METAL 3D PRINTING SPREAD POWDER DENSITY SENSOR
Metal 3D printing powder density changes during manipulation. It is important to precisely know the density of layers of powder as they are spread in a build chamber of a powder bed printer, from which the laser sintered or otherwise bonded parts are produced. One method of determining density of the powder is by using the equation density = mass/volume. We built a custom balance scale apparatus to obtain precise values for this equation.
How Does It Work?
We establish the volume by controlling the layer thickness to +- several microns over 100 micron thick layers using a precision linear actuator in a precision machined build cylinder. We weight each layer of recoater blade spread powder by weighing the entire build chamber on an ultra low friction counterbalanced pivot scale, using a 0.1 mg resolution load cell for weight measurements.
The proof of concept apparatus we designed, built and tested verified our approach to obtaining highly precise density measurements for each layer spread in a metal powder bed 3D printing process. This information can help characterize powder density just before sintering or bonding in the 3D powder bed printer part building process, leading to greater understanding of final part attributes earlier in the process. The apparatus we designed and verified in a proof-of-concept development project is a promising base for development of a prototype commercial test machine, the next stage in the development towards commercialization. Completion of the next stage, prototype development, will lead to equipment that researchers can begin to use for studying spread powder densities.
Proof of Concept
Government of Canada / National Research Council of Canada, winner [link]