A team of researchers at Missouri University of Science and Technology, Missouri, USA, is collaborating with Honeywell Federal Manufacturing & Technologies, Kansas City, Missouri, on a five-year project to perform material analysis for the selective laser melting process in a metal powder bed. Dr Ming Leu, Keith and Pat Bailey Missouri Distinguished Professor of Integrated Product Manufacturing and the Director of the Intelligent Systems Center at Missouri S&T, is leading a team of seven Missouri S&T professors on the project.
With equipment Honeywell purchased and installed in Toomey Hall for the $5 million project, Leu and colleagues have four research objectives: to predict the properties of the built parts, control microstructures to achieve desired properties, maximise powder reuse, and increase product sustainability.
The project consists of five tasks: powder characterisation, material property characterisation methods, temperature effects on material properties, controlling microstructure and mechanical properties and chemistry specifically for Additive Manufacturing. Stainless steel 304L is used initially as the build material.
“We look at how process parameters affect the mechanical properties of the manufactured part and how to control those parameters to achieve desired properties,” stated Leu. “The laser’s power, the beam diameter, the traverse speed, the line spacing and the layer thickness all can affect the parts produced.” Chemical composition and environment temperature are other factors that can significantly affect the part’s properties, he says.
The team is also investigating ways to reuse powder to reduce the cost of raw materials. A problem with this, Leu says, is that due to heat effect the powder immediately surrounding the part made may have degraded or clumped to be used again to make parts as good as those from virgin materials. Reduced strength is an example of how the reused powder might negatively affect the finished product.