Additive Manufacturing of Polypropylene: A Screening Design of Experiment Using Laser-Based Powder Bed Fusion.

Iñigo Flores Ituarte,Olli Wiikinkoski,Anton Jansson

doi:10.3390/polym10121293

Iñigo Flores Ituarte, Olli Wiikinkoski + Show 1 more

Open Access

https://doi.org/10.3390/polym10121293

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Journal: Polymers	Publication Date: Nov 22, 2018
Citations: 34	License type: CC BY 4.0

Affiliation: Aalborg University, Aalto University, Örebro University

Abstract

The use of commodity polymers such as polypropylene (PP) is key to open new market segments and applications for the additive manufacturing industry. Technologies such as powder-bed fusion (PBF) can process PP powder; however, much is still to learn concerning process parameters for reliable manufacturing. This study focusses in the process–property relationships of PP using laser-based PBF. The research presents an overview of the intrinsic and the extrinsic characteristic of a commercial PP powder as well as fabrication of tensile specimens with varying process parameters to characterize tensile, elongation at break, and porosity properties. The impact of key process parameters, such as power and scanning speed, are systematically modified in a controlled design of experiment. The results were compared to the existing body of knowledge; the outcome is to present a process window and optimal process parameters for industrial use of PP. The computer tomography data revealed a highly porous structure inside specimens ranging between 8.46% and 10.08%, with porosity concentrated in the interlayer planes in the build direction. The results of the design of experiment for this commercial material show a narrow window of 0.122 ≥ Ev ≥ 0.138 J/mm3 led to increased mechanical properties while maintaining geometrical stability.

Highlights

Additive manufacturing (AM) of thermoplastic polymers using powder-bed fusion (PBF) has become an alternative to conventional manufacturing methods [1]
We found that higher Ev values caused warping, curling, and geometrical distortion, thereby preventing the production of usable specimens within the required geometrical tolerance level according to the ASTM
This study shows that commercially available PP is an alternative material in PBF, the mechanical properties are inferior to parts made by conventional methods, such as injection molding or other PBF friendly polyamides, such as polyamide 12 (PA12)

Summary

Introduction

Additive manufacturing (AM) of thermoplastic polymers using powder-bed fusion (PBF) has become an alternative to conventional manufacturing methods [1]. Equipment manufacturers integrate AM systems to their manufacturing processes [2] as PBF technology offers many advantages, for the production of geometrically complex components in low- to mid-volume batches [3,4]. Technological projections consider AM an important element of future digitalization of manufacturing [5]. The adoption of AM contributes to reducing the upfront cost linked to conventional manufacturing, simultaneously improving flexibility in manufacturing new products [7]. A paradigm change involves mass-production needing to become highly flexible to answer individualized needs in a resource-friendly manner [8]

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