The Plastics Manufacturing Process is a complex business. Here we have put together an explanation about some of the processes we use at Adreco.Injection Moulding is a process of shaping plastic by melting it and injecting it into a predesigned mould. It offers many advantages to alternative plastic manufacturing methods, including minimal losses from scrap (since scrap pieces can be melted and recycled), and minimal finishing requirements. The process uses large Injection Moulding machines, which advance the resins through six major processes to produce everything from intricate computer parts to plastic widgets. Although Injection Moulding machines are a complex piece of equipment, they consists of two basic elements: the injection unit and the clamping unit.
The process starts with a mould or tool, which is clamped under high pressure to accommodate the injection and cooling process.
Then, pelletized resins are fed into the machine, followed by the appropriate colorants or additives. Adreco accurately dose these additives to ensure consistency and efficiency. The resins then fall into an injection barrel, where they are heated to a melting point, and then injected under pressure into the mould/tool through a screw.
The molten plastics are then “held” or contained within the tool, and hydraulic or mechanical pressure is applied to make sure all of the cavities within the tool are filled. The plastics are then allowed to cool within the mould, typically using water circuits that are integrated within the tool itself (much like a car radiator) to cool the temperature of the tool cavities. The tool is then opened by separating the two halves of the mould.In the final step, the plastic part is ejected from the tool with ejecting pins. The completed part may contain extraneous bits called runners or sprues, which can be trimmed off and recycled. The entire process is cyclical, with cycle times ranging from a few seconds to a few minutes for the largest of parts.The injection moulding process requires some complex calculations. Every different type of resin has a unique shrinkage value that must be factored in to the tooling design. Adreco understand the importance of matching the right polymer to the right component and then designing the right tool for the purpose.