Wear protection in the plasticizing unit of thermoplastic injection moulding machines is challenging, due to ever-accelerating development of plastics and the further development of injection moulding technologies. In order to develop economical and tailor-made solutions for the use of special materials, used in plasticizing units and tools, the superimposed wear mechanisms must be considered separately. In the present work, the individual wear zones are treated separately and adjusted with practical model tests and calculation tools. The plastic is considered in every state of aggregate phase in which it is also relevant for wear protection (solid and liquid). In the future, the developed plastic pin-on-disk test enables an adjustment and investigation of the so-called "hedgehog effect" ("Igeleffekt") on various steels and coatings. With the new test, it was possible to generate wear on tool surfaces and to detect the transfer filler particles into the wear track. A further point was the evaluation of wear in small wear gaps under high injection speeds and the effect on wear resistance of high-alloyed materials. Due to the so far too small considered dissipation of the passing, high glass fibre reinforced plastic melt, the increase in temperature led to a massive decrease in steel hardness. This could also be proven with the help of 3D-injection moulding simulations. In the area of the non-return valve, the complex melt flow between two differently fast moving walls could be realized with the help of a newly developed calculation model. With the help of this self-programmed tool, it is possible to mathematically verify the dissipated energy and to present pressure, temperature and viscosity distributions as numerical values and also graphically. In addition, an economical wear protection concept has been developed for the non-return valve, in order to achieve maximum protection against abrasive wear on the flights while at the same time ensuring good corrosion resistance with a tailor-made composite material solution. This concept is an elegant, flexible and long-term economic solution, which has properties adapted to the load collective in each area and thus ensures efficient protection for use in the plasticizing unit. For a comprehensive understanding of the different wear mechanisms of the investigated and verified model tests, in future wear models would have to be developed that take into account the movements of the individual particles and its mechanical energy through the contact with the steel surface in this tribological system "plastic melt/filler particles/ tool wall).
|Translated title of the contribution||Wear models and wear protection in the plasticizing unit of thermoplastic injection molding machines|
|Publication status||Published - 2018|
Bibliographical noteembargoed until 02-10-2023
- wear protection
- wear model
- check valve
- plasticizing unit