The Issue(s) With Injection Moulding


Injection moulding is a popular method used to create moulded products in large-scale production runs. The reason injection moulding tends to be popular within mass production is that the very high initial tooling costs associated with injection moulding must be justified with high volume production runs, so as to provide a return on investment. Moreover, these operations of mass production tend to have much longer lead times than alternative methods as – due to the high volume of units produced – a longer period of time needs to elapse before project completion.


Furthermore, many of the inputs associated with injection moulding rely heavily on raw materials sourced from overseas. A reliance on foreign supply chains for raw materials and/or production processes consititues a risk within today’s uncertain climate. For example, as we have seen displayed extensively due to the COVID-19 pandemic and to other macroeconomic shocks such as Brexit, supply chains are incredibly sensitive to disruption and are much less stable than one might presume. Because of this, there is much security to be found in a production process which does not rely on overseas supply chains. Thus, wherever possible, it makes reasonable business sense to reduce your production process’s exposure to overseas supply chains in order to mitigate the risk of lengthy delays in output.


(It is worthwhile noting that all of Cox Wokingham’s capabilities are performed right here in the UK).


The high initial cost of injection moulding, the need for large-scale production runs, the reliance on foreign supply chains, and extended lead times means that for many businesses, injection moulding is simply not the appropriate solution for their production needs.


The Solution: High Pressure Forming


High pressure forming (HPF) is a method of production in which material is precisely shaped through the application of air that has been compressed to a very high pressure. This highly pressurised air is also heated so that the material being shaped reaches its softening temperature and becomes malleable. The material – printed film – is held in place by clamps within a forming tool where the heated, pressurised air is then applied.


The HPF method uses negative tooling. This means that rather than creating products by forming them over a tool – such as in thermoforming – outputs are produced by forcing material into a cavity (within the tool), as opposed to the other way around. This method allows for the creation of incredibly intricate products.


High Quality at a Fraction of the Cost


High pressure forming allows you to create components that rival – in terms of their precision, detail, and aesthetic – injection moulded products, but at a fraction of the cost. This forms the primary benefit of utilising HPF within your production runs: high quality at a sensible pricepoint. 


This cost benefit is achieved as the tooling expenses of HPF tend to be far lower than those required when developing tools for alternative methods (such as injection moulding). 


Moreover, due to the lower initial costs, it takes far less production volume in order to cover the outlay of the initial tooling with the output produced. As such, HPF is a great method for small-to-medium sized production runs as less production volume is required to justify the setup expense of tooling. And, crucially, the components produced provide the same aesthetic outcome achieved through injection moulding – just at a much lower price.


High Detail & Precision


Because of HPF’s negative tooling method as described earlier, the finished products produced through high pressure forming can be made to an incredibly high level of detail and precision. Thus, components created through HPF can adhere to rigorous and highly exact specifications. This allows for outputs produced via HPF to be used in an extremely wide variety of applications. For example, as you can imagine, within the aviation, automotive, rail and medical industries it is absolutely essential that components created for use within these fields meet their specifications precisely. Any deviation from the design required could result in catastrophic errors with terrible consequences.


The ability of HPF components to be precise and detailed in their design is exemplified through their capacity to achieve undercuts. Small lips underneath high pressure formed components mean that they can slot perfectly into counterpart components (such as other HPF products). This level of detail is simply not possible to achieve with other methods of production, such as thermoforming. In thermoforming, if you were to try and apply an undercut to the material being formed, it would simply turn inside out when being removed from the tool. Intuitively, this limits the application of thermoformed products relative to their high pressure formed cousins.


The Benefits of High Pressure Forming


Overall, parts produced through high pressure forming:


  • Can be made to an incredibly high level of detail and precision
  • Can adhere to extremely rigorous specifications and designs
  • Have an extensive potential for use within a broad range of applications and industries
  • Have enhanced functionality when compared with components produced through alternative methods
  • Can be made at a fraction of the cost when compared to other methods of production
  • Require less volume in order to justify initial tooling expenses
  • Do not rely on overseas supply chains (when produced within the UK – such as when delivered by Cox Wokingham) and are therefore less susceptible to disruption and delay.


High Pressure Forming Services from Cox Wokingham


At Cox Wokingham Plastics, we offer the full spectrum of services from Concept Support, Tool Making, Material Selection, Fabrication and Assembly to complement our Vacuum Forming and High Pressure Forming process. If you would like more information about what we do, or more help deciding which moulding option is best for you, please visit our website or contact a member of our team on or call 0118 977 4861 and ask for Iain Carstairs or Shaun Hamill. We at Cox Wokingham look forward to being of service to you.



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COX’s expertise in the planning and production of prototype pieces is your shortcut to the right solution. Right on specification. Right on practicality and performance. And right on budget.

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COX offers a comprehensive range of thermoforming services, including vacuum forming, press forming and line bending.

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As well as having the skills and experience to push the limits of High Pressure Forming, COX also offers the technology in the shape of its huge GEISS T10 Pressure Former machine.

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