This study describes the influence of polymer flow length on mechanical properties of tested polymer, specifically polycarbonate. The flow length was examined in a spiral shaped mould. The mould cavity’s surface was machined by several methods, which led to differing roughness of the surface. The cavity was finished by milling, grinding and polishing. In order to thoroughly understand the influence of the mould surface quality on the flow length, varying processing parameters, specifically the pressure, were used. The polymer part was divided into several segments, in which the micro-mechanical properties, such as hardness and indentation modulus were measured. The results of this study provide interesting data concerning the flow length, which was up to 3% longer for rougher surfaces, but shorter in cavities with polished surface. These results are in disagreement with the commonly practiced theory, which states that better surface quality leads to greater flow length. Furthermore, evaluation of the micro-mechanical properties measured along the flow path demonstrated significant variance in researched properties, which increased by 35% (indentation hardness) and 86% by indentation modulus) in latter segments of the spiral in comparison with the gate.
Fused Filament Fabrication (FFF) printers are usually designed to create a product with one single material. Some of them allow fabricating items in multiple colours but creating a single product consisting of two different materials remains an advantage of industrial 3D printers only. The aim of this research was to develop a design of a device with two printheads which enables to print products with two different materials, compatible with a cheap and commonly available FFF device Prusa i3MK2S, and the subsequent production of a prototype. A key aspect of the design was the hardware compatibility of the device with the given printer while maintaining the maximum possible printing area. Dual extrusionMulti-material 3D print FFF printer
Injection molding is an advantageous technology for the mass production of plastic parts without the necessity for additional procedures. The applicability of this method is still partially limited by the required properties of the manufactured parts. Especially in the field of optics, there is a need to produce thick-walled parts while maintaining their transparency. This paper reports on how various shapes of gating systems affected the process parameters and cavity filling during the injection molding of polycarbonate thick-walled specimens. These outcomes demonstrated that film gates and their alternatives are more suitable for the standard injection molding of thick-walled optical products than the triple-edge gating systems. Favorable results were observed particularly in the uniformity of cavity filling, size of shrinkage, and in the occurrence of defects such as voids or sink marks.
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