A residual heat compensation based scan strategy for powder bed fusion additive manufacturing
Ho Yeung, Brandon M. Lane
Typical scan strategies for laser powder bed fusion (LPBF) additive manufacturing systems apply a constant laser power and scan speed while scanning the laser back and forth in a 'hatch' pattern to cover geometric areas on each powder layer. Localized preheating from adjacent scan paths and heat accumulation in corners or narrow geometries result in inconsistent melt-pool morphology and temperature history within a layer. A new control approach is proposed which compensates the residual heat through laser power adjustment. A model called residual heat factor (RHF) is developed based on temporal and spatial history of the scan to 'quantify' the residual heat effect, and laser power is controlled proportional to this RHF. Experiments are conducted on a custom-controlled LPBF testbed on Nickel-alloy (IN625) bare plate, and the effects of this unique scan strategy are investigated by in-situ melt-pool monitoring in combination with post-process part quality measurements.