Shrinkage and Warpage in Polymer Injection Moulding: Models and Simulation

Today the world is moving towards zero waste, sustainability and circular economy. Plastic waste is a critical issue tackled on a global scale. It is everybodys responsibility to help contribute to this ever raging issue. Injection moulding is the most widely used technique for the production of parts made out of polymers. Although very versatile there are various shortcomings to this process which need to be worked upon to get an optimized process. Two of the most common and critical defects of this process are shrinkage and warpage, which require a trial and error methods to reach the most optimum process settings. This means investing a lot of capital, labour, time, material, energy and efforts. While optimizing the process, there is plenty of waste generated along the process. This calls for a dire need of finding a solution that reduces not only efforts and resources being utilized but also reduces the usage of energy being put in and the waste generated thereby. The aim of this thesis is to assess and analyse the efficiency of the simulations, to find out how close or how accurate a simulation study could be in order to reduce utilization of resources, increase efficiency and reduce wastage by getting a particular process setting right. In this study, first a practical experiment on the machine was made, to have observations of the behaviour of the parts; after which the exact same parameters from the practical inputs and outputs were used for simulations. This gives us a comparable data. The materials used were all unfilled PP, ABS and PA 6 with a simple plate geometry with a sprue gate in a single cavity cold runner mould. Each material was processed at their respective process parameters, and six samples were produced for measurement. A filling and gate freezing study was carried out before setting the process. As expected it was observed that the semi crystalline materials - PP and PA shrink more than the amorphous material ABS. The results obtained by the simulation were very comparable to the experimental results and were about 70% accurate. Experimental shrinkage values were in the range of 0.750.9% for ABS, 1.51.7% for PP and 1.51.8% for PA; whereas, the results predicted by the simulation were 0.6% for ABS, 1.41.5% for PP and 1.21.5% for PA.submitted by Er. Devavnshi KapadiaUniversität Linz, Masterarbeit, 2019(VLID)459085