The Inflation and it’s Stability in the Thermoforming Process

The production process Thermoforming is normally used to produce different kinds of packing in plastic. The final stage in this process is the inflation of a flat (and thin) plate down into the wall of a mould. This creates the final shape of the product. The inflation is performed applying a gas pressure on the top of the plate, which press the plastic cylinder down. This kind of process delivers products with considerable difference in the distribution of the thickness. During the inflation in Thermoforming the plastic may burst. The occurrence of this burst, or break, puts a limit on the possibility to produce a specified product at some, or all, processing conditions. Hence, here the purpose is to investigate and understand both how the thickness distribution varies on the final product as a result of the inflation and the mechanism leading to the burst. In the beginning the focus will be on the burst or break, using both experiments and numerical calculations to understand the phenomena.