Polymers for SLS

by Manfred Schmida, Antonio Amadoa and Konrad Wegener. Department of Mechanical and Process Engineering, Swiss Institute of Technology8008 Zürich, Switzerland

Selective Laser Sintering (SLS) is close to be accepted as a production technique (Additive Manufacturing). However, one problem limiting employment of SLS for additive manufacturing in a wide-ranging industrial scope is thenarrow variety of applicable polymers. The commonly applied SLS powder to date is polyamide 12 (PA 12). PA 12 or ccompounds of PA 12 (dry blends) are approximately 90 % of complete industrial consumption. The remaining smallquantity is distributed on polyamide 11 (PA11) and some other ‘exotic’ polymers (TPU, PEBA, P(E)EK). Industry is awaiting commodity polymers like polypropylene (PP) or polyethylene (PE) crucial to open new market segments. But several approaches launching those polymers failed. But what are the reasons for the difficulties in developing new SLS powders? The contribution is to answer this and highlights the combination of intrinsic and extrinsic polymer properties necessary to generate a polymer powder promising for SLS application. Particle shape, powder distribution, thermal, rheological and optical requirements must be considered and only a particularly controlled property combination leads to successful SLS implementation. Thermal behavior, particle shape and –distribution is discussed in detail, although the other properties can’t be disregarded for providing new commercially successful SLS powder finally.

Keywords: Additive Manufacturing, Selective Laser Sintering, Polymer powders, 3D-Printing

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