MM SCIENCE JOURNAL I 2022 I MARCH 5575 COMPUTER ANALYSIS OF THE TECHNOLOGICAL PROCESS OF A SELECTED COMPONENT'S PLASTIC INJECTION PETR BARON, MAREK KOCISKO, EDUARD FRANAS Technical University of Kosice, Faculty of Manufacturing Technologies with seat in Presov, Slovak Republic DOI: 10.17973/MMSJ.2022_03_2022004 e-mail to corresponding author: petr.baron@tuke.sk The article describes an optimization methods analysis in the technological process of plastic injection using the simulation tool Autodesk Moldflow Adviser. The Polyethylene 120J was the material used in production of the plastic part analyzed. Following the simulations, deficiencies affecting the quality of the final part were identified. Modifications were gradually made both in the cover's design and as changes in the process parameters so as to eliminate the deficiencies identified. In the first step, the value of the injection time was modified based on the results of the analysis of the determination of the ratio of solidified layers at the end of the process of filling the mold cavity. The second type of adjustment required a change in the molding's design. Based on the result of the simulation of forecasting cooling quality, we proposed a change in the wall thickness of selected model elements, specifically the adjustment of the wall thickness of the bolted joint column from 3 to 4 mm. The last adjustment consisted of adjusting the additional pressure profile. KEYWORDS computer simulation, plastic injection, polymer, quality prediction. 1 INTRODUCTION Plastic and rubber products have become an integral part of our lives. However, activities in industrial production, too, need to comply with environmental protection. It is increasingly necessary to implement steps related to separation and recycling of plastic waste, especially in the area of consumer goods. In addition to the problems associated with processing of large plastic waste, plastics may release very small particles - the so-called microplastics. The plastic monomers then enter the drinking water, oceans and animal bodies. A pressing problem to be addressed technologically by the current and the next generation is the elimination of excess plastic waste. Nevertheless, plastics and their composites have an irreplaceable role, for example in car construction [Panda 2019, Petruska 2020]. These materials are increasingly replacing traditional materials in car construction. This is mainly due to their good mechanical and physical properties. They achieve higher strength, thermal and chemical resistance, resistance to UV radiation, etc. The use of such materials also reduces the vehicle weight, which is reflected, among other things, in lower fuel consumption. Plastics used in the vehicle interior muffle noise and vibration. Polymeric materials represent the most important of all materials in terms of production volume and consumption. In competition with conventional materials, especially metals, polymers have largely prevailed due to their ease of processing, low density, and generally beneficial utility-to- price ratio. Much less energy and labor is expended on the production and processing of plastics than on metal processing. Many plastics also have a higher resistance to chemicals than metals [Rusinko 2021]. Thermoplastics and thermoplastic elastomers are most often processed by extrusion (production of semi-finished products) and injection molding (production of final products). Thermosets and non-thermoplastic elastomers are processed by compression molding or by injection molding [Dillinger 2019, Pollak 2019]. One of the oldest plastics processing technologies is pressing. In this technology, the molten material is not moved over a greater distance, so no fluidity is required of it. The advantage of this kind of processing is the operation cycle speed and high production efficiency. This plastic processing technology uses lower pressures. Another plastic processing technology is blow molding. In this case, a plastically moldable blank is inserted into a hollow mold. After the mold is closed, the blank is pressed from the inside onto the mold walls cooled with compressed air. In the next step, the divided mold is opened and the finished product is ejected. The whole procedure is repeated [Dillinger 2019, Pollak 2019]. The most commonly used plastic processing technology is injection molding. The polymer melt is injected under pressure into the mold cavity of the injection mold. The product acquires the shape of the cavity. In the curable resin injection, it is the curing that takes place in the mold, or vulcanization if the material injected is natural rubber. This technology makes it possible to economically produce high-quality products of sufficient precision from a wide portfolio of plastic materials. Typical for injection-molded products is very good dimensional and shape accuracy. The process is automatic. The use of the material is wide-ranging, close to 100%. Recently, the processing of polymeric materials by additive production technologies has become popular. FFF/FDM (Fused Filament Fabrication/Fused Deposition Modeling) technologies represent the most widespread technology in the field. Its principle is based on extruding the molten polymer through a nozzle and this material is then deposited in subsequent layers [Monkova 2020, Dobransky 2021]. 2 COMPUTER SIMULATION OF PLASTIC INJECTION TECHNOLOGY Manufacturing process simulation is an important tool for securing concurrent or parallel engineering goals. One of the main goals is to detect defects in the production process in a timely manner, which can take place concurrently with planning, tooling and so on. In the case of plastic injection technology, a number of tools from the CA (Computer Aided) systems portfolio can be applied, which enables engineers and developers to identify bottlenecks and potential errors in the process of final product design. It is a so-called pre-production analysis capable of detecting potential manufacturing problems such as cold joints, welds, air pockets, as well as optimal inlet placement, optimal settings of technology parameters, and the like. The type of material used, the technological parameters and the design of the mold, as well as the choice of suitable technological equipment, have a significant impact on the mechanical and physical properties of the finished part. The overall properties of the ejected plastic part in terms of material selection are affected by the following parameters [Dobransky 2009]: