Selective laser melting using holographic beam manipulation: influence of polypropylene molecular weight

2017-03-02T13:51:48Z (GMT) by Barry Haworth John Tyrer Zhou Zhou
Purpose – There is a requirement to match selective laser melting (SLM) technologies to a wider range of polymeric materials, since the existing market for SLM powders is dominated by polyamide PA12. Drivers include the tailoring of physical properties to individual applications, or cost reduction. Polypropylene (PP) currently has limited use in SLM, so the potential use of PP materials of varying molecular weight (Mw) is explored here. Design / methodology / approach – PP polymers of differing molecular weight were characterised using a range of analytical techniques, including DSC, thermogravimetric analysis (TGA), rotational rheometry and real-time hot-stage (optical) microscopy. Findings – The techniques are sufficiently sensitive to distinguish molecular weight effects, notably in terms of material viscosity. The stable sintering region for SLM has been defined clearly. Some success was achieved in melting parts using some grades of PP, including higher molecular weight grades, which potentially offer improved mechanical performance. Research limitations / implications – The range of techniques (DSC, OIT and TGA) form an effective analytical package with which to consider new polymeric materials for SLM. Practical implications – High-MW PP polymers, in tape or powder form, have potential use in SLM processes, providing scope to enhance part properties in future. Originality / value - This is believed to be the first in-depth study noting the influence of PP molecular weight on important physical performance in a proprietary SLM process, using holographic beam manipulation (HBM).