Method for producing at least one part from precious metal and / or biocompatible material

Abstract

Method for producing at least one dental prosthesis part (5) from a biocompatible, first material by means of layered construction by laser metal fusion, comprising the following method steps: (a) applying a powder layer (2) of the first material to a substrate plate (1) made of a non-biocompatible, second material and then selectively laser melting that region of the applied powder layer (2) which corresponds to the respective layer geometry of the at least one dental prosthesis part (5), (b) applying a further powder layer (2) of the first material and then selectively laser melting that region of the applied powder layer (2) which corresponds to the respective layer geometry of the at least one dental prosthesis part (5), (c) repeating step (b) until the at least one dental prosthesis part (5) is made of the first material, and (d) machining, in particular milling, an upper side (5a) facing away from the substrate plate (1) and an underside (5b) facing the substrate plate (1) of the at least one dental prosthesis part (5) in a machining machine tool (6), in particular a milling machine, in a single clamping operation, wherein before machining the underside (5b) one or more non-load-bearing regions (9) of the substrate plate (1) are cut free by machining and wherein the underside (5b) is machined through a previously machined region (9) of the substrate plate (1).

Description

[0001] The invention relates to a method for producing at least one dental prosthesis from a biocompatible, first material by means of layered construction using laser metal fusion. Biocompatible materials are materials that are medically approved, particularly for implants, preferably in accordance with DIN EN ISO 10993 or the European Medical Device Regulation. These can be, for example, metal powders with the following composition, although the method is not limited thereto: Ni61, 4Cr22, 9Mo8, 8Nb3, 9Fe2, 5Mn0.4Ti0.1, Ti6Al4V (e.g., Ti6Al4V ELI (Grade 23 according to ASTM)), CoCr (in particular according to ASTM).

[0002] It is known from the prior art to produce dental prostheses using the Laser Metal Fusion (LMF) process - often also referred to as Selective Laser Melting (SLM). In the LMF process, the material to be processed is applied in powder form in a thin layer to a substrate plate. The powdered material is completely melted locally using laser radiation and, after solidification, forms a solid layer of material. The substrate plate is then lowered by the amount of one layer thickness and more powder is applied. This cycle is repeated until all layers of a dental prosthesis have been remelted. The finished dental prosthesis is cleaned of excess powder and then subjected to post-processing, such as milling, for example to smooth the surface of the dental prosthesis, rework functional surfaces or create functional holes.

[0003] Such manufacturing processes using biocompatible material have become known, for example, through EP 1 021 997 A2, EP 1 974 688 A1 and WO 2010 / 003 882 A2.

[0004] EP 1 021 997 A2 describes the production of dental prostheses from biocompatible material using laser sintering processes.

[0005] EP 1 974 688 A1 discloses the layered construction of a frame, one or more dental prosthetics arranged therein, and several lateral bars that attach the dental prosthetics to the frame, using the LMF process from a biocompatible material. Referencing on the frame or bars serves to subsequently rework the dental prosthetics by milling. Since the production of the frame and bars consumes a large amount of the expensive biocompatible material, this known manufacturing process is associated with relatively high costs.

[0006] WO 2010 / 003 882 A2 discloses the production of a dental prosthesis by building up a partial volume of the dental prosthesis from biocompatible material powder using the LMF process on a substrate plate (milling plate) made of the biocompatible material. The remaining partial volume of the dental prosthesis is then milled out of the substrate plate in a milling machine. A reference mark on the substrate plate serves to position the substrate plate and clamp it in the milling machine. Because the substrate plate is made of biocompatible material, this known manufacturing process is also associated with relatively high costs and takes a comparatively long time due to the milling out of the substrate plate.

[0007] DE 10 2016 204 462 A1 also discloses that, in the production of a component, a raw component is first additively manufactured on a carrier plate. Subsequently, at least a section of the carrier plate is clamped in a processing machine. The processing machine performs a separating machining step on the raw component. The raw component is then separated from the carrier plate. A carrier plate can be used for this purpose, which has a plurality of carrier plate sections, each supporting at least one component to be additively manufactured. The carrier plate sections are detachably connected to one another.

[0008] DE 10 2008 031 925 A1 discloses a method for manufacturing products by means of at least partial layered construction, in particular by selective laser melting, comprising the steps: (a) providing a base plate, (b) applying a layer of a curable material, (c) selectively curing predetermined regions of the applied layer based on geometric data of the product, (d) repeating steps (b) and (c) until the geometry of a first partial volume of the product has been created as cured material, (e) removing the uncured material. Furthermore, a reference marking is provided, the unit formed from the base plate and first volume regions is clamped and positioned using the reference marking, and the second partial volume of the respective product is released from the base plate.

[0009] DE 10 2012 108 217 A1 discloses a method for producing a molded part, which is manufactured using freeform technology based on digitized data and subsequently post-processed in a processing device using the digitized data. In this method, a fixing structure extending from the molded part is produced simultaneously with the molded part, and the molded part is fixed in the processing device using the fixing structure and then post-processed.

[0010] In contrast, the present invention has the object of providing a more cost-effective LMF process for producing parts, in particular from precious metal and / or biocompatible material.

[0011] This object is achieved according to the invention by a method for producing at least one dental prosthesis from a biocompatible, first material by means of layered construction by laser metal fusion, with the following method steps: (a) applying a powder layer of the first material to a substrate plate made of a non-biocompatible, second material and then selectively laser melting that area of the applied powder layer which corresponds to the respective layer geometry of the at least one dental prosthesis part, (b) applying a further powder layer of the first material and then selectively laser melting that region of the applied powder layer which corresponds to the respective layer geometry of the at least one dental prosthesis part, (c) repeating step (b) until the at least one dental prosthesis is made from the first material, and (d) machining, in particular milling, an upper side facing away from the substrate plate and an underside facing the substrate plate of the at least one dental prosthesis part in a machining machine tool, in particular milling machine, in a single clamping, wherein before machining the underside one or more non-load-bearing regions of the substrate plate are freed by machining and wherein the underside is remachined through a previously machined region of the substrate plate.

[0012] According to the invention, one or more dental prosthetic parts are constructed on a substrate plate made of the second material, which allows the use of a substrate plate made of a more cost-effective material, in particular of a non-precious metal and / or of a material that is not medically approved, e.g., for implants, and therefore non-biocompatible. The non-biocompatible material can, for example, be a metal with the following composition, without the method being limited to this: stainless steel, structural steel, etc. The substrate plate is preferably a thin standard plate that is built up with parts as completely as possible. Such substrate plates can be produced in large numbers using laser cutting systems or punching systems.

[0013] According to the invention, in method step (d) the upper side facing away from the substrate plate and the underside facing the substrate plate of the at least one dental prosthesis part are reworked in a single clamping operation, so that a high level of accuracy is achieved. In addition, in method step (d) one or more non-load-bearing areas of the substrate plate are cut out by machining. This allows the underside of the at least one dental prosthesis part to be advantageously reworked through a previously machined area of the substrate plate. Since the rework is carried out on both sides in a single clamping operation, there can be no undesired offset between the rework from above and below. The substrate plate has a load-bearing function (analogous to the lateral webs of EP 1 974 688 A1) until the dental prosthesis parts have been milled out and, for example, fall downwards into a collecting container.

[0014] After the LMF process, the substrate plate is clamped in the milling machine, in which the unit formed by the substrate plate and the at least one dental prosthesis part is preferably mounted so that it can rotate, in particular by approximately 180°, in order to first rework the top side and, after a 180° rotation, also the bottom side, without having to re-clamp. Machining in a single clamping operation can be achieved, for example, using a rotary axis of the milling machine clamping device or using a clamped rotating device for the substrate plate.

[0015] In particular, if a support structure, which supports the at least one dental prosthesis part on the substrate plate, has been built up layer by layer from the first material in process steps (a) to (c), parts of the support structure are destroyed by machining in process step (d). The remaining parts of the support structure must be sufficiently stable to withstand the (low) post-processing forces.

[0016] Preferably, in process steps (a) to (c), at least one reference mark (e.g., pins or similar) is also created on the substrate plate for post-processing in the machine tool. The reference mark serves to calibrate the substrate plate in the machine tool. Alternatively, existing mechanical interfaces on the substrate plate can also be used as reference marks.

[0017] Further advantages and advantageous embodiments of the subject matter of the invention will become apparent from the description, the claims, and the drawings. Likewise, the features mentioned above and those listed below can be used individually or in combination in any desired manner. The embodiments shown and described are not to be understood as an exhaustive list, but rather are exemplary in nature for describing the invention.

[0018] They show: Fig. 1a to 1d show the process steps of the method according to the invention for producing dental prostheses from biocompatible material by means of layer-by-layer construction by laser metal fusion.

[0019] In Fig. 1a, a powder layer 2 made of biocompatible material is applied to a substrate plate (sacrificial plate) 1 made of non-biocompatible material. Subsequently, the region 3 of the applied powder layer 2 corresponding to the respective layer geometry of the dental prosthesis to be manufactured is selectively remelted using a laser beam 4 (process step (a)). This region 3 forms a solid material layer after solidification.

[0020] A further powder layer 2 of the biocompatible material is applied to this laser-melted, solid powder layer and then the area 3 of the applied powder layer 2 which corresponds to the respective layer geometry of the dental prosthesis to be produced is selectively melted by means of the laser beam 4 (process step (b)).

[0021] In process step (c), process step (b) is repeated until the dental prosthesis part 5 is produced from the laser-melted, biocompatible material ( Fig. 1b).

[0022] The finished dental prosthesis part 5 is cleaned of excess powder and then, in a process step (d), subjected to a machining finish in a machine tool 6, e.g., a milling machine, in order to smooth the surface of the dental prosthesis part 5, to rework functional surfaces, or to create functional bores, etc. After the substrate plate 1 has been clamped in a holder 7 of the machine tool 6 that can be rotated, e.g., by 180°, the upper side 5a of the dental prosthesis part 5 facing away from the substrate plate 1 is first reworked using a milling tool 8 of the milling machine 6 ( Fig. 1c). Subsequently, the substrate plate 1 is rotated by approximately 180° and then the underside 5b of the dental prosthesis part 5 facing the substrate plate 1 is reworked using the milling tool 8, in that the milling tool 8 first mills away one or more non-load-bearing areas 9 of the substrate plate 1 and then the dental prosthesis part 5 is reworked through these areas 9 ( Fig. 1d). Since the post-processing of both sides 5a, 5b of the dental prosthesis part 5 is performed in a single setup, no undesirable post-processing offset between the two sides 5a, 5b can occur, and a high level of machining accuracy is achieved. By milling away non-load-bearing areas 9, up to and including the complete destruction of the substrate plate 1, the substrate plate 1 becomes a sacrificial part.

[0023] As in the Fig. 1a and Fig. As shown in Figure 1b, in process steps (a) to (c), a support structure 10, which supports the dental prosthesis part 5 on the substrate plate 1, is also constructed layer by layer from the biocompatible material in parallel with the dental prosthesis part 5. This support structure 10 is then partially or completely destroyed in process step (d) using the milling tool 8. The substrate plate 1 and the support structure 10 continue to have a supporting function until the dental prosthesis parts 5 are milled out and fall downwards into a collecting container.

[0024] As in Fig. 1c and Fig.1d, in process steps (a) to (c) a reference marking (e.g. a pin) 11 is also created on the substrate plate 1 for post-processing in the milling machine 6. This reference marking 11 serves to calibrate the substrate plate 1 and the dental prosthesis part 5 built thereon in the milling machine 6. Alternatively, a hole or similar on the substrate plate 1 can also be used as a reference marking, provided that the dental prosthesis part 5 to be built can be positioned with sufficient repeatability relative to the substrate plate 1.

[0025] Instead of a dental prosthesis made from a biocompatible workpiece, a piece of jewelry 5 (e.g., watch parts) made from expensive precious metal can also be manufactured on a substrate plate 1 made from a non-precious metal. Corresponding gold or platinum substrate plates would be very expensive.

Claims

[1] Method for producing at least one dental prosthesis part (5) from a biocompatible, first material by means of layered construction by laser metal fusion, comprising the following method steps: (a) applying a powder layer (2) of the first material to a substrate plate (1) made of a non-biocompatible, second material and then selectively laser melting that region of the applied powder layer (2) which corresponds to the respective layer geometry of the at least one dental prosthesis part (5), (b) applying a further powder layer (2) of the first material and then selectively laser melting that region of the applied powder layer (2) which corresponds to the respective layer geometry of the at least one dental prosthesis part (5), (c) repeating step (b) until the at least one dental prosthesis part (5) is made of the first material, and (d) machining, in particular milling, an upper side (5a) facing away from the substrate plate (1) and an underside (5b) facing the substrate plate (1) of the at least one dental prosthesis part (5) in a machining machine tool (6), in particular a milling machine, in a single clamping operation, wherein before machining the underside (5b) one or more non-load-bearing regions (9) of the substrate plate (1) are cut free by machining and wherein the underside (5b) is machined through a previously machined region (9) of the substrate plate (1). [2] Method according to claim 1, characterized by that the unit formed from the substrate plate (1) and the at least one dental prosthesis part (5) is mounted in the machine tool (6) so as to be rotatable, in particular by approximately 180°. [3] Method according to one of the preceding claims, characterized bythat in the process steps (a) to (c) on the substrate plate (1) a support structure (10), which supports the at least one dental prosthesis part (5) on the substrate plate (1), is also built up layer by layer from the first material. [4] Method according to claim 3, characterized by that in process step (d) parts of the support structure (10) are destroyed by machining. [5] Method according to one of the preceding claims, characterized by that in the process steps (a) to (c) at least one reference marking (11) is also built up on the substrate plate (1) for the post-processing in the machine tool (6). [6] Method according to one of the preceding claims, characterized by that existing structures on the substrate plate (1) are used as reference markings.

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