Functionality test of metal powder in additive manufacturing

Purpose

The properties of metal powders intended for powder bed-based additive manufacturing are critical to how well the process function as well as final material quality. A number of these powder properties have an effect on the flowability of the powder. It is not possible to determine whether a powder has acceptable flowability for the current process / machine brand only by standard powder characterization. RISE therefore offers practical functionality testing of metal powder with relevance to flowability and packing properties with the intention of providing information on how the current powder works in the process.

This service can advantageously be combined with Powder characterization for additive manufacturing to provide a deeper understanding of the result.

Method

The test is performed in two steps using different methodology and with different focus, which also gives the opportunity to interrupt the experiment after the first stage if the result is clearly negative.

Step 1: The powder spreading properties are examined with an equipment (TESTER) that mimics the process used in laser powder bed fusion technology. A number of layers are spread over an area of ​​125x125 mm with a rubber or steel blade attached to an experimental recoater. Recoater speed and layer thickness are varied and the outcome in terms of packing density is defined. Topographic studies of the top layer can be performed with confocal microscopy where varied focus is used for imaging with great depth of field for calculation of various parameters that describe the surface characteristics.

Step 2: The powder spreading properties are then examined directly in the intended powder bed machine. The equipment is filled with the powder and a number of layers are spread over the substrate plate via the powder spreading unit (recoater) in the machine. The powder layer is studied with raking light and documented. This procedure is repeated for a number of lowering of the substrate plate and a number of spread powder layers. An approved result is a homogeneous, evenly distributed, and repeatable powder spread. The results are linked to results from the TESTER equipment and previous experience at RISE to provide an overall assessment of the powder functionality.

This service can advantageously be combined with the services Printing with Laser Powder Bed Fusion for metallic materials or Parametric development for laser powder bed fusion.

Deliveries

The results are delivered according to agreement, usually in the form of a written report which can be supplemented  with an oral presentation including PowerPoint. The customer is provided with a statement on the powder's functionality in the process.

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