Considering Moulds, Materials and Components in Injection Moulding Design

Injection Moulding & Tool Design Consultancy

Designing a product for injection moulding requires a wide array of factors to be taken into consideration. While the principle of injection moulding is relatively simple to grasp, modern mechanised injection moulding processes are very intricate and involve many elements in order to produce the highest quality, precision plastic components.

Design services, like those provided by APL,  can make the processes of product development and delivery operate much faster and with greater economy. Specialists with experience designing for the injection moulding process will have the best understanding of how to design a product that takes all of the variables involved into account.


Unless the form of the complete product is relatively simple such as a plate or a basic container it will need to be separated into simpler component parts. This allows the piece to be fabricated using the injection moulding process which by its nature imposes various design limitations on the pieces that are moulded.

A finished product may also be made up of plastic and non plastic components that are made using other manufacturing processes such as extrusion or bending. An example of this might be a pen that is half metal half plastic. The plastic component is formed using injection moulding and the metal component is formed with a variety of methods such as die pressing.

Ensuring the finished components fit together properly requires expertise in injection mould design. Understanding how the properties of materials, heat and the injection moulding process will shape the finished product allows injection mould designers to produce an optimal product.

A single component may include several sub components. Processes such as 2-Shot moulding and Insert moulding allow different metal or plastic components to be incorporated into the mould in order to form a single component.


The specific materials to be used in the finished product will have an effect on many of the injection mould design decisions. The choice of material will be based on the requirements of the product. There are thousands of different types of polymer, thermo plastic and elastomers to choose from, each with its own distinct set of properties.

A plastic injection moulding design consultancy service can help determine the suitability of particular polymers to the intended function of the finished product. The designer will also have to take into consideration specific mould design requirements for a particular plastic. It may have different heating, cooling, flow and other properties that will affect the requirements of the mould.

The stability of the final product is also something that needs to be evaluated at the design stage. Different materials will have different structural integrity. It may be the case that a piece needs to be reinforced either with a harder plastic or a metal component. This can be done with insert or 2-shot moulding processes.


The design of each mould has numerous considerations of its own. A comprehensive flow analysis will help determine the most effective and efficient mould design. A flow analysis looks at how the particular polymer will flow through the mould, how it will cool and how it will react to various structures within the mould.

The position of gates and cooling elements are two of the main factors that mould flow analysis can help optimise. Any weaknesses in the design can be determined at this point as can the potential for warping of the finished product.

Drafting is an important design element that the designer will have to take into consideration. This affects how the component is released from the mould and has to be varied according to factors such as the texture of the piece’s surface and the properties of the material.