Optimization for surface finish of parts manufactured by polymer laser powder bed fusion

Description

Laser powder bed fusion (L-PBF) for polymers is one of the many additive manufacturing technologies that has since many years been associated with rapid prototyping. It can produce parts with complex geometrical shapes that are not possible in injection moulding (IM). However, the final part qualities such as surface roughness, mechanical performance, and dimensional accuracy are not comparable to what can be achieved by IM. As the name suggests, L-PBF final part quality has a significant reliance on the ‘laser’, hence this research was carried out to investigate the dependence of surface finish on laser scanning process parameters and then optimize for it. Studies show that laser scan spacing, laser scan speed, and laser power, which directly influence the consolidation energy input into the powder, are primary contributors to surface finish quality [1]-[2]. A two-level full factorial design of experiments (DOE) built around the process parameters of laser power, laser scan spacing, laser speed, and number of contour layers (upskin, downskin, and side) was used to manufacture the parts, i.e. 2^4. The parts were characterized for surface finish using a focus variation microscope after being post-processing by pressurised media blasting. There are trends of a direct correlation between roughness reduction increase in consolidation energy input but at high energy consolidation input significant loss of final part micro-feature resolution is observed. However, results indicate that the surface finish depends mainly upon the laser process parameters of the contours (upskin, downskin, and side). Based on the results from the DOE the surface finish can be improved by optimizing process parameter values corresponding to a reduction in surface roughness parameter, Sq (root mean square height) values of the final part. The values can be reduced by at least 5% overall and up to 30% on selected faces. Further work needs to be carried out to find a process parameter span in the relatively higher consolidation energy zone within which parts with reduced roughness can be obtained without compromising micro-feature resolution.

Period	2024
Event title	24th International Conference on Metrology and Properties of Surfaces
Event type	Conference
Conference number	24
Location	Marrakech, MoroccoShow on map
Degree of Recognition	International