Newcomers to the world of plastic injection moulding are often met with a whole new vocabulary that can seem quite confusing and intimidating at times. That’s why we’ve compiled this three-part post of some of the more common terms to help ease some of that uncertainty.


A substance added to a resin to enhance or improve certain characteristics of the final product. A popular trend today is to add biodegradable additives to plastics to reduce pollution and environmental degradation caused by plastics.


The change of a material with time under defined environmental conditions, which leads to either to improvement or deterioration of certain properties.


This term refers to a composite material made up by blending polymers and copolymers with other polymers or elastomers under selected conditions. They are usually designed to retain the best characteristics of each material.


Annealing is the process of heating and cooling plastic moulded parts in a controlled fashion to relieve the internal stress of the part.


This occurs when molten resin flows back out of the mould and returns to the runners.

Backing plate

A plate used as a support for the mould cavity block, guide pins and bushings in an injection moulding machine.


The section of a moulding machine that contains the feed screw, also the section where resin is heated and mixing occurs.


This is a part defect which appears as a small bubble or blister on the surface of a part and it is generally created by gas or air bubbles.


To from a “plastic” object by pouring a fluid monomer-polymer solution into an open mould where it finishes polymerising.


A depression or set of depressions in a mould which forms the outer surfaces of the moulded articles.

Click here to read Part 2.

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