Injection – Mould

To manufacture plastic details using the injection moulding process we need three basic components: injection moulding machine, material (plastic) and mould (matrix).

We will try to explain what the mould is, in the following material.

The injection mould or so called matrix, is a combination between metal plates, bushes, columns and other parts. All the moulds are almost the same.


Fixing ring: it is for the right mold fixing to the injection machine. The ring diameter corresponds with fixing diameter of the injection machine.

Nozzle: due to the fixing ring the mould nozzle is on the same level as the ejection machine nozzle is. Through this nozzle the melted plastic runs from the screw to the mould.

End plates:  they connect the mould to the machine. The end plates lie on the fixed and on the movable plates of the machine.

Moulds: the plastic detail is formed in these plates (A and B).

Impressions: these are the real shapes where the plastic detail is formed. Аs many as impressions are on the mould so details can produce in one cycle (shot).

Slide columns:  in principle, they are mounted on the fixed part of the mould, but there are exceptions.  Slide columns are for correct mould closing.

Slide bushes: always they are mounted on the part opposite the slide columns part . When closing the mould the columns go into the bushes. In this way they guarantee that both, fixed and movable parts of the mould,  are join correctly, at the same position.

Die block:  it is for strengthen the mould (B).

Ejected pins: they allow for easy removal of the molded plastic detail from the mould. Their number and shapes depends on the material type and detail complexity. Always their movement is from the movable to the fixed part of the mould. They move in previously drilled holes in the die block and mould (B).

Central ejection pin: an ejection that draws the sprue out of the mould nozzle when opening the mould.

Return pins: when closing the mould they help the ejected system to get back to the starting position. They are higher than the ejector pins and they touch the fixed half of the mould before ejector pins touch it.

Ejected plates: ejected pins, central ejected pin and return pins are in these plates. Thanks to the ejected plates and their movement on slide bushes and columns (they are for ejected system) the ejected system is moving on one plane.

Buffers: they form the distance within the ejecting system moves.