Injection Moulding Tool Basics

For creating plastic products, the injection moulding process allows for many identical components to be produced quickly, cost-effectively and identically. This process involves filling an injection moulding tool with liquefied thermoplastics. The plastic material then cools inside the mould and solidifies into a finished product. The mould itself is often the most expensive part of the process to produce, and there are many different styles and types of moulds available.

Tool Design

A typical injection moulding tool consists of two plates, called the injector mould and the ejector mould. These two plates fit together to form a cavity into which the plastic material is injected. The liquefied plastic is pushed into the mould through a sealed nozzle called the sprue that connects the mould to the heated barrel where the plastic is melted. The mould is kept cool with a flowing coolant such as water, which allows for the plastic to solidify quickly upon entering the mould. After cooled, the two plates separate and the solid piece is ejected.

Tool Construction

Since initial creation of the injection moulding tool is one of the major expenses of the moulding process, constructing a mould that is durable and consistent over time is essential. High-performance aluminiums, beryllium-copper or common tooling steel are optimal choices for moulds that are able to withstand the high temperatures and pressures associated with the process. More mild metals and alloys may be used to make short-production run moulds or those used for prototyping.

Tool Size

When beginning the plastic injection moulding process, many people only consider the size of their finished components when selecting the size of their mould. Many times, however, alternate configurations of the mould can be created to produce more finished products with a single “shot” of plastic material. Small components such as zipper toggles, for instance, are produced in batches of hundreds per shot. This leads to per-piece costs and manufacturing time being greatly reduced.

Chess Plastics is a UK leader in plastic injection moulding. With state-of-the-art machinery and skilled operators who always put quality first, they are ready to meet all of your plastic manufacturing needs. Learn more online at