ADDITIVE LAYER MANUFACTURING

Abstract

A method for the manufacture of a component of defined geometry from two or more materials using a powder bed ALM process includes providing a bed of a first powdered material, selectively fusing portions of the first powdered material to build up a first three dimensional portion of the component geometry and fusing a powder containment bund from the first material to contain unfused first powdered material. A bed of a second powdered material is deposited onto the powder containment bund and selectively fused to build up a second three dimensional portion of the component geometry. Unfused first powdered material can subsequently be removed from a first side of the bund and unfused second powder from a second side of the bund. Remaining parts of the bund which do not form part of the defined geometry of the component can be removed to provide the net shape component.

Claims

1. A method for the manufacture of a component of defined geometry from two or more materials using a powder bed ALM process, the method comprising; providing a bed of a first powdered material, selectively fusing portions of the first powdered material to build up a first three dimensional portion of the component geometry, fusing a powder containment bund from the first material whereby to contain unfused first powdered material, providing a bed of a second powdered material onto the powder containment bund and selectively fusing portions of the second powdered material to build up a second three dimensional portion of the component geometry, removing unfused first powdered material from a first side of the containment bund and removing unfused second powder from a second side of the containment bund, and subsequently removing parts of the containment bund which do not form part of the defined geometry of the component.

2. A method as claimed in claim 1 wherein the containment bund comprises a single separating wall extending across a top layer of fused first powdered material.

3. A method as claimed in claim 2 wherein the containment bund further comprises one or more perimeter walls integrally formed with the separating wall.

4. A method as claimed in claim 3 wherein the perimeter wall or walls extend orthogonally with respect to the separating wall.

5. A method as claimed in claim 4 comprising a perimeter wall formed from fused first powdered material.

6. A method as claimed in 3 comprising a perimeter wall formed from fused second powdered material.

7. A method as claimed in claim 3 wherein the or each perimeter wall is arranged with respect to the separating wall to provide one or more containment vessels, the containment vessels each containing just one of the first and second powdered materials.

8. A method as claimed in claim 7 wherein one containment vessel is nested inside another.

9. A method as claimed in claim 7 wherein two containment vessels share a separating wall and perimeter walls extend from opposite sides of the separating wall.

10. A method as claimed in claim 1 wherein the bed of first powdered material is laid on a base plate of an ALM apparatus.

11. A method as claimed in claim 1 wherein the bed of first powdered material is laid on; an already existing containment bund separating wall, or a support structure built for the component, or an already built portion of the component.

Description

BRIEF DESCRIPTION OF FIGURES

[0015] Embodiments of the invention will now be further described with reference to the accompanying Figures in which;

[0016] FIG. 1 is a schematic showing apparatus for a powder bed ALM process and a component being formed therein as is known from the prior art;

[0017] FIG. 2 shows a first step in accordance with a method of the invention;

[0018] FIG. 3 shows a second step in accordance with a method of the invention;

[0019] FIG. 4 shows a third step in accordance with a method of the invention;

[0020] FIG. 5 shows a fourth step in accordance with a method of the invention;

[0021] FIG. 6 shows end products manufactured according to the method of FIGS. 2, 3, 4 and 5.

DETAILED DESCRIPTION OF FIGURES AND EMBODIMENTS

[0022] As shown in FIG. 1, a powder bed 1 is raised into the path of a spreading device 2 which spreads a thin layer of powder across a base-plate 3. The base-plate typically comprises a tool steel. Selected regions of the powder corresponding to a shape which it is intended to build are fused together (and also to the base-plate) by heat from a laser 4. The laser 4 is arranged to scan in two dimensions within a plane parallel to that in which the base plate extends. The base-plate 3 is gradually lowered with respect to the laser 4 during the process enabling layer upon layer of powder to be applied and sintered by the laser resulting in a three-dimensional build. This layering process can create one or more components 5 simultaneously. Unfused powder 5a remains on the base plate around the component 5.

[0023] In methods in accordance with the invention, a bund wall may be built in parallel with the base plate 3 enclosing the unfused powder 5a. The material of the powder 1 can then be changed to a second powder and the bed of second powder laid onto the bund wall.

[0024] FIG. 2 shows a first step in a method in accordance with the invention. A bed of a first powder 21 is deposited on a base plate 20 of an ALM apparatus. A defined component geometry 22 is gradually built by selectively fusing regions of the powder bed. In addition, a bund is formed to contain the unfused powder 21. The bund shown is made up from a separating wall 23 and a perimeter wall 24. The perimeter wall may comprise any convenient shape and is optional. The component geometry 22 is integrally formed with the bund separating wall 23.

[0025] FIG. 3 shows a subsequent step of a method in accordance with the invention which follows the step of FIG. 2. As can be seen in FIG. 3, a bed of a second powder 31 is deposited on top of the separating wall 23. The defined component geometry 22 is gradually added to by selectively fusing regions of the second powder bed resulting in component geometry portions 32 which are integrally formed with the component geometry portions 22. Additionally, a second perimeter wall 34 is formed to contain the unfused second powder 31.

[0026] Once build of the component geometry has been completed, unfused second powder 31 can be removed from a bund defined by the separating wall 23 and perimeter wall 34. For example, a pump could be used to suck out the unfused second powder 31. Alternatively, the base plate 20 on which the build stands could be upturned allowing the unfused second powder 31 to be poured out. The result of this step is shown in FIG. 4.

[0027] Once the unfused second powder 31 has been removed for recycling, the base plate 20 can be removed allowing the unfused first powder 21 to be removed for recycling. The result of this step is shown in FIG. 5. As can be seen, this comprises integrally formed bund walls 23, 24 and 34 and two material component geometries 22, 32. All parts of the bund wall 23 which do not also form part of the component geometry 22 are then removed. The result of this step is shown in FIG. 6. As can be seen, all that remains is component geometry 42.