The Injection molding
Injection molding is principally used for the production of the thermoplastic parts, although some progress has been made in developing a method for injection molding some thermosetting materials. The problem of injecting a melted plastic into a mold cavity from a reservoir of melted material has been extremely difficult to solve for thermosetting plastics which cure and harden under such conditions within a few minutes. The principle of injection molding is quite similar to that of die-casting. The process consists of feeding a plastic compound in powdered or granular form from a hopper through metering and melting stages and then injecting it into a moldy. After a brief cooling period, the mold is opened and the solidified part ejected. Injection-molding machines can be arranged fur manual operation, automatic single-cycle operation, and full automatic operation. The advantage of injection molding are:
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