Metal Powder Feedstock Recycling and Sampling Strategies

Objective:

Help AM users select the optimum recycling strategy for their AM process and end-use application, to minimise material waste and cost, and understand how to implement this strategy in their organization.

Problem:

• Roughly 5-20% of the feedstock used in powder bed AM machines is turned into the final part, while the remaining powder material needs to be recycled, to ensure that the business case remains viable.
• At present, AM users are using a wide range of strategies to recycle, re-use, and revert powder feedstock in powder bed AM. These strategies have been developed on a case-by-case basis, and with no real consensus gained on what is considered best practice for recycling AM feedstock powders.
• One of the key challenges that needs to be overcome is understanding what are the key process variables influencing the powder quality, and how to measure and track these during powder recycling and re-use.
• There is also a need to couple the defined recycling and reuse strategies with a standardized nomenclature system, and define a standardized sampling strategy to ensure that powder quality is maintained.
• Additionally, there is a need for AM users to understand when a powder batch has reached the end of its useful life, and in what scenarios a powder batch should be quarantined or conditioned.

Impact:

• This project will address: ‘Gap PC7: Recycle & Re-use of Materials’ and ‘Gap PM5: Metal Powder Feedstock Sampling’.

Solution:

• This project will evaluate the advantages, disadvantages, and suitability of current recycling and sampling practices for metal powders, collating information from the industry, published literature, and existing standards. Standard definitions and best practice recommendations on how to implement recycling strategies will be developed, outlining key process variables and powder quality parameters that should be controlled during recycling and re-use.
• This project will also provide information on sampling strategies for the defined recycling strategies. Sampling strategies are required to ensure that the recycling process can be monitored for quality control and to support traceability. The project will consider the sampling practices defined in ASTM B215 and provide recommendations on how to collect representative samples; it will also outline best practices that powder producers and AM users can use to maintain powder quality. 

Output:

• Guidance on metal powder recycling and re-use in additive manufacturing
• Guidance on sampling strategies for metal powders during recycling and re-use in additive manufacturing

 

Figure 1: Typical workflow for metal powder re-use in powder bed fusion