The injection unit melts the polymer resin and injects the polymer melt into the mold. The unit may be: ram fed or screw fed.

 

The container holding a supply molding material to be fed to the screw. The hopper located over the barrel and the feed throat connects them.

 

The ram or screw that applies pressure on the molten plastic material to force it into the mold cavities.

 

The reciprocating-screw machine is the most common. This design uses the same barrel for melting and injection of plastic.

 

The alternative unit involves the use of separate barrels for plasticizing and injecting the polymer. This type is called a screw-preplasticizer machine or two-stage machine. Plastic pellets are fed from a hopper into the first stage, which uses a screw to drive the polymer forward and melt it. This barrel feeds a second barrel, which uses a plunger to inject the melt into the mold. Older machines used one plunger-driven barrel to melt and inject the plastic. These machines are referred to as plunger-type injection molding machines.

 

Barrel is a major part that melts resins transmitted from hopper through screws and structured in a way that can heat up resins to the proper temperature. A band heater, which can control temper atures in five sections, is attached outside the barrel. Melted resins are supplied to the mold passing through barrel head, shot-off nozzle, and one-touch nozzle.

 

Hydraulic motor located inside bearing box, which is connected to injection cylinder load, rotates screw, and the melted resins are measures at the nose of screw. There are many types of injection cylinders that supply necessary power to inject resins according to the characteristics of resins and product types at appropriate speed and pressure. This model employs the double cylinder type. Injection cylinder is composed of cylinder body, piston, and piston load.

 

The clamping unit holds the mold together, opens and closes it automatically, and ejects the finished part. The mechanism may be of several designs, either mechanical, hydraulic or hydromechanical.

 

There are two main types of injection molds: cold runner (two plate and three plate designs) and hot runner – the more common of the runnerless molds.

 

Steel plates on a molding machine to which the mold is attached. Generally, two platens are used; one being stationary and the other moveable, actuated hydraulically to open and close the mold. It actually provide place to mount the mould. It contains threaded holes on which mould can be mounted using clamps.

 

A device that actuates the chuck through the aid of pneumatic or hydraulic energy.

 

Tie bars support clamping power, and 4 tie bars are located between the fixing platen and the support platen.