PLASTICS INJECTION MOULD STRUCTURE

What is an Injection Mould?

An injection mould is an arrangement of steel parts, in one assembly. It has one or
several hollow cavity space built in it to the plastic product shape; where plasticised
plastics are injected into filling the cavity / cavities to form the plastic products.
The hollow cavity space is also called impression. Two members form this space:
1. The cavity, which is female portion of the mould, gives the moulding its external
form.
2. The core, which is male portion of the mould, forms the internal shape of the
moulding.



The different design principles of functional units can be used as a basis for the
classification of injection moulds. Moulds can be distinguished by the following criteria:
1. The processed material
2. The basic design
3. The runner system
4. The ejector system
5. The number of cavities
6. The profile of parting lines
7. The size of mould


 Two-Plate Mould

A two-plate mould consists of two plates. It is a basic mould. The feed system is
located at the cavity plate, while the ejector system at the core plate.
Main Components:
1. Core plate
2. Cavity plate
3. Feed system
4. Ejector system
Characteristics:
1. Simple design
2. Two mould halves
3. One parting line
4. Opening one direction
5. Demoulding by gravity and ejector system

Product:
All kinds of mouldings without undercut




1. Feed System

- An internal passageway in the mould which provides a flow path for plastic
material from the machine’ nozzle to the cavity (impression). The feed system
normally consists of the sprue, runner and gate.
2. Ejector System

- The part of the mould to which the ejector element is fitted. This system
normally consists of the ejector plate, retaining plate, return pin and ejector
pins.





Three-Plate Mould

Main Components

1. Runner plate
2. Cavity plate
3. Core plate
4. Feed system

Characteristics

1. Two parting lines.
2. Movement of floating plate is actuated by latch or stripper bolt.
3. Two steps opening movement.

Product
Automatic separations of moulding and runner while the runner is removed from the
other parting line between the runner and cavity plate.