EP-4278021-B1 - METHOD OF ADDITIVE MANUFACTURING

Inventors

• STEWART, Peter Neil
• PRICE, HOWARD JAMES

Dates

Publication Date

20260513

Application Date

20220107

Claims (9)

1. A method of additive manufacturing of an article from a feed material in a chamber, the method comprising: evacuating at least some of a first gas of a set of gases from the chamber, comprising reducing a pressure therein from a first pressure to a second pressure of a set of pressures, wherein the first gas has a first concentration and a second concentration of a set of concentrations at the first pressure and the second pressure respectively; gettering at least some of the first gas from the evacuated chamber using a getter located in the evacuated chamber, thereby lowering a concentration of the first gas from the second concentration to a third concentration of the set of concentrations; and additive manufacturing the article from the feed material in the gettered chamber; the method characterised by : the gettering at least some of the first gas from the evacuated chamber comprises heating, at least in part, the getter using a fusion source; the additive manufacturing the article from the feed material in the gettered chamber comprises heating, at least in part, the feed material using the fusion source; and wherein the getter is a substrate comprising a base plate for additive manufacturing the article thereon.
2. The method according to claim 1, wherein heating, at least in part, the getter comprises melting, ablating and/or subliming at least in part, the getter.
3. The method according to any previous claim, wherein the getter is a Ti alloy, a Ni alloy, an Al alloy, a Co alloy or a stainless steel.
4. The method according to any previous claim, wherein gettering at least some of the first gas from the evacuated chamber using the getter comprises reducing the pressure therein from the second pressure to a third pressure of the set of pressures, wherein the first gas has the third concentration at the third pressure.
5. The method according to any previous claim, wherein the first gas is oxygen and the third concentration is in a range from 0 ppm to 50 ppm.
6. The method according to any previous claim, comprising backfilling or purging the evacuated chamber before gettering at least some of the first gas from the evacuated chamber using the getter.
7. The method according to any previous claim, comprising measuring the third concentration.
8. The method according to any previous claim, comprising introducing the feed material into the chamber after gettering at least some of the first gas from the evacuated chamber using the getter.
9. The method according to any previous claim, wherein the feed material comprises a first row transition metal, a second row transition metal, a group III element, and/or a mixture thereof.

Description

FIELD OF THE INVENTION The present invention relates to additive manufacturing, for example powder bed fusion. BACKGROUND TO THE INVENTION Additive manufacturing (AM), also known as three-dimensional (3D) printing, generally refers to processes used to create articles or objects from layers of material sequentially formed under computer control. Additive manufacturing provides creation of articles having complex shapes, geometries or structures, including internal voids, that may not readily be formed according to conventional subtractive manufacturing processes, such as machining, or conventional casting or moulding processes. Materials suitable for additive manufacturing include metals, ceramics, glasses and polymers. ISO/ASTM52900-15 defines seven categories of additive manufacturing processes, including powder bed fusion (PBF). Particularly, PBF techniques, such as direct metal laser sintering (DLMS), selective heat sintering (SHS), selective laser sintering (SLS), selective laser melting (SLM), laser metal deposition (LMD) and electron beam melting (EBM), are suitable for creation of metal articles, from feed materials such as metal powders and/or filaments. Similarly, polymeric articles may be manufactured from feed materials such as powders and/or filaments comprising polymeric compositions, including thermoplastics. The feed materials are heated to elevated temperatures, for example at a temperature T in a range of about 23Tm≤T≤Tm, where Tm is the melting temperature of the feed material. At such temperatures, the feed material may react with reactive gases, such as O2, forming products such as oxides. In addition or alternatively, residual gases may be incorporated into the articles as impurities. These impurities may be deleterious to the properties (e.g. mechanical properties) of the articles when included therein. Hence, powder bed fusion is typically conducted in a protective atmosphere, for example in an inert atmosphere such as an Ar and/or a N2 atmosphere, and also in an enclosed chamber having such an atmosphere. However, residual and/or reactive gases may remain and/or be present in the protective atmosphere, for example at 10s ppm to 100s ppm levels, and are thus still deleterious to the properties of the articles thus formed. Furthermore, unused feed material, such as unsintered or unfused feed material (for example which is next to the used feed material), is also heated to relatively elevated temperatures, at which the feed material may still react with and/or incorporate such gases. Thus, reuse or recycling of unused feed material may be precluded due to contamination and/or effects due to thermal cycling in these PBF techniques, while disposal of such waste feed materials may be environmentally hazardous. Hence, there is a need to improve additive manufacturing, for example powder bed fusion. US 2018/304540 A1 describes a system and method for controlling three-dimensional printing using measured processing effects. SUMMARY OF THE INVENTION It is one aim of the present invention, amongst others, to provide a method of additive manufacturing which at least partially obviates or mitigates at least some of the disadvantages of the prior art, whether identified herein or elsewhere. For instance, it is an aim of embodiments of the invention to provide a method of additive manufacturing that reduces levels of residual and/or reactive gases, thereby lessening deleterious effects arising therefrom on articles formed by additive manufactured and/or on unused feed material. The invention provides a method of additive manufacturing of an article from a feed material in a chamber, the method comprising: evacuating at least some of a first gas of a set of gases from the chamber, comprising reducing a pressure therein from a first pressure to a second pressure of a set of pressures, wherein the first gas has a first concentration and a second concentration of a set of concentrations at the first pressure and the second pressure respectively;gettering at least some of the first gas from the evacuated chamber using a getter located in the evacuated chamber, thereby lowering a concentration of the first gas from the second concentration to a third concentration of the set of concentrations; andadditive manufacturing the article from the feed material in the gettered chamber. The gettering at least some of the first gas from the evacuated chamber comprises heating, at least in part, the getter using a fusion source, the additive manufacturing the article from the feed material in the gettered chamber comprises heating, at least in part, the feed material using the fusion source; and the getter is a substrate comprising a base plate for additive manufacturing the article thereon. A second aspect, not claimed, provides a method of additive manufacturing, for example by and/or comprising powder bed fusion, of an article from a feed material, for example comprising a powder and/or a filament, in a chamber