Regardless of procurement route, research shows that metal powder costs will be the biggest continuous expense through the life of an AM machine. Let’s have a look at the reasons behind the high-costs of metal powder feedstock.
Reasons for high-costs
Not the commercial priority, so far
Additive manufacturing (AM) generates an active area of materials development due to its promise to change the manufacturing game.
However, metal-based AM represents only a small fraction of AM applications. Most applications use polymers and this is where financial and commercial incentives have contributed to focus the technological and R&D efforts.
Polymers and polymer-based composites are now widely available as low-cost feedstocks. In addition, flexible AM platform is being quickly expanded and widely deployed with great success for both small and large-scale part builds, such as cars and buildings structures.
While the technical barriers for polymeric materials have been mostly overcome, additive manufacturing of metallic alloys remains challenging.
However, metal-based AM represents only a small fraction of AM applications. Most applications use polymers and this is where financial and commercial incentives have contributed to focus the technological and R&D efforts.
Polymers and polymer-based composites are now widely available as low-cost feedstocks. In addition, flexible AM platform is being quickly expanded and widely deployed with great success for both small and large-scale part builds, such as cars and buildings structures.
While the technical barriers for polymeric materials have been mostly overcome, additive manufacturing of metallic alloys remains challenging.
Technical challenges
Different requirements for different technology
One challenge for industrial powder makers desiring to serve the AM market is that there are different optimal powder size distributions for each AM process. Each method requires specific, narrow powder size distributions.
This is especially troublesome if the requested powders are of experimental alloys for which no other market exists and oversize/undersize powders might sit in inventory for years.
One challenge for industrial powder makers desiring to serve the AM market is that there are different optimal powder size distributions for each AM process. Each method requires specific, narrow powder size distributions.
This is especially troublesome if the requested powders are of experimental alloys for which no other market exists and oversize/undersize powders might sit in inventory for years.
Lack of process control and production efficiency
Most AM grade powders are produced using common atomization methods where oversize and undersize powder size fractions of each batch [21], e.g., about 80–90% for free-fall gas atomization (GA), can limit the yield of AM powder and result in increased prices to cover costs from excessive inventory.
In addition, considerable labor is involved in extensive screening of the full powder yield just to capture only a small portion (10–20%) of salable AM powders from a (typical) broad size distribution by ‘‘standard” parameters [3]. Thus, commercial powder makers often have difficulty identifying immediate economic benefit for production of special powders for AM applications and many do not have sufficient in-house process research facilities/staff/time to work on this problem.
Most AM grade powders are produced using common atomization methods where oversize and undersize powder size fractions of each batch [21], e.g., about 80–90% for free-fall gas atomization (GA), can limit the yield of AM powder and result in increased prices to cover costs from excessive inventory.
In addition, considerable labor is involved in extensive screening of the full powder yield just to capture only a small portion (10–20%) of salable AM powders from a (typical) broad size distribution by ‘‘standard” parameters [3]. Thus, commercial powder makers often have difficulty identifying immediate economic benefit for production of special powders for AM applications and many do not have sufficient in-house process research facilities/staff/time to work on this problem.
A lack of production efficiency and process control lie at the heart of gas atomized powder costs. Concentrated research is required to significantly reduce cost, expand the choice of vendors, and promote availability of experimental alloys.
Current research objectives are to:
Current research objectives are to:
- increase the yield of desired powder in each batch, primarily targeting two size ranges, 45–106 mm for EBM/PBF and 15–45 mm for DLM;
- integrate a robust process sensor (for instance an in situ particle size distribution analyser);
- develop a feedback loop with an actuation device (e.g., an automated atomization gas pressure regulator) for active in-process ‘‘fine tuning” optimisation based on the sensor feedback.
Qualification steps and warrantee
Makers of AM equipment for the PBF and DED technology increase pressure on the supply (and cost) by offering ‘‘qualified” feedstock powders. The use of these powder is limited to their own AM machines to enable operation under warrantee [2]. This type of ‘qualification’ limits the variety of powder types available from the AM system providers to a small number of common alloys.
Influence of high-costs:Limit development and testing of more exotic material compositionsSlow down adoption paceLimit range of applicationsLimit material availability
As a result of the powder size range and quality requirements, only a limited number of metal alloys have been qualified for processing by AM, significantly limiting the pace of adoption of AM techniques for a variety of metal alloy applications.
References
[1] I.E. Anderson et al., Feedstock powder processing research needs for additive manufacturing development, Curr. Opin. Solid State Mater. Sci. (2018), https://doi.org/10.1016/j.cossms.2018.01.002
[2] F. Medina, Metal Part Fabrication Using Additive Manufacturing Technologies, workshop presented at RAPID + TCT, organized by Society of Manufacturing Engineers, 2017
[3] A. Lawley, R.D. Doherty, Rapidly solidified powder processes: models and mechanisms for atomization and consolidation, in: S.K. Das, B.H. Kear, C.M. Adam (Eds.), Rapidly Solidified Crystalline Alloys, The Metallurgical Society Inc., Warrendale, PA, 1985, pp. 77–91.
[1] I.E. Anderson et al., Feedstock powder processing research needs for additive manufacturing development, Curr. Opin. Solid State Mater. Sci. (2018), https://doi.org/10.1016/j.cossms.2018.01.002
[2] F. Medina, Metal Part Fabrication Using Additive Manufacturing Technologies, workshop presented at RAPID + TCT, organized by Society of Manufacturing Engineers, 2017
[3] A. Lawley, R.D. Doherty, Rapidly solidified powder processes: models and mechanisms for atomization and consolidation, in: S.K. Das, B.H. Kear, C.M. Adam (Eds.), Rapidly Solidified Crystalline Alloys, The Metallurgical Society Inc., Warrendale, PA, 1985, pp. 77–91.