Assessing the influence of non-uniform gas speed on the melt pool depth in laser powder bed fusion additive manufacturing.

Purpose: This paper aims to investigate the influence of non-uniform gas speed across the build area on the melt pool depth during laser powder bed fusion. The study focuses on whether a non-uniform gas speed is a source of process variation within an individual build.

Design/methodology/approach: Parts with many single-track laser scans were printed and characterized in different locations across the build area coupled with corresponding gas speed profile measurements. Cross-sectional melt pool depth, width, and area are compared against build location/gas speed profiles, scan direction, and laser scan speed.

Findings: The study shows that the melt pool depth of single-track laser scans produced on parts are highly variable. Despite this, trends were found showing a reduction in melt pool depth for slow laser scan speeds on the build platform near the inlet nozzle and when the laser scans are parallel to the gas flow direction.

Originality/value: A unique dataset of single-track laser scan cross-sectional melt pool measurements and gas speed measurements was generated to assess process variation associated with non-uniform gas speed. Additionally, a novel sample design was used to increase the number of single-track tests per part, which is widely applicable to studying process variation across the build area.