The importance of powder and defining adequate powder KPVs
Complex applications requirements and lack of standardised powder specifications
In addition, not all metal powders are equal in terms of their fundamental properties even when manufactured via the same technique. Even when chemically equivalent, the properties of metal powders vary widely depending on both the production method used and the manufacturing process conditions.
The production of AM metal powder generally consists of three major stages :
Atomisation has generally been identified as the best way to form metal powders for AM due to the geometrical properties of the powder it yields.
- Rapid prototyping;
- Technology used:
- Powder-bed – laser-based or e-beam-based
- Cold spray
- Direct energy deposition (laser or e-beam)
- Traceability requirements
- Batch size
- Powder properties and level of control required over these properties
- Availability of chemical composition
- Delivery time and reliability
- directly from the AM machine provider;
- from third party companies, who offer ‘validated’ powders.
- directly from an atomisation company.
‘Validated powder’ defines feedstock suitable for use in AM. Whilst validated powder can de-risk procuring powders it does limit users to a single source supplier and inhibits the development of in-house expertise.
In a production environment, AM parts are required to achieve the highest quality. In this case, validated powder or powder sourced from the AM machine supplier is likely to be the best option. More often than not, the machine manufacturer will also support the customer if there are any build issues. However, for applications requiring complete control and traceability of the powder, this procurement route may show a lack of transparency.
In research-based environments, considerations are different. For prototyping or technology development the end-user is likely to require additional control and understanding over the powder properties, attempt processing new exotic materials or experiment with machine parameters. In this scenario, sourcing material directly from the powder manufacturer may be best suited.
Unfortunately, there is no one-size-fits-all answer for procurement routes. The first step is a careful understanding of powder feedstock impact on processing to define suitable KPVs and production routes. As for procurement routes, the type of applications and end-use of the AM system need to be considered and leveraged carefully.
 ‘Wohlers Report 2014: 3D Printing and Additive Manufacturing State of the Industry Annual Worldwide Progress Report’, Wohlers Associates, Inc, Fort Collins, Colorado, USA, 2014
 J. Dawes, R. Bowerman and R. Trepleton, Introduction to the Additive Manufacturing Powder Metallurgy Supply Chain, Johnson Matthey Technol. Rev., 2015, 59, (3), 243–256