Plastic manufacturing

The plastics industry has a long and complex supply chain stretching from the producers of plastics raw materials and additives to the end-user (customer industries). Different product groups, for example automotive components and retail packaging, have markedly different supply chains. Different sources of organic renewable resins as well as composites and technical additives are being developed as a response to the market demands of environmentally friendly, mechanically performing and cheap plastic products.

The sector is extremely wide,covering raw material production of hundreds of different natural and synthetic resins, product design for a wide variety of different sectors and product manufacturing using tens of different technologies. In this scenario simulation and mathematical modelling play a relevant role. It helps designers understand their product’s mechanical and thermal performance early in the design stage, saving lots of time and money otherwise spent in expensive dies and moulds. It also helps manufacturers in their attempt to optimise their processes in aspects such as mould flow filling, heating and cooling process efficiencies and quality of the finished part.

Thermoplastic and thermosetting plastics differ completely not only in their chemical structure, but also in the way they are manufactured and the applications they are used for.

Common thermoplastic manufacturing techniques include injection moulding, extrusion, blow moulding, rotomoulding, machining or combinations of two or more of those technologies. All of them rely on thermal processes to melt the plastic and cool it down and also geometrical and mechanical restrictions to give the finished part the desired shape. Some of them also include the use of specific additives, pressurized gases or liquids as well as non-conventional sources of energy such as electromagnetic induction and ultrasounds. Simulation provides extremely valuable information to better understand these processes, where and how they may fail and also optimise them in terms of cycle time and energy consumption.

For thermosetting plastics, most common manufacturing techniques are injection and reaction injection moulding, compression moulding, pultrusion and resin transfer moulding. Processes differ from thermoplastic manufacturing insofar some thermosets are liquid at room temperature, other need two phases (catalyst and resin) to be mixed in the moulds or require higher pressures and temperatures to be cured. CFD models of mould flow filling, FEA or CFD thermal models of the curing processes and mechanical performance of the moulds under high pressure conditions are just some of the most typical simulations.

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