Thermoforming is a manufacturing process that offers excellent design flexibility, cost-effectiveness and fast turnarounds for companies that require high-quality plastic parts.
Although widely used across the world, many people still have questions about the process, with many of our customers at Cox Wokingham Plastics asking us how it works, what the benefits are and more.
With over 80 years of thermoforming experience, we have created this guide to answer the most common thermoforming questions.
What is thermoforming and how does it work?
Thermoforming is a manufacturing process that transforms plastic into complex, 3D shapes using a custom mould.
This process works by heating the plastic material to a temperature at which it becomes pliable and then stretching it around the mould using vacuum, pressure or a combination of both to form the shape.
Once the formed plastic has cooled and solidified into the new shape, the part is trimmed to remove any excess material before undergoing any additional finishing processes, such as CNC (Computer Numerical Control) machining, drilling, routing or assembly.
Compared to injection moulding, thermoforming offers benefits including lower tooling costs, faster lead times and greater flexibility when producing large, complex plastic components in low to medium production volumes.
Does thermoforming require a mould?
Yes – thermoforming requires a specialist mould which defines the final shape of the part. This mould is often referred to as a tool or jig, and is manufactured during a process known as toolmaking.
Typically, the mould is first prototyped using inexpensive materials such as plasterboard or modelling clay. This allows the design, fit and functionality of the component to be tested and refined before moving on to production tooling.
Once the prototype has been approved, the vacuum forming and CNC trimming tools are manufactured, typically from aluminium, PU resin or model board, depending on the application, production volume and budget.
Tools are precision-engineered to ensure consistent quality and repeatability, enabling thousands of impressions to be made before replacement.
Compared to injection moulding, thermoforming tooling is significantly more cost-effective and quicker to manufacture, especially when partnering with a UK manufacturer.
What are the two main types of thermoforming?
Thermoforming is an umbrella term that encompasses the two main types of thermoforming processes – vacuum forming and pressure forming.
What is vacuum forming?
Vacuum forming is the most common type of thermoforming that uses vacuum suction to form plastic into a desired shape.
This process works by removing the air between a mould and a heated plastic sheet, causing the material to pull tightly around the mould, ensuring an accurate and consistent finish.
What is pressure forming?
As a more advanced method of thermoforming, pressure forming uses compressed air to force materials into a mould.
Unlike vacuum forming that solely relies on vacuum pressure, pressure forming applies both positive air pressure above the plastic sheet in addition to the vacuum being applied below.
The additional force helps this process achieve superior detailing, with the materials being able to wrap around intricate moulds or sharp corners. The improved definition also makes it ideal for incorporating embossed logos, branding, product names and other design features directly into the finished component.
When should I choose high-pressure forming over standard vacuum forming?
If the shape you’re looking to thermoform requires complex details, textured surfaces, sharp corners or embossed brand images and logos – you may want to consider high-pressure forming over vacuum forming.
If the mould has simpler geometrics or has larger dimensions – you may be better off using standard vacuum forming.
What plastics can be thermoformed?
A wide range of plastic materials are used in thermoforming, with the most suitable material depending on the application and aesthetic requirements.
Plastic materials that are commonly thermoformed include:
- HIPS (High Impact Polystyrene)
- ABS (Acrylonitrile Butadiene Styrene)
- Acrylic (PMMA)
- PETG (Polyethylene Terephthalate Glycol)
- PP (Polypropylene)
- Polycarbonate (PC)
- PVC (Polyvinyl Chloride)
What size parts can be thermoformed?
The maximum part size will ultimately depend on the capacity of the thermoforming machine and the size of the tooling.
Despite the misconception that thermoforming is only limited to the production of small parts or components, the process can produce components that are several metres in length.
Vacuum forming is generally better suited to producing larger components due to its wider forming area, while pressure forming excels at manufacturing smaller to medium-sized parts that require exceptional detail and a high-quality cosmetic finish.
Is thermoforming suitable for low-volume or one-off production runs?
Yes, thermoforming is suitable for low-volume and one-off production runs too.
Given thermoforming’s shorter lead times and cost-effective production process, it is an ideal choice for projects where regular or batch production isn’t commercially viable.
Cox Wokingham Plastics – your thermoforming partner
Since our inception, Cox Wokingham Plastics have been at the forefront of thermoforming, supporting specialist industries such as passenger transport – manufacturing parts used in aerospace, rail, buses and coaches.
With an experienced in-house tooling team, advanced vacuum forming equipment and a state-of-the-art GEISS T10 pressure forming machine, we provide a complete manufacturing solution from concept and tool design through to forming and finishing.
We have the capability to produce high-quality components in a wide range of materials and sizes, with forming capacities of up to 3,000mm x 1,500mm x 750mm.
If you still have questions about thermoforming or are interested in our thermoforming services, get in touch: https://www.coxwokingham.com/