Manufacturing researchers at the National Institute of Standards and Technology (NIST) have identified important challenges for powder bed fusion, the chief method for "printing" metal parts. By identifying the factors that influence the manufacturing process, professionals will improve the creation of 3D-printed parts like medical implants.
A new NIST report presents an integrated view that systematically links process inputs to in-process phenomena that might either be measured or modeled. The researchers also connected inputs to the ultimate determinants of part quality, such as material characteristics, dimensional accuracy, and surface roughness.
Powder bed fusion usually employs a laser to selectively heat, melt, and fuse the thin top layer of metal particles on a bed of powder. Once a layer is completed, more powder is spread on top and the process is repeated until accumulated layers comprise the designed part.
The additive manufacturing process, however, often creates system performance and reliability issues that can undermine part quality: dimensional and form errors, unwanted voids in the fused layers, and high residual stress in the final parts.
To address the problems, the NIST researchers developed a detailed understanding of the many intricacies of powder bed fusion. The team distilled a detailed breakout consisting of 12 categories of "process parameters," 15 types of "process signatures," and six "product qualities." Cause-and-effect relationships were charted among variables in each of the three categories.
"This cause-and-effect breakout can guide research to develop measurement and sensing capabilities as well as modeling and simulation tools—all with the aim of enabling better process control," said NIST mechanical engineer Brandon Lane, one of the report's authors.
