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

Abstract

PurposeThere is a requirement to match selective laser melting (SLM) technologies to a wider range of polymeric materials, as 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, this paper aims to explore the potential use of PP materials of varying molecular weight (Mw).Design/methodology/approachPP polymers of differing Mw were characterised using a range of analytical techniques, including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), rotational rheometry and real-time hot-stage (optical) microscopy.FindingsThe techniques are sufficiently sensitive to distinguish Mw 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 all grades of PP, including higher Mw grades, which potentially offer improved mechanical performance.Research limitations/implicationsThe range of techniques (DSC, oxidative induction time and TGA) form an effective analytical package with which to consider new polymeric materials for SLM.Practical implicationsHigh-Mw PP polymers, in tape or powder form, have potential use in SLM processes, providing scope to enhance part properties in future.Originality/valueThis is believed to be the first in-depth study noting the influence of PP Mw on important physical performance in a proprietary SLM process, using holographic beam manipulation.