Injection moulding is the most common method used to create large numbers of identical items from plastics. Most polymers can be used in the process and products produced by injection moulding include bottle lids, plastic combs, small pieces of furniture and even car door panels. Essentially, the injection moulding process involves feeding plastic polymers in a pelletized form through a hopper into a chamber.
As the material passes along the chamber a rotating screw mixes and melts the material. Once sufficient molten plastic material has collected at the end of the chamber the screw acts as a plunger and the material is injected into a mould, usually made of metal. Moulds are carefully designed to reflect the exact requirements of the product being produced. Finally, the plastic solidifies into a shape that has conformed to the shape of the mould. Once cooled slightly, sometimes a robotic arm is used to remove the moulded components but it is more common for the freshly-made items to drop out of the mould into a chute leading to a collection container.
An injection moulding machine is used to manufacture plastic products by the injection moulding process detailed above. There are two main parts to the machines – the injection unit and the clamping unit. In the majority of injection moulding machines the mould is fastened in the horizontal position but moulds can also be fitted in the vertical position in some cases allowing gravity to aid the process. Moulds are most commonly fastened to the machine by manual clamps using bolts but can also be fastened using hydraulic or magnetic clamps which both allow for faster tool changes.
Injection moulding machines are rated by tonnage and Shot weight which expresses the amount of clamping force that the machine can exert to keep the mould closed during the process and the maximum weight of article that can be moulded. However, machines are primarily classified by the type of driving systems they use namely hydraulic, mechanical, and electrical or hybrid. Hydraulic machines are most predominant in most parts of the world with the exception of Japan and were the only option available until 1983. Although widely-used they tend not to be as precise as other machine types. Mechanical injection moulding machines tend to be more reliable than other types.
Electric injection moulding machines decrease operating costs by reducing energy consumption and also address some of the environmental concerns around these machines. They are more expensive than other types but are quieter, faster and more accurate. Hybrid machines combine the best of hydraulic and electric types but in reality use almost the same amount of electricity to operate as a standard hydraulic machine.
There are many manufacturers/suppliers of injection moulding machines and new advances are being made in the field all the time and so it is worth researching options and services on offer before making a final decision.
Multiplas Enginery Co., Ltd. is the company of specializing in producing injection moulding machine, rubber moulding machine, high speed injection molding machine and so on machinery. Learn more information about injection moulding machines, please feel free to contact with Multiplas.
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