Investigation of an incremental dual Laser Powder Bed Fusion strategy for improving the quality of up-facing inclined surfaces

Abstract

Additive manufacturing can generate parts with complex shapes such as industrial mould components. However, the resulting surface texture often does not fulfil the industrial requirements, thus requiring costly post-processing. This paper further develops a dual laser Powder Bed Fusion technique for in-situ improving the quality of inclined surfaces. It combines selective powder removal by laser-induced shock waves and subsequent laser remelting. This method is applied to a novel tool steel (M789) suitable for mould applications with the objective of up-scaling to steeper and larger surfaces. In the first step a design of experiments focused on the laser remelting process was carried out. In the second step the dual laser processing was applied at defined height steps during building, investigating the effect on the surface texture for inclinations up to 60°. Finally, aforementioned strategies were applied to manufacture a real mould component with significantly improved as-produced surface quality. Consequently, the traditionally required post-processing steps can be considerably reduced.