Have you ever wondered how plastic components, combs, toothbrushes and bottle caps are made? They are obviously made by plastic, through a special process called the injection moulding. The term may be unfamiliar to most of us, but this technology has helped in improving our lives by creating components that are difficult to be created by our hands.
Plastic can be reshaped when it is heated. By injecting melted plastic granules into a mould, it creates a new component. The process is now widely used in large factories, mainly to manufacture parts for products. It saves up labor costs, minimizes errors that can be done by men, and is able to produce the same parts over a short time. It is good for mass production, but to some smaller corporations, injection moulding is very costly because it requires huge investments on moulding machines.
In this process, plastic granules are poured into the hopper that looks like a large funnel. The granules will go through a reciprocating screw and then heated in the barrel at various melting points from 248 to 509 degrees Fahrenheit, depending on the material. The heated granules are then passed to the nozzle, and pumped through the mould cavity into the mould. Pressure is put on the mould to make sure that the materials hold in shape of the mould. Next, the component is allowed to cool down, and the time depends on the thickest part of the component, but it usually takes only a few seconds. After the component has fully cooled down, it is ejected and the process starts all over again to produce the same parts.
The moulds used by these moulding machines are designed by engineers, and later on made by mould-makers out of steel and aluminum to increase the durability of the moulds.
The common products made by injection moulding are milk cartons, bottles and small electrical components. Again, with this marvelous technology, we save up a lot of labor – after all, people do get bored of doing redundant chores over and over again, but machines don’t!