Quantifying Accuracy of Metal Additive Processes Through a Standardized Test Artifact

Two limitations of AM processes when compared to CNC subtractive processes are reduced dimensional accuracy and rougher surface finish. Accuracy and surface finish of metal additive processes, such as DMLS or SLM, are generally much looser than precision turning or grinding processes. Because of this, it is important to have an understanding of an AM machine’s capabilities—the designer must be satisfied with the tolerances and finishes possible, or additional post-processing must be added. One way to examine the capabilities of an AM process is by printing and measuring test artifacts. This paper examines a test artifact proposed by NIST that is intended to demonstrate many different capabilities and types of accuracy. Three identical builds are printed on a Concept Laser metal additive machine and measured. The capabilities of the machine are quantified and discussed, along with additional recommendations for improving the test structure design and the measurement process.