Influence of Layer Time on the Mechanical Properties of Thin-walled Parts Produced from Modified Polycarbonate Reinforced with Caron Fibres by a Pellet Extrusion Modelling (PEM) Process

Abstract

Large-format additive manufacturing is a production technology that enables production of large-scale parts made from fibre-filled thermoplastic pellets. A kinematic structure, such a robot or a CNC portal machine, carries the extruder that plasticizes polymer granulates and extrudes material layer by layer (Pellet Extrusion Modelling - PEM). The technology is usually used in tooling manufacturing processes. One specific application of PEM technology is production of thin-walled lightweight structures using modified polycarbonate reinforced with carbon fibres. Thin-walled parts are used as a core in production of structural composite parts. The critical process parameter of PEM is layer time. It is a key technical parameter that affects the temperature of the bonding of two layers, which relates to the mechanical properties of the printed part. Ensuring the correct process window of a temperature during the bonding process is thus critical. For structural components where mechanical properties are inspected, the correct layer time must be chosen. This paper focuses on a study of temperatures during the bonding process of a structural thin-walled part printed via PEM technology. The layer temperatures during the cooling process before application of the next layer were investigated. The layer time was changed to monitor the thermal influence of this parameter. The specimens were prepared and the mechanical tests were carried out to present the effect of the layer time on the mechanical properties of the thin-walled 3D printed parts.