Laser and foil based additive manufacturing systems and methods

Abstract

A method and system for additive manufacturing is disclosed. In one example, the method includes the steps of: (a) positioning a foil layer on a substrate, (b) laser welding the foil layer to the substrate, (c) laser ablating the foil layer using a pulsed laser beam to remove at least a portion of the foil layer, the pulsed laser beam including optical pulses having a pulse duration in the range of 0.5 picoseconds (ps) to 10 ps inclusive, and (d) repeating steps (a)-(c) until the 3D part is completed.

Description

[Technical field]

[0001] Related Applications This application claims priority to U.S. Provisional Application No. 63 / 305768, filed February 2, 2022, and entitled "LASER AND FOIL BASED ADDITIVE MANUFACTURING SYSTEM AND METHOD," the contents of which are incorporated herein by reference in their entirety.

[0002] The technical field relates generally to additive manufacturing methods, and more particularly to the use of laser energy to treat successive foil layers in an additive manufacturing process. [Background technology]

[0003] Additive manufacturing (AM) processes are evolving into an entirely new industry for creating three-dimensional (3D) solid objects by adding individual layers of material. Two AM processes that use lasers include laser metal deposition (LMD) and selective laser melting (SLM). Another laser technique is known as stereolithography (SLA), which uses a shorter wavelength laser to locally photopolymerize a liquid. All of these techniques use layers of powder that are regenerated after each layer is laser melted. In another laser technique, called LMD, powder is fed coaxially through a nozzle into a focused laser spot to create fully dense functional metal parts.

[0004] Powder-based AM processes have several drawbacks. For one, these processes are slow, e.g., they take hours or days to complete a part, and are therefore used for short or single runs of unique parts. One reason powder AM processes are slow is that the parts require additional processing beyond the initial laser sintering (i.e., post-processing steps). Metal powders are also expensive and not easily reused. Thus, there is a need for an AM process system that can quickly and inexpensively create large quantities of 3D parts. Summary of the Invention [Means for solving the problem]

[0005] Aspects and embodiments are directed to methods and systems for additive manufacturing of 3D parts.

[0006] According to an exemplary embodiment, a method for AM of a three-dimensional (3D) part is provided, the method including the steps of: (a) positioning a foil layer on a substrate, (b) laser welding the foil layer to the substrate, (c) laser ablating the foil layer to remove a portion of the foil layer using a pulsed laser beam, the pulsed laser beam including light pulses having a pulse duration in the range of 0.5 picoseconds (ps) to 10 ps inclusive, and (d) repeating steps (a)-(c) until the 3D part is completed.

[0007] In one example, the light pulse has a pulse energy between 25 microjoules (μJ) and 200 (μJ), inclusive.

[0008] In one example, each pulse of the pulsed laser beam has a peak power of at least 1 Megawatt (MW).

[0009] In one example, laser welding is performed using a laser beam obtained from at least one of a continuous wave (CW) laser source and a quasi-continuous wave (QCW) laser source, the method further comprising providing at least one of a CW laser source and a QCW laser source. In a further example, at least one of the CW laser source and the QCW laser source is configured to have an output power of at least 1 kW. In a further example, at least one of the CW laser source and the QCW laser source is configured to have an output power of at least 5 kW.

[0010] In one example, the method further comprises receiving a foil layer, the foil layer being wound as a roll of foil material. In a further example, the foil layer is up to and including 1 millimeter (mm) in thickness. In a further example, the foil layer comprises a metallic material. In a further example, laser welding and laser ablation are performed in the treatment area, and the method further comprises unrolling the foil layer in one direction from the roll and guiding the foil layer to the treatment area.

[0011] In one example, the method further includes lowering a build platform supporting the substrate prior to step (a) by moving it in a z-axis direction, the z-axis direction being oriented in a plane perpendicular to the build platform.

[0012] In one example, welding is performed in the z-axis direction and laser ablation is performed in the x- and y-axis directions.

[0013] In one example, the method further includes performing the laser welding and laser ablation in an atmospherically controlled build chamber configured to at least partially contain an inert gas.

[0014] In one example, laser welding and laser ablation are performed in the processing region and the method further includes delivering an inert gas to the processing region.

[0015] According to another exemplary embodiment, an AM system for forming a 3D part from multiple successive foil layers is provided, the AM system includes a welding laser configured to generate a laser beam capable of welding the foil layer onto a substrate, an ablation laser configured to generate a pulsed laser beam capable of ablating at least a portion of the foil layer, the pulsed laser beam including optical pulses having a pulse duration in the range of 0.5 ps to 10 ps inclusive, and a controller used to successively build the 3D part, the controller configured to receive build instructions for each foil layer including welding energy information and ablation energy information for each foil layer, and to send control signals to each of the welding laser and ablation laser such that the welding laser provides welding laser energy corresponding to the welding energy information for each foil layer and the ablation laser provides ablation laser energy corresponding to the ablation energy information for each foil layer.

[0016] In one example, the build instructions include at least one of x-position data, y-position data, and z-position data associated with each of the welding energy information and the ablation energy information, and the controller is further configured to control at least one of a position of the welding laser and a position of the ablation laser in at least one of an x-axis direction, a y-axis direction, and a z-axis direction based on the x-position data, the y-position data, and the z-position data.

[0017] In one example, the controller is further configured to control a foil feed system, the foil feed system configured to guide the foil layer to the processing area.

[0018] In one example, the foil layer is wound as a roll of foil material, and the foil delivery system is further configured to unroll the foil layer in one direction from the roll.

[0019] In one example, the welding laser is configured to perform welding along a z-axis oriented in a plane perpendicular to the treatment area.

[0020] In one example, the AM system further includes an inert gas delivered to the processing region.

[0021] In one example, the ablation laser is configured to remove foil layer material in at least one of the x-axis and y-axis directions.

[0022] In one example, the welding laser is configured to have an output power of at least 1 kW. In a further example, the welding laser is configured to have an output power of at least 5 kW.

[0023] In one example, the welding laser includes at least one of a continuous wave (CW) laser source and a quasi-continuous wave (QCW) laser source.

[0024] In one example, the ablation laser is configured such that each pulse of the pulsed laser beam has a peak power of 1 Megawatt (MW).

[0025] In one example, at least one of the welding laser and the ablation laser is configured as a fiber laser.

[0026] In one example, the AM system further includes an atmospherically controlled build chamber configured to at least partially contain an inert gas and surround the welding laser beam and the ablative laser beam.

[0027] In one example, the foil material is a metallic material having a thickness of up to 1 mm.

[0028] Further aspects, embodiments, and advantages of these exemplary aspects and embodiments are described in detail below. Moreover, it should be understood that both the above information and the following detailed description are merely illustrative examples of various aspects and embodiments, and are intended to provide an overview and framework for understanding the nature and characteristics of the claimed aspects and embodiments. The embodiments disclosed herein may be combined with other embodiments, and terms such as "an embodiment," "an example," "some embodiments," "some examples," "alternative embodiments," "various embodiments," "one embodiment," "at least one embodiment," "this and other embodiments," "an embodiment," and the like are not necessarily mutually exclusive, but are intended to indicate that a particular described feature, structure, or characteristic may be included in at least one embodiment. Appearances of such terms in this specification do not necessarily all refer to the same embodiment.

[0029] Various aspects of at least one embodiment are described below with reference to the accompanying figures. The figures are not intended to be drawn to scale. The figures are included to enable illustration and further understanding of the various aspects and embodiments, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of particular embodiments. The drawings, together with the remainder of the specification, serve to explain the principles and operation of the described and claimed aspects and embodiments. In the figures, each identical or nearly identical part shown in the various figures is represented by the same numeral. For clarity of illustration, not every part has been identified in every figure. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a block diagram of an example of an additive manufacturing (AM) system according to an aspect of the present invention. [Figure 2A] FIG. 2 is a block diagram of an example of a welding process to a foil layer using a laser of the AM system of FIG. [Figure 2B]FIG. 2B is a block diagram of an example of an ablation process on the foil layer of FIG. 2A using the laser of the AM system of FIG. 1. [Diagram 3] FIG. 1 is a schematic diagram of an incremental build process in which each foil layer is successively added to construct a 3D part according to an embodiment of the present invention. [Figure 4] FIG. 2 is a block diagram of an example of a 3D part being built by the two lasers of the AM system of FIG. [Diagram 5] FIG. 2 is a schematic diagram of an example of an advancing layer of foil material in a continuous process according to an embodiment of the present invention. [Figure 6] FIG. 2 is a schematic diagram of another example of advancing layers of foil material in a continuous process according to an embodiment of the present invention. [Figure 7] 1 is a flow chart illustrating steps and decision blocks of a method for additive manufacturing in accordance with an aspect of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] As mentioned above, cost and throughput are two of the biggest problems with powder-based AM processes and systems. Powder-based systems are traditionally used for modeling and low volume applications, such as the aviation and medical industries. Disclosed herein are foil-based AM systems and methods using lasers that address many of the problems with powder-based AM processes. The disclosed systems and methods are significantly faster than powder-based AM systems, e.g., 100 times faster, and can be implemented in continuous, high volume manufacturing applications. In addition, foil-based AM techniques do not require post-processing procedures as do powder-based AM techniques. As described in more detail below, foil layers are added to a substrate sequentially, and each foil layer is exposed to two separate laser treatments. The first laser treatment welds the foil material, and the second laser treatment ablates the foil material. Unlike powder-based AM processes, foil materials are less expensive than powder materials and are much easier to reuse. In addition, 3D parts with low weight and / or porous structure can be built using foil layers, which is not necessarily true for powder materials. Foil materials are also safer to use than powders, which are generally microscopic in size (<100 μm) and often carry associated hazards related to toxicity, reactivity, flammability, and instability.

[0032] 1, there is shown a block diagram of a non-limiting example of an AM system generally designated 100. The AM system 100 includes a welding laser 120, an ablation laser 110, and a controller 150.

[0033] The welding laser 120 is configured to generate a laser beam 122 (also referred to herein as a welding laser beam) capable of welding the foil layer 105 onto the substrate 132. In some embodiments, the substrate 132 is positioned on the build platform 130. It should be appreciated that according to some embodiments, the substrate 132 is a previous foil layer, and in some examples (e.g., at the start of the AM process), the substrate 132 may be a 2D or 3D build substrate that is later removed.

[0034] As used herein, the term foil layer refers to a thin, flexible film or sheet of any material, for example, from about 10 μm to about 1 mm in thickness, although thicker materials are within the scope of the present disclosure. In some embodiments, the foil layer is up to 1 millimeter (mm) in thickness, including 1 mm itself. It should be appreciated that the foil layer may have any thickness that is amenable to the disclosed processes to build the desired 3D part. According to some embodiments, the foil layer comprises a metallic material. Non-limiting examples of metallic materials suitable for the disclosed AM systems and processes include aluminum, steel, and steel alloys, nickel, titanium, copper, tin, cobalt, nitridium, tantalum, Inconel, and other metallic materials and any alloys. According to other embodiments, the foil layer comprises a polymeric material. Non-limiting examples of polymers that may be suitable for the disclosed methods and systems include polypropylene, polyethylene, polystyrene, polyvinyl alcohol, polyester, polyimide, and other polymer-based materials. Other materials and composites are also within the scope of the present disclosure.

[0035] Welding of the foil layer 105 using a welding laser 120 (also referred to as a welding laser source) serves to attach the foil layer 105 to the underlying substrate 132. A schematic diagram of one example of this process is shown in FIG. 2A. The laser beam 122 of the welding laser 120 is delivered to the surface of the foil layer 105 and applies sufficient laser energy to the underlying substrate 132 (in this example, the substrate 132 is the previous foil layer) to weld the foil layer 105. The welded areas are shown in FIG. 2A as black circles. According to some embodiments, the welding laser 120 is configured to have an output power of at least 1 kilowatt (kW), in some embodiments, an output power of at least 5 kW, and in still other embodiments, an output power in the range of 5 to 10 kW (including 5 kW and 10 kW itself). Output powers less than 1 kW are also within the scope of the present disclosure, since lower welding powers may be required or desired in some applications.

[0036] In at least one embodiment, laser welding is performed using a laser beam obtained from at least one of a continuous wave (CW) laser source and a quasi-continuous wave (QCW) laser source. According to one embodiment, the CW laser is configured to generate a single mode (SM) laser beam with a spot size in the range of up to 10 μm, although a smaller spot size can be achieved by having a focal length of less than 200 mm. The quasi-continuous wave (QCW) laser comprises a switched pump laser source that is switched on for a period short enough to reduce thermal effects and remains switched on for a period long enough to maintain a continuous wave output. In the configuration of the QCW laser source, the number of pump diodes that are bonded as active fibers is increased. A low duty cycle (e.g., 1-15%, inclusive) is implemented, which requires a smaller power supply, but in pulsed mode the laser provides up to 10 times higher peak power compared to the output power in CW mode. For example, a CW laser may be configured to have an average output power of 600 Watts (W) and a QCW laser may be configured to have a peak power of 6000 W. Essentially, QCW provides high peak power for a short duty cycle. QCW lasers can be configured to provide multiple Joules of pulse energy at multiple kW peak power with microsecond (μs) to millisecond (ms) pulse durations. CW and QCW lasers can be used to perform different types of welding processes. For example, QCW lasers can be modulated to minimize, i.e., reduce, the heat input to the part during laser processing. QCW lasers may be particularly useful for applications requiring high peak power and pulse energy in a long pulse regime, such as spot welding and seam welding. Examples of suitable CW and QCW welding lasers can be obtained from IPG Photonics, Oxford, Massachusetts, USA.

[0037] According to some embodiments, the welding of the foil layer 105 may be performed in multiple steps, and in some examples, the welding may be performed using multiple welding lasers or a single laser, each of which may be configured to operate in different modes. In one embodiment, a first welding laser may be configured to generate a laser beam suitable for performing a bulk welding process using high power and a large spot size. Bulk welding may be used to quickly weld larger surface areas. A second welding laser may be used to perform precision welding. Precision welding may be performed for areas that require higher precision (e.g., corners, edges of the topography). The output power and spot size of the laser beam used for each type of welding application may differ from each other and depend on the material and configuration of the 3D part. With regard to timing, either type of welding may be performed before the other or simultaneously with the other, depending on the application and laser configuration. For example, in some embodiments, a spot welding may be performed first, and then a different type of welding may be performed second.

[0038] The ablation laser 110 is configured to generate a pulsed laser beam 112 (also referred to as an ablative laser beam) capable of ablating at least a portion of the foil layer 105. The pulsed laser beam 112 comprises optical pulses having a pulse duration in the range of 0.5 ps to 10 ps (inclusive). According to one embodiment, the optical pulses have a pulse duration of 1 ps. In some embodiments, the optical pulses have a pulse duration of 1 to 3 ps (inclusive) and a pulse frequency in the range of 50 to 2000 kHz (inclusive). Referring now to FIG. 2B, a schematic diagram of one example of an ablation process is shown. The laser beam 112 of the ablation laser 110 is directed to the surface of the foil layer 105, applying sufficient laser energy to ablate at least a portion of the foil layer 105. The foil layer 105 is shown as a black ring in FIG. 2B. The ablative laser energy is absorbed by the foil material, which evaporates, vaporizes, or sublimes. In the example of Figure 2B, a central region of the black ring has already been welded (designated as region "A") using the welding laser 120 in Figure 2A. After ablation, the outer foil material of the black ring (designated as region "B") has separated from the welded region "A". Region "B" may then be removed (e.g., sent for recycling) from the vicinity of the work area associated with region "A".

[0039] There are two broad classes of laser ablation: thermal and non-thermal. Thermal ablation relies on thermal effects such as melting and is not the type of ablation induced by the ablative laser 110 described herein. Non-thermal ablation can occur when an ultrashort pulse is focused on a material as a result of a high electric field associated with the ultrashort pulse and is the type of ablation induced by the ablative laser 110. Material removal induced or otherwise caused by non-thermal ablation has several advantages when compared to other conventional material removal methods such as machining. For one, non-thermal ablation allows for precise removal of material without mechanical damage to the surrounding material. Pulses longer than the ps level (e.g., >1 ns) and laser energy available from CW lasers also damage the surrounding material. Examples of suitable ablative lasers can be obtained from IPG Photonics, Oxford, Massachusetts, USA.

[0040] Besides removing material, the ablation laser 110 can be used to perform display treatments / functionalizations on the foil layer, such as texturing, patterning, etc. This is an added advantage over powder-based AM systems, since such high precision techniques cannot be applied without additional equipment.

[0041] According to at least one embodiment, the optical pulses of the pulsed laser beam 112 have a pulse energy between 25 microjoules (μJ) and 200 (μJ), inclusive. According to another embodiment, each pulse of the pulsed laser beam 112 has a peak power of at least 1 Megawatt (MW). In some embodiments, the peak power can range from 25 to 50 MW. For example, according to one non-limiting example, the optical pulses have a duration of 1 ps, a pulse energy of 25 μJ, and a peak power of 25 MW.

[0042] According to some embodiments, at least one of the welding laser 120 and the ablation laser 110 is configured as a fiber laser. Fiber laser refers to a laser having a doped fiber as the gain medium, but also refers to a laser in which the majority of the laser cavity is made of optical fiber.

[0043] 1 , according to at least one embodiment, the foil layer 105 is wound as a roll of foil material 107. The roll of foil material 107 may be guided or otherwise delivered to a substrate 132 and / or a processing area 135 (where at least one of laser welding or laser ablation energy is applied to the foil layer 105) using a foil feed system, shown generally as 115 in FIG. 1 . In some embodiments, the foil feed system guides the foil material to a build platform 130, which serves to support the substrate 132. The foil layer 105 is unwound in one direction from the roll 107 by the foil feed system 115. In some embodiments, the foil layer 105 is guided along the build platform 130.

[0044] The foil layer 105 is processed by the welding laser 120 and the ablation laser 110 as it is conveyed to the substrate 132 and / or the processing area 135. The roll of foil material 107 is fed or otherwise guided to the substrate 132 and / or the processing area 135 so that successive layers of foil material are laser processed to form a 3D part. According to some embodiments, the foil delivery system 115 is configured to guide the foil layer 105 to the substrate 132 and / or the processing area 135 in at least one of an x-axis and a y-axis. FIG. 1 includes a reference coordinate system, which comprises three orthogonal axes including a longitudinal axis or x-axis, a transverse axis or y-axis, and a vertical axis or z-axis. In the example of FIG. 1, the roll of foil material 107 is fed in the x-axis direction.

[0045] The AM system 100 also includes a controller 150, as shown in FIG. 1. According to at least one embodiment, the controller 150 is configured to receive build instructions for each foil layer 105 used to successively build the 3D part. The build instructions include welding energy information and ablation energy information for each foil layer. For example, the welding energy information includes the required laser energy to weld the foil layer 105 to the underlying substrate (assuming a welding laser configuration), and the ablation energy information includes the required laser energy to ablate the foil layer 105 (assuming an ablation laser configuration). The energy information is used by the controller 150 to send control signals to each of the welding laser 120 and the ablation laser 110 such that each laser provides the desired laser energy to each foil layer 105.

[0046] The build instructions may include at least one of x, y, and z position data associated with each of the welding energy information and ablation energy information for each layer. For example, the build instructions for foil layer n include at least one of x, y, and z position data associated with the required welding energy information. This is to cause the laser beam 122 from the welding laser 120 to apply the desired welding energy to the correct geographic location on the foil layer 105. It should be appreciated that the welding information may be a constant welding laser energy value, meaning that the welding laser is turned on or off, rather than modulated or changed with respect to location. The controller 150 sends control signals to the welding laser 120 to generate and provide or otherwise send the welding laser energy to the location on the foil layer 105. For example, the welding laser 120 may be controlled by the controller 150 to apply a 2 kW laser beam to the location x1 and y1 on the foil layer 105.

[0047] In some examples, the welding laser 120 is configured to have x-, y-, and / or z-axis movement capabilities, and the controller 150 sends control signals with position data to the welding laser 120 (e.g., a device or structure that moves the welding laser in at least one of these coordinates). In other examples, the build platform 130 is configured to have at least one of x-, y-, and z-directional movement capabilities such that the foil layer 105 below the welding laser 120 can be moved to a desired position to receive a predetermined welding laser energy from the welding laser beam 122. In this latter case with a moveable build platform 130, the controller 150 also sends control signals to the build platform 130 that send the build platform 130 to the correct position.

[0048] A similar process with build instructions for foil layer n is also used for the ablation energy information. Controller 150 sends control signals to ablation laser 110 to generate and deliver the desired ablation laser energy to a location on foil layer 105. Similar to welding laser 120, either ablation laser 110 or build platform 130 may include x, y, and / or z axis movement capabilities, and controller 150 sends control signals with position data to one of these devices.

[0049] FIG. 3 is a schematic diagram of an incremental build process of foil layers 105, where each foil layer 105 is added sequentially to build a 3D part. In the first diagram from the left, the process starts with a single foil layer 105. Multiple foil layers are added sequentially and stacked (i.e., moving in the direction of the right-pointing arrow as shown in FIG. 3), with each layer receiving welding and ablative laser energy to shape it into the desired layer shape. Foil layers are added until the desired 3D part 103 is formed and the process is complete. According to some embodiments, the build platform 130 can be moved (i.e., lowered) in the z-axis direction before positioning a "new" layer of foil material on the substrate.

[0050] Control of the AM system 100 is achieved using a controller 150, which in various examples is configured as a microprocessor-implemented computer system having software and hardware control modules. As shown in FIG. 1, the controller 150 may be coupled to or in communication with the welding laser 120, the ablation laser 110, the foil feed system 115, and the build platform 130, and may be coupled to motion devices for each of the lasers 110 and 120, as previously described. The controller 150 is configured with the ability to receive (e.g., stored internally or transmitted externally) build instructions, which are digital files that contain design details of the multi-layer 3D part and enable sequential build-up using welding and ablation laser processes with foil layer geometries and processing parameters.

[0051] According to at least one embodiment, laser welding is performed in the z-axis direction and laser ablation is performed in the x-axis and y-axis directions. This may be shown in the schematic diagram of FIG. 4. The welding laser 120 is configured to deliver welding laser energy in the z-axis direction via the welding laser beam 122 and, in some examples, is configured to move in the z-axis direction as shown in FIG. 4. It should be appreciated that the welding laser 120 may also be configured to move in at least one of the x-axis and y-axis directions. The ablation laser 110 is configured to deliver ablation laser energy in at least one of the x-axis and y-axis directions via the ablation laser beam 112 and, in some examples, is configured to move in the x-axis and y-axis directions as shown in FIG. 4. It should be appreciated that the ablation laser 110 may also be configured to move in the z-axis direction and, in some examples, at least one of the welding laser 120 and the ablation laser 110 may be rotated. In addition, one or both of the lasers 110 and 120 may be configured to have a scanning device as known in the art. Using lasers in the configuration described in Figure 4 has several advantages, including speeding up the process. In one embodiment, the process is speeded up due to the use of two separate lasers dedicated to each performing a different processing technique. In another example, the x and y processing with the ablation laser 110 allows the removed material to fall using gravity.

[0052] According to some embodiments, the laser welding and ablation are performed in the presence of an inert gas. For example, an atmospherically controlled build chamber 170 (see, for example, FIG. 4) may be configured to partially contain an inert gas and surround the welding and ablation laser beams 122 and 112 and the processing region 135. The inert gas may be nitrogen or argon, or any other inert gas suitable for the AM processes described herein. In some embodiments, the atmospherically controlled build chamber 170 may be an airtight chamber having a processing window (not shown) to allow at least a portion of the laser beams 112 and 122 to enter the chamber 170. The chamber 170 may be atmospherically controlled to reduce oxidation effects when performing the welding and ablation of the foil layers. A vacuum system (not shown) may be used to remove oxygen from the chamber 170, and a gas system (not shown) may supply the inert gas to the chamber 170. According to another example, an inert gas 175 may be delivered to the processing region 135 in much the same way that a shielding gas is delivered in a welding and / or ablation process, as will be appreciated by those skilled in the art. In such instances, a nozzle or other gas delivery device may be used. In either instance, the inert gas / shield gas serves to protect the surface from oxidation, particularly in instances where the foil layer material is a material that readily oxidizes in the presence of oxygen (e.g., a metal).

[0053] In some embodiments, the AM system is configured to operate continuously or quasi-continuously like a conveyor. This can be achieved in several different ways. A first example is shown in FIG. 5 and is achieved by maintaining enough material surrounding the area to be treated (the portion or area of ​​the foil layer that will undergo laser treatment) undamaged so that the roll of foil material can be advanced, as indicated by the arrow in FIG. 5. The build platform 130 (not shown in FIG. 5) can be lowered after each foil layer is laser treated. In this case, the already treated area is also lowered. The foil layer is then advanced and "covers" the already treated area. This "new" treated area is then ready to be laser treated.

[0054] A second non-limiting example of an AM system configured to operate continuously is shown in FIG. 6. A roll of foil material 107 is wound in one direction and first treated by a welding laser 120 and then treated by a second ablation laser 110 as shown. In this example, the foil layer 105 is unwound from the roll 107 and guided or otherwise fed in the direction of the black arrows as shown in FIG. 6. The foil layer 105 is exposed to welding laser energy from a welding laser beam 122 generated from the welding laser 120 and then wound into a roll and ablated by an ablation laser beam 112 generated by the ablation laser 110. As shown, the welding laser energy is delivered in the z-axis direction and the ablation laser energy is delivered in the x-axis and y-axis directions. After being ablated, the unwanted material falls (via gravity and / or pressurized gas applied to the processing area) into a waste collection device 160 where it can be reused. The treated area is then rotated back upwards again, back into the vicinity of the welding laser beam 122, and covered by a new layer of foil material from the roll 107, and the process is repeated until the 3D part is completed. In this embodiment, the "build platform" is cylindrical, and with each rotation, welding and ablation occurs, and the 3D part is built layer by layer. According to some embodiments, multiple 3D parts can be processed simultaneously using an array of welding and ablation lasers, as shown in FIG. 6. During processing, the movement of the foil layer 105 into the treatment area may be stopped or slowed down so that the foil material can be exposed to the required laser energy. In other embodiments, the foil layer 105 moves continuously.

[0055] According to some embodiments, individual sheets of foil material can be sequentially positioned on the build platform and / or substrate and processed individually.

[0056] An exemplary method 700 for additive manufacturing is described with reference to FIG. 7. First, in step 710 of method 700, a foil layer is placed in place. This is intended to position an untreated "new" layer of foil material so that it can be exposed to welding and / or ablative laser energy. In step 720, laser welding is performed on the foil layer as described above, and in step 730, laser ablation is performed on the foil layer as described above. In step 740, a decision is made, i.e., the controller 150 determines whether the 3D part is complete, i.e., whether the sequence of build instructions is complete. If the 3D part is complete, the process ends. If the 3D part is not complete, the process returns to step 710 and the next foil layer in the sequence is processed through steps 710, 720, and 730.

[0057] The aspects disclosed herein according to the present invention are not limited in their application to the details of the configuration of parts and the shapes set forth in the following description or illustrated in the accompanying drawings. These aspects may assume other embodiments and may be practiced or carried out in various ways. Examples of specific implementations are provided for illustrative purposes only and are not intended to be limiting. In particular, acts, parts, elements, and features described in connection with one or more embodiments are not intended to be excluded from a role in any other embodiment.

[0058] Additionally, the phrases and terms used herein are for purposes of description and should not be considered limiting. Any reference to examples, embodiments, parts, elements, or acts of systems and methods referred to in the singular herein may encompass the embodiments including the plural, and any reference to any embodiment, part, element, or act herein in the plural may encompass the embodiments including only the singular. References in the singular or plural do not limit the presently disclosed systems or methods, their parts, acts, or elements. The use of "including," "comprising," "having," "containing," "with," and variations thereof herein are meant to encompass the items listed thereafter and their equivalents as well as additional items. References to "or" may be construed as inclusive such that any term described using "or" refers to either one, more than one, or all of the described term. Additionally, in the event of inconsistencies in the use of terms between this document and documents incorporated by reference herein, the use of the term in the incorporated document is supportive of the use of the term in this document, and in the event of any irreconcilable discrepancy, the use of the term in this document shall control.

[0059] Although several aspects of at least one example have been described, it should be appreciated that various alternatives, modifications, and improvements will be readily contemplated by those skilled in the art. For example, the examples disclosed herein may be used in other contexts. Such alternatives, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the examples described herein. Accordingly, the above description and drawings are used by way of example only. [Explanation of symbols]

[0060] 100 AM System 103 3D parts 105 Foil layer 107 rolls 110 Ablation Laser 112 Pulsed laser beam 115 Foil Feeding System 120 Welding Laser 122 Laser beam 130 Build Platform 132 Substrate 135 Processing Area 150 Controller 160 Waste collection device 170 Atmosphere-controlled build chamber

Claims

1. 1. A method for additive manufacturing (AM) of a three-dimensional part, comprising: (a) positioning a foil layer on a substrate; (b) laser welding the foil layer to the substrate; (c) laser ablating the foil layer using a pulsed laser beam comprising light pulses having a pulse duration in the range of 0.5 ps to 10 ps inclusive to remove at least a portion of the foil layer; (d) repeating steps (a)-(c) until the three-dimensional part is completed.

2. The method of claim 1 , wherein the light pulse has a pulse energy in the range of 25 μJ to 200 μJ inclusive.

3. The method of claim 1 , wherein each pulse of the pulsed laser beam has a peak power of at least 1 MW.

4. 10. The method of claim 1, wherein laser welding is performed using a laser beam obtained from at least one of a continuous wave (CW) laser source and a quasi-continuous wave (QCW) laser source, the method further comprising providing at least one of the continuous wave (CW) laser source and the quasi-continuous wave (QCW) laser source.

5. 5. The method of claim 4, wherein at least one of the continuous wave (CW) laser source and the quasi-continuous wave (QCW) laser source is configured to have an output power of at least 1 kW.

6. 6. The method of claim 5, wherein at least one of the continuous wave (CW) laser source and the quasi-continuous wave (QCW) laser source is configured to have an output power of at least 5 kW.

7. The method of claim 1 further comprising receiving the foil layer wound as a roll of foil material.

8. 8. The method of claim 7, wherein the foil layer is at most 1 mm in thickness (inclusive).

9. The method of claim 7 , wherein the foil layer comprises a metallic material.

10. The method of claim 7 , wherein laser welding and laser ablation are performed in a treatment area, the method further comprising the steps of unrolling the foil layer in one direction from the roll and guiding the foil layer to the treatment area.

11. 10. The method of claim 1, further comprising lowering a build platform supporting the substrate prior to step (a) by moving the build platform in a z-axis direction, the z-axis direction being oriented in a plane perpendicular to the build platform.

12. The method of claim 1 , wherein the welding is performed in the z-axis direction and the laser ablation is performed in the x-axis and y-axis directions.

13. The method of claim 1 , further comprising performing the laser welding and the laser ablation in an atmospherically controlled build chamber configured to at least partially contain an inert gas.

14. The method of claim 1 , wherein the laser welding and the laser ablation are performed in a processing region, the method further comprising delivering an inert gas to the processing region.

15. 1. An additive manufacturing (AM) system for forming a three-dimensional part from a plurality of successive foil layers, comprising: a welding laser configured to generate a laser beam capable of welding a foil layer onto a substrate; an ablation laser configured to generate a pulsed laser beam capable of ablating at least a portion of the foil layer, the pulsed laser beam comprising optical pulses having a pulse duration in the range of 0.5 ps to 10 ps inclusive; A controller, The controller: receiving build instructions for each foil layer used to successively build the three-dimensional part, the build instructions including welding energy information and ablation energy information for each foil layer; an additive manufacturing (AM) system configured to send control signals to each of the welding laser and the ablation laser such that, for each foil layer, the welding laser provides a welding laser energy corresponding to the welding energy information and the ablation laser provides an ablation laser energy corresponding to the ablation energy information.

16. 16. The additive manufacturing (AM) system of claim 15, wherein the build instructions include at least one of x, y, and z position data associated with each of the welding energy information and the ablation energy information, and the controller is further configured to control at least one of a position of the welding laser and a position of the ablation laser in at least one of an x-axis direction, a y-axis direction, and a z-axis direction based on the x-axis data, the y-axis data, and the z-position data.

17. 20. The additive manufacturing (AM) system of claim 16, wherein the controller is further configured to control a foil feed system, the foil feed system configured to guide the foil layer to a processing area.

18. 20. The additive manufacturing (AM) system of claim 17, wherein the foil layer is wound as a roll of foil material, and the foil delivery system is further configured to unroll the foil layer in one direction from the roll.

19. 20. The additive manufacturing (AM) system of claim 17, wherein the welding laser is configured to weld in a z-axis direction oriented in a plane perpendicular to the processing region.

20. 20. The additive manufacturing (AM) system of claim 17, further comprising an inert gas delivered to said processing region.

21. 17. The additive manufacturing (AM) system of claim 16, wherein the ablation laser is configured to remove foil layer material in at least one of the x-axis and y-axis directions.

22. 16. The additive manufacturing (AM) system of claim 15, wherein the welding laser is configured to have an output power of at least 1 kW.

23. 23. The additive manufacturing (AM) system of claim 22, wherein the welding laser is configured to have an output power of at least 5 kW.

24. 16. The additive manufacturing (AM) system of claim 15, wherein the welding laser comprises at least one of a continuous wave (CW) laser source and a quasi-continuous wave (QCW) laser source.

25. 16. The additive manufacturing (AM) system of claim 15, wherein the ablation laser is configured such that each pulse of the pulsed laser beam has a peak power of at least 1 MW.

26. 16. The additive manufacturing (AM) system of claim 15, wherein at least one of the welding laser and the ablation laser is configured as a fiber laser.

27. 16. The additive manufacturing (AM) system of claim 15, further comprising an atmospherically controlled build chamber configured to at least partially contain an inert gas and surround the welding laser and the ablation laser.

28. 16. The additive manufacturing (AM) system of claim 15, wherein the foil layer is a metallic material having a thickness of up to 1 mm.

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