein, the upper grinding disc is opened with the center area of the inlet corresponding avoiding hole, the spiral groove includes the guide section corresponding the avoiding hole and the working section corresponding the upper grinding disc.Ball is polished by the ball mill, in the whole processing, the moving track of all balls, processing times, grinding time is close to complete coincidence, so that smaller ball batch diameter variation can be obtained, eliminate or reduce the original existence screening or again processing.

An integrated cleaning and liquid supply device and online cleaning method for polyurethane polishing pads are disclosed. The device includes a base, a rotating seat, a swing arm, an independent liquid supply pipeline system and cleaning pipeline, a high-pressure nozzle array, and a positioning sensor assembly. During the polishing stage, polishing liquid is dripped through the liquid supply outlet. During the cleaning stage, the swing arm moves centripetally to a preset position aligned with the center of the polishing pad. The positioning sensor triggers a high-pressure pump, causing pure water to be sprayed as an atomized jet along the diameter of the pad surface through the high-pressure nozzle array. Simultaneously, the polishing pad rotates at a low speed, utilizing the synergistic effect of centrifugal force and high-pressure water flow to thoroughly remove residual contaminants within the micropores of the polyurethane. This invention integrates liquid supply and deep cleaning functions into the same motion mechanism, eliminating the need for machine shutdown or manual intervention. It offers advantages such as non-contact, non-destructive, thorough cleaning, and high automation, extending the life of the polishing pad and improving the stability of the CMP process.

The CVD diamond optical grinding process comprises the following steps that S1, surface cleaning is conducted on a selected diamond workpiece to be ground, and grinding discs with different grinding coefficients are selected, S2, the grinding stage is divided into the rough grinding stage and the fine grinding stage, the grinding disc with the finer surface roughness degree is replaced after rough grinding, and the grinding disc with the finer surface roughness degree is replaced after fine grinding. S3, according to the thickness of the diamond, the heights of a plurality of grinding heads are adjusted to adapt to the diamonds with different thicknesses, a first grinding motor and a second grinding motor are started for grinding, and in the grinding process, the limiting assemblies and the grinding assemblies are matched for use, so that the grinding efficiency is improved; and meanwhile, due to the fact that the autorotation direction and the circular motion direction of the grinding head and the second grinding planetary gear are opposite, regular grinding traces generated by traditional single-direction grinding are effectively broken through, and grinding is more uniform.

The invention relates to a polishing pad for polishing a silicon carbide wafer as well as a preparation method and application of the polishing pad. The polishing pad is prepared from the following raw materials in parts by weight: 10 to 15 parts of silicone oil, 25 to 35 parts of polyurethane prepolymer, 1 to 3 parts of anionic chain extender, 0.001 to 0.004 part of first catalyst and 2 to 5 parts of modified organic silicon microspheres. The chitosan quaternary ammonium salt and the cinnamic acid are adopted to modify the epoxy group organic silicon elastomer powder, and the modified organic silicon microspheres with high rigidity and high interface bonding force are prepared, so that the wear resistance and the storage modulus of the polishing pad are remarkably improved, and the requirement for high-precision polishing of silicon carbide wafers is met.

A slurry arm for an associated chemical mechanical polishing (CMP) system for semiconducting wafer substrates includes a slurry arm main body; a plurality of holes disposed along a length of the slurry arm main body; a valve controlling slurry flow through each hole of the plurality of holes; and a controller configured to open or close each valve.

Examples are disclosed that relate to planarizing substrates without use of an abrasive. One example provides a method of chemically planarizing a substrate, the method comprising introducing an abrasive-free planarization solution onto a porous pad, contacting the substrate with the porous pad while moving the porous pad and substrate relative to one another such that higher portions of the substrate contact the porous pad and lower portions of the substrate do not contact the porous pad, and removing material from the higher portions of the substrate via contact with the porous pad to reduce a height of the higher portions of the substrate relative to the lower portions of the substrate. In some examples, linear motion may be used for chemically planarizing.

The present invention relates to a polishing pad including a polishing layer and a cushion layer, wherein a ratio E′B40 / E′C40 of a storage elastic modulus at 40° C. in dynamic viscoelasticity measurement performed under a bending mode condition with a dry state, a frequency of 10 rad / s, and 20 to 100° C., E′B40, to a storage elastic modulus at 40° C. in dynamic viscoelasticity measurement performed under a compression mode condition with a dry state, a frequency of 10 rad / s, and 20 to 100° C., E′C40, is 3.0 or more and 15.0 or less, and a loss factor tan δ in the dynamic viscoelasticity measurement performed under the bending mode condition is 0.10 or more and 0.30 or less in a range of 40° C. or more and 70° C. or less.

The utility model discloses a machining device for a guide fillet of a sealing structure, which comprises a grinding head, abrasive paper and a positioning shaft, and the grinding head is provided with a positioning cylinder and a rotary grinding surface which is formed by taking an inner concave arc R as a contour edge and taking the axis of the grinding head as a rotating shaft. Before a guide fillet is machined, abrasive paper is marked along the contour of a cutting sample plate and cut, then the abrasive paper is pasted to a grinding head through glue, a positioning shaft is inserted into a pipe joint, the grinding head is clamped through a handheld electric drill, a positioning cylinder is inserted into a positioning round hole of the positioning shaft, and the grinding head is pressed to a to-be-machined position for grinding; and finally, metallographic abrasive paper is used for polishing the ground round corner, and alcohol is used for cleaning the ground round corner. By adopting the guide fillet processing device, the problems of difficult repair and low repair qualification rate caused by missing processing of the guide fillet can be solved.

The invention relates to a low-stress chemical mechanical etching process suitable for fragile materials, which belongs to the technical field of etching processing of fragile materials and comprises a precise chemical mechanical polishing machine, a polishing pad, a polishing solution conveying and managing system and end point detection equipment. The precise chemical mechanical polishing machine comprises a multi-zone pressure controllable polishing head, a high-precision rotating speed control system and a real-time thickness measuring system, a polishing pad is a polishing disc made of porous polyurethane materials, and the polishing liquid conveying and managing system comprises a multi-channel metering pump system and a stirring and temperature control unit. And the end point detection equipment comprises a surface profilometer, an atomic force microscope and a transmission electron microscope. According to the method, through fine cooperation of chemical reaction and mechanical grinding, microcrack initiation and propagation in the polishing process are effectively inhibited, surface and subsurface damage of the fragile material is remarkably reduced, the machined surface which is ultrahigh in smoothness and free of damage is obtained, and meanwhile the high material removal rate is kept.

Examples are disclosed that relate to planarizing substrates without use of an abrasive. One example provides a method of chemically planarizing a substrate, the method comprising introducing an abrasive-free planarization solution onto a porous pad, contacting the substrate with the porous pad while moving the porous pad and substrate relative to one another such that higher portions of the substrate contact the porous pad and lower portions of the substrate do not contact the porous pad, and removing material from the higher portions of the substrate via contact with the porous pad to reduce a height of the higher portions of the substrate relative to the lower portions of the substrate.

The invention relates to a high-hydrophilicity CMP hard polishing pad, a preparation method and application thereof, the polishing pad comprises a polishing layer, a fitting layer and a buffer layer, the polishing layer is formed by mixing and pouring a component A and a component B, the component A comprises polyisocyanate, polyol, a foaming agent and a hydrophilic modifier, and the component B is an amine curing agent. The carboxylate is added into the polishing layer to serve as a hydrophilic modifier, and after dissociation, the carboxylate is combined with polar groups in a polyurethane molecular chain through coordinate bonds or ionic bonds to form a stable bonding structure, so that the carboxylate is attached to a main chain of the polyurethane molecular chain, and the overall hydrophilicity of the polyurethane structure is improved. According to the method, the surface energy and surface characteristics of the polishing pad can be changed fundamentally, the introduced hydrophilic auxiliary agent cannot reduce the mechanical property of an original formula, and the constant hydrophilicity is maintained during the polishing service life of the polishing pad.

A polishing pad contains: a polishing layer having a polishing surface for polishing a workpiece; and a cushion layer disposed on the side of the polishing layer opposite from the polishing surface. With regard to the ratio (tan δ) of the storage elastic modulus E′ to the loss elastic modulus E″ of the whole polishing pad, as obtained through dynamic viscoelasticity measurement using frequency dispersion (25° C.) in a bending mode, the ratio of the maximum value of tan δ measured at 100-1000 rad / s (tan δmax100-1000) to the maximum value of tan δ measured at 1 to 10 rad / s (tan δmax1-10) is 0.75 to 1.30.

The present invention relates to techniques for calculating polishing rate responsiveness with respect to a change in the pressure with which a workpiece used for manufacturing a semiconductor device, such as a wafer, a substrate, or a panel, is pressed against a polishing pad. A method of the present invention comprises: calculating by simulation a pressing-pressure responsiveness profile indicating a distribution of pressing-pressure applied from a workpiece to a polishing pad (2) as the pressing-pressure changes in response to a change of unit pressure in a pressure chamber of a polishing head (7); polishing the workpiece by pressing the workpiece against the polishing pad with the interior of the pressure chamber maintained at a predetermined pressure; creating a polishing rate profile indicating a polishing rate distribution of the workpiece being polished; and creating a polishing rate responsiveness profile on the basis of the pressing-pressure responsiveness profile, the predetermined pressure, and the polishing rate profile.

To provide a polishing pad that is excellent in topo performance and polishing rate.SOLUTION: A polishing pad comprises a polishing layer made of a polyurethane resin foam made from an isocyanate-terminated prepolymer and a curing agent. Therein: a ratio of a crystalline phase content to an amorphous phase content (amorphous phase / crystalline phase) in the polishing layer measured at 40°C by a pulsed NMR method in a wet state is 3.0 or more and 4.5 or less; and a ratio of a mesophase content to the amorphous phase content (amorphous phase / mesophase) in the polishing layer measured at 40°C by the pulsed NMR method in the wet state is 6.5 or more and 13.0 or less.SELECTED DRAWING: Figure 1

The invention relates to the technical field of grinding devices, in particular to a cylindrical injection molding part grinding device which comprises a grinding platform and a lower grinding disc installed at the top of the grinding platform, an upper grinding disc is installed at the top of the lower grinding disc, a cleaning structure is arranged at the top of the grinding platform, and a plurality of positioning plates for supporting workpieces are installed at the top of the lower grinding disc. By adopting the composite design of the slidable and rotatable cleaning cylinder, the peripheral cleaning brush and the internal negative pressure cavity, the cleaning brush is made of a flexible wear-resistant material, can rotate and slide along with the cleaning cylinder, goes deep into microcosmic lines and blind areas of a grinding disc, and mechanically peels off stubborn grinding dust, and meanwhile, the dust suction pump works to form negative pressure in the cleaning cylinder, so that the cleaning effect is improved. Scraped abrasive dust and grinding liquid are sucked synchronously through the peripheral dust suction holes, secondary attachment of the abrasive dust is avoided, the cleaning efficiency is improved, the secondary scratch rate of workpieces is reduced, the grinding and cleaning procedures are automatic, and all-region dead-corner-free cleaning of the abrasive dust is achieved.

The invention discloses a double-layer foaming porous polishing pad as well as a preparation method and application thereof, and relates to a double-layer pore structure chemical mechanical polishing pad, the upper part of a polishing layer of the polishing pad is provided with closely distributed finger-shaped pores, the average inner diameter is 0.17-0.25 mm, and the pore wall thickness of the finger-shaped pores is 15-20 microns; the lower part of the polishing layer is a sponge hole layer, and the average inner diameter of the sponge hole layer is 5-10 microns; the main body structure of the polishing layer is prepared from coating slurry comprising polyurethane resin, polyvinyl chloride resin and ethyl acetate in a coagulating bath through a non-solvent phase inversion method. The rebound rate of the polishing pad can be effectively improved by controlling the relative thickness of the double-layer holes of the polishing layer, the abrasion resistance of the polishing pad is remarkably improved through resin blending, the service life is prolonged, meanwhile, the hardness of the polishing layer is moderate, and product defects are effectively reduced. The polishing pad has excellent wear resistance and moderate hardness, the service life is remarkably prolonged, particle defects in the polishing process are reduced, and the polishing pad is suitable for a high-precision polishing process.

The utility model relates to a polishing system of a germanium single crystal wafer for a high-flatness ultra-thin solar cell, which comprises a rough polishing mechanism, a rough polishing mechanism and a polishing mechanism, the rough polishing mechanism comprises a rough polishing machine fixed disc, rough polishing cloth arranged on the upper end face of the rough polishing machine fixed disc, a rough polishing grinding head arranged above the rough polishing machine fixed disc, and a rough polishing ceramic disc arranged at the grinding end of the rough polishing grinding head; the semi-fine polishing mechanism comprises a semi-fine polishing machine fixed disc, semi-fine polishing cloth arranged on the upper end face of the semi-fine polishing machine fixed disc, a semi-fine polishing grinding head arranged above the semi-fine polishing machine fixed disc and a semi-fine polishing ceramic disc arranged at the grinding end of the semi-fine polishing grinding head. The fine polishing mechanism comprises a fine polishing machine fixed disc, fine polishing cloth arranged on the upper end face of the fine polishing machine fixed disc, a fine polishing grinding head arranged above the fine polishing machine fixed disc and a fine polishing ceramic disc arranged at the grinding end of the fine polishing grinding head. By means of rough polishing, surface attachments and stains can be removed, machining allowance can be rapidly removed, efficiency is improved, and size control and flatness can be gradually achieved through semi-fine polishing and fine polishing.

This invention discloses a grinding tool for a high-rigidity precision mold guide post, relating to the field of guide post grinding technology. It includes a grinding assembly for grinding the guide post and checking its dimensional accuracy. The grinding assembly comprises a grinding component, a support switching component, and an inspection component. The grinding component grinds the guide post, the support switching component clamps and switches the positions of the two guide posts, and the inspection component checks the grinding status of the guide post. The grinding component includes a fixed stage and a moving stage. The support switching component is mounted on the moving stage, and the inspection component is mounted on the fixed stage. Through the operation of the grinding assembly, two guide posts can operate in parallel with station switching, allowing grinding and inspection of the guide posts to be performed simultaneously. A single guide post can quickly switch between grinding and inspection positions, ensuring that one guide post is always being ground while another is being inspected. This utilizes the idle time of existing grinding processes, improving the production efficiency of guide post grinding.