How Much Does Plastic Injection Moulding Cost? A Plain-English Guide for New Buyers

If you are new to injection moulding, one of the first questions you will ask is how much it costs. It is a perfectly reasonable question, and it is often met with a frustrating answer: "it depends".

The good news is that every quote is built from the same handful of cost drivers. Once you understand them, it becomes much easier to read a quote, compare suppliers and plan your budget. This guide explains what each one is and how it affects the price.

What are the two main parts of an injection moulding cost?

Almost every project can be split into two types of cost:

• The one-off investment in tooling. This is the mould tool made specifically for your part. You pay for it once, at the start of the project.

• The cost of each part. This covers material, machine time, labour, finishing, quality checks and packaging. You pay this every time a batch is produced.

  
  

This split explains why injection moulding can look expensive at the start and then become extremely cost-effective as volumes grow.

Why is tooling usually the biggest upfront cost?

A mould tool is a precision-engineered piece of equipment, usually machined from steel or aluminium, that has to produce accurate parts cycle after cycle. Its cost depends on:

• Size of the part. Larger parts need more metal, more machining time and a bigger machine.

• Number of cavities. A multi-cavity tool produces several parts per cycle. It costs more upfront but lowers the cost of each part.

• Complexity. Undercuts, clips and threads often need moving parts within the tool, each adding design and machining time.

• Tool material. Aluminium tools are quicker and cheaper to make and suit lower volumes. Hardened steel tools cost more but can produce hundreds of thousands of parts or more.

• Surface finish. A high-gloss polish or specific texture requires extra work on the tool.

Tooling is best thought of as a long-term asset. Spread across the lifetime of a product, the tooling cost per part is often very small.

How does material choice affect the price?

Material is a major part of the cost of each part, and prices vary widely. Commodity plastics such as polypropylene and ABS are comparatively affordable. Engineering plastics such as polycarbonate and nylon offer more strength or heat resistance and cost more. High-performance polymers such as PEEK sit at the top of the range.

Additives such as flame retardants, UV stabilisers and glass fibre all add cost, as does the weight of the part. Raw material prices also move with global markets, which we covered in our article on why plastic prices are rising. The best value usually comes from a material that meets your requirements without exceeding them.

Why does volume make such a big difference?

Volume is where injection moulding comes into its own. Higher volumes bring the cost per part down in two ways:

• The tooling cost is spread over more parts. A tool used for a few hundred parts carries a much higher cost per part than one used for a hundred thousand.

• Set-up costs are shared across the batch. Fitting the tool and bringing the machine up to temperature takes the same time whatever the batch size.

  
  

For smaller quantities, aluminium tooling, rapid tooling or 3D printed prototypes can help you test a design before committing to a full production tool. Our article on 3D printed moulds explores this further.

How does part design change the cost?

Design has a bigger influence on cost than many buyers expect. Thick walls take longer to cool, and cooling is often the longest stage of each cycle. Very tight tolerances need more precise tooling and more inspection. Undercuts and complex features add moving parts to the tool.

This is why design for manufacture (DFM) reviews are so valuable. Small changes made before any steel is cut can save a significant amount over the life of a product. Our guide, Tips for Designing Parts for Injection Moulding, covers this in more depth.

What about finishing, assembly and hidden costs?

Many parts need work after moulding, such as printing, ultrasonic welding, fitting inserts, assembly or bespoke packaging. Each step adds to the cost per part, so it is worth identifying them early. Using one supplier for all of them cuts transport between suppliers and simplifies quality control.

When comparing quotes, also look beyond the headline price:

• Tool modifications after the tool is made can be costly

• Minimum order quantities can tie up cash in stock you do not need yet

• Shipping, duties and longer lead times from overseas suppliers can quickly close the gap on a lower unit price

• Quality documentation such as inspection reports and material certificates may be essential for your sector

The cheapest quote is not always the lowest overall cost, a point we explored in our article on reshoring manufacturing to the UK.

What information do you need to get an accurate quote?

The more detail you can share, the more accurate your quote will be. Ideally, provide:

• 3D CAD files (STEP is the most widely used) and drawings showing critical tolerances

• Estimated annual volumes and typical batch sizes

• The intended material, or how the part will be used if you are unsure

• Colour, finish and any secondary operations

• Your timescales and any certification requirements

If you do not have all of this yet, that is fine. A good moulder will help you work through the gaps.

Quick answers to common cost questions

Is injection moulding expensive? The upfront tooling cost can be significant, but the cost of each part is usually low. For medium and high volumes, it is one of the most cost-effective ways to produce plastic parts.

Do I pay for the tool every time I order? No. Tooling is normally a one-off cost, and repeat orders are charged at the cost per part.

What has the biggest effect on cost? Usually the combination of tool complexity and volume, followed by material choice and part design.

How Amey Plastics can help

Amey Plastics has been making tools and moulding plastic parts in Hampshire for over 30 years. Our in-house toolroom, supported by a network of audited UK and Far Eastern toolmakers, lets us recommend the right tooling approach for your volumes and budget. With 12 injection moulding machines and in-house design, prototyping, post-moulding and distribution services, we can manage your project from concept to delivery.

If you have a project in mind, or would like help understanding a quote, our team would be happy to talk it through. Call us on 01730 266525 or email sales@ameyplasticsltd.co.uk.