INFLUENCE OF HEAT TREATMENT AND DIFFERENT CUTTING CONDITIONS ON THE MACHINABILITY IN ADDITIVE-SUBTRACTIVE PROCESSING

Abstract

For many applications, the surface quality, geometric accuracy and stress state of parts produced using laser-based powder bed fusion (PBF-LB) are insufficient. A stress relief and machining as post-processing operations allow to overcome these issues. PBF-LB materials have a unique microstructure. Their machinability therefore differs from that of cast or wrought materials. The microstructure can be altered by a stress relief heat treatment, which can change the machinability further. In this paper, the machinability of AlSi10Mg parts in the as-built condition and stress relieved condition is examined when wet and dry peripheral milling with cutting speeds up to 1,000 m/min. The PBF-LB parts were manufactured in different build-up directions. The stress relief decreased the material microhardness by approximately 16 %. This lower microhardness did not significantly affect the process forces but influenced the surface characteristics. The best surface quality was achieved when milling with the highest considered cutting speed of 1,000 m/min and when using metalworking fluids. Particularly the number of surface defects such as the smearing of material could thus be reduced. For the as-built conditions, good surface qualities can be achieved in dry cutting with high cutting speeds.