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Key Factors that determine the cost of Plastic Injection Moulding

Image of selection of plastic component parts injection moulded by PNP
injection moulding plastic parts by PNP

Having been in business for 40 years, one of the most common questions that we are often asked by our clients is-

“What are the key factors that will influence the cost of my injection moulding project?”

In this blog article, we will discuss the main aspects that drive the cost of a plastics injection moulding project.

The most significant up-front cost within your plastics injection moulding project will always be the tooling element. Tooling costs can range from anywhere between £4,000 - £20,000+. Whilst this is undeniably a high investment cost, it is imperative to remember the following two points:

1. The mould tool is at the heart of the manufacturing process, it is therefore essential that the tool is designed and constructed properly to efficiently produce your parts throughout the life of your project.

2. The cost of the tool should be amortised throughout its lifetime as the cost is distributed amongst hundreds or thousands of parts. Thus, injection moulding is an ideal process to mass-produce plastic parts affordably.

Part Size

The part price is largely determined by the machine used and the cycle times needed to produce the part. Larger moulds that use for example 250-ton lock machines require additional set-up time which subsequently increases the cost. Cycle times are governed by the wall thicknesses, part size and complexity which increases machine & material use and has a cost impact on the part.

If a part is larger, it will require a larger mould tool, which often takes longer to manufacture. If the part has a larger number of cavities, it is likely that you will need a larger press size which in turn increases costs such as electricity, set-up costs and space. It is worth noting however that the savings from increasing the number of cavities should offset the cost of increasing the injection moulding press size.


Each plastic moulded part will differ in its design and complexity. A detailed part may require locally hardened inserts or a completely hardened cavity. Additional costs can also be driven by specialist surface finishes. Elements such as these will contribute to the overall plastic moulding cost. Simply put, the more complex the mould design, the higher the cost.

A complicated tool with side actions and/or unscrewing needs will reduce the unit cost however it will increase the cost of the tool. A commercial decision will need to be made around secondary operations being carried out or the design of a fully automatic tool.


Various products have different customization requirements such as surface texture, colour dyes, stamping, and other aesthetic requirements.

The lower the number of customizations required to the moulded part, the more you will save on cost. It is therefore imperative to vigilantly consider the requirement of each aesthetic finish prior to implementation. Reducing these requirements is an easy way to cut down on the overall cost of the project.

Material Selection & Quantity

A large proportion of the plastic injection moulding costs are dependent on the type of plastic material and the quantity that you use.

An extensive range of plastics are available for injection moulding, from polypropylene, polycarbonate, and ABS, to nylon. These polymers offer product designers a broad choice of colours, chemical & mechanical properties.

Before you decide which material, you want to use, consider the application of the plastic part. Evaluate the essential features needed within the part to get optimal functionality. Research your options to see whether you can achieve it with a lower-end polymer. Sometimes, lower-end polymers with some fillers and additives work equally well as a higher-end material.

We hope you have found this blog post of interest. If you are considering plastic injection moulding for your component part, then why not schedule a free consultation with us?   We are Plastics Injection Moulding experts, and work closely with our clients to understand their unique requirements, objectives, and challenges. 

To arrange your consultation either call us on 01453 833 388 or email us


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