Have you ever wondered what work goes into producing every day plastic items such as your car dash board, bottle lids, electronic housings for power tools, remote controls and the humble washing up bowl? Injection moulding is the process used to produce these and many other high volume identical items and components. In its simplest form a mould, also known as a tool, is created for the plastic, resin or polymer to be injected into and then allowed to cool, in order to release the part. But how can we be sure the process will work and more importantly, flow in the mould, as it should?
Injection moulding sounds straightforward doesn’t it, but there is in fact a lot of science involved. For example, expensive mistakes can occur if the design of the tool which produces the mould isn’t effective and requires adapting, especially if it is made from steel. Even after accruing more years than I care to count, working in this field, gaining vital expertise, technical errors can happen to the best tool designers, especially when dealing with complicated shapes. It is therefore generally accepted a good idea to implement mould flow analysis before any tool is made.
Mould flow analysis provides us engineers with a simulation of how the plastic should behave when injected into the mould and actually predicts how it will flow through the mould. Thus providing us with a pretty good idea of how it will actually perform during the production process. The analysis helps to spot any defects or problems prior to developing the mould tool. It provides informed answers to questions with regards to any unforeseen issues such as air traps and pockets, the position of the gates in the mould, or sparking a conversation about whether the molten material needs changing. All this aids the crucial design process.
Of course this analysis adds additional upfront development costs with respect to the time and effort that's required, but costs and effort that are generally considered as essential and worth it as a best way to avoid some potentially disastrous unexpected results. Other materials can also be moulded, such as rubber and metal (MIM/PIM), depending on the properties required to fulfil the end task. But getting back to the manufacturing demands put upon plastic, there is no change, with the overarching goal to "let it flow".
