WEB Towards component series production in laser powder bed fusion by melt pool controlWednesday (01.01.2020) 00:00 - 00:15 Part of:
Laser powder bed fusion has evolved from rapid prototyping towards a rapid manufacturing technology enabling highly individualized and complex components. The process parameters i.e. laser power, scan speed, laser beam diameter, hatch distance significantly affect both productivity and quality of the fabricated component. For instance, a study by Metelkova et al. shows, that altering the laser beam diameter can increase volume build rates by 840 %. In addition, precisions in the micrometer range can be obtained making costly post-processing obsolete. The aforementioned process parameters determine the melt pool behavior, which in turn define the resulting properties of the component. Melt pool control and physical characteristic process maps revealing these correlations are thus crucial for process driven laser powder bed fusion. The industrial potential given by melt pool control is rarely applied due to the absence of such physical process maps correlating melt pool behavior with resulting properties, such as porosity or mechanical performance.
In this contribution dimensionless numbers are derived employing dimensional analysis, which physically correlate the melt pool geometry with both process parameters and material properties. The extensive experimental data collected for the commercially available powders AlSi10Mg, 1.4404 (316L), 2.4856 (IN625), Ti6Al4V, 1.2709 (MS1) and AlMgSc (Scalmalloy®) indicates, that a material independent scaling law has been found to predict the melt pool geometry reliably. These results are used to fabricate customized lattice structures with low particle adhesion. The influence of process parameters on the relative and material density and mechanical properties of lattice structures as well as its predictability by energy based closed-form analytical models is then assessed taking into account the part position on the build plate. The presented research brings the potential to foster economic and competitive component series production with laser powder bed fusion.
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