No abstract

No abstract

No abstract

In contrary to the traditional injection molding process, the selective laser sintering process offers a nearly unlimited freedom of design. However, the dimensional accuracy of an SLS part is significantly influenced by the process, the material and its design. In order to achieve high accuracy, the parts need to be repositioned, parameters readjusted and parts consistently rebuilt in an iterative process. In industry this process leads to enormous consumption of process time and polymer powder.Increased dimensional inaccuracy is often caused by the accumulation of polymer melt and the resulting shrinkage effects. Thus, highly accurate SLS parts can be manufactured using three dimensional, filigree structures in order to replace volumetric part sections. In this paper, the potential of using 3D-structures, for enhancing SLS parts’ accuracy is shown. Thus, influencing parameters, such as positioning, scale, process time and geometry feature are systematically varied. Additionally the effect of adjacently positioned parts influencing the dimensional accuracy shall be investigated.

Abstract The additive manufacturing process of the laser sintering of polymers (LS) allows the production of complex parts right from CAD data. However, the manufactured parts often show dimensional inaccuracies. In order to fundamentally determine the influencing parameters on the accuracy of LS parts, a hatching specimen, a layer-specimen and defined part geometries are manufactured and subsequently measured. These, combined with a theoretical observation of the layer wise geometry buildup, are used to determine the fundamental portions of the development of dimensions in building direction (z-direction). The results indicated a defined powder adhesion height at the top and the bottom of a melted layer, along with the dependency of melt depth and the hatch number for small structures. Depending on the nominal heights of an LS part, either an oversize or undersize was detected.