Laser Beam Melting of Complexly Shaped Honeycomb Structures

Abstract

Laser beam melting (LBM) offers the opportunity to manufacture highly complex structures and geometries and thus provides a big potential to produce lightweight parts. In previous research projects, a software tool has been developed that achieves the placement of hexagonal honeycombs (of any size and wall thickness) on free formed surfaces in a load-oriented manner and thus offers entirely new possibilities for designing lightweight components in CAD (e.g. [1–2]).

This work examines the production of metal hexagonal honeycombs from the material AlSi10Mg with the LBM-process. By adapting the exposure and process parameters, it was possible to manufacture overhanging structures with an overhang angel < 30° (relative to build platform) without support structures, while still achieving an acceptable surface roughness (in the context of this study: Ra = 45 µm). Conventional complex and time consuming post-processing steps can thus be avoided and a higher utilization of building space can be achieved. Furthermore, since the critical size for a lightweight structure is the minimum possible density, it was investigated to which minimum values the wall thicknesses of the hexagonal structures can be reduced using LBM. Apart from that, the stability of the manufactured honeycombs was analyzed in as-built condition and heat treated by pressure test and related to the honeycomb density. This has been used to compare additively manufactured honeycombs with conventionally manufactured ones.