Roto Moulding Process

How does rotational moulding / roto moulding work?

As the animation shows, rotational moulding (also known as roto moulding) is extremely simple yet affordable and highly effective. It also offers real advantages over injection and blow moulding which include:

  • Low start-up costs: Roto moulded tools cost a fraction of the price of injection or blow moulding tools so new products can be brought to market comparatively cheaply and quickly.
  • Flexible process: Rotational moulding can be run for one-off products if necessary, making the process ideal for small to medium sized batch runs. Injection moulders generally require runs of several hundred products for the process to be cost-effective.
  • Wall thickness: Roto moulded products offer a uniform wall thickness of between 3-5mm and in some cases up to 8/9mm – depending on the application.
  • Surface texture: Different surface textures can be easily achieved on any product by applying a shoot peen (rough textured) finish that is masked off to leave certain areas of the tool smooth.
  • Range of applications: The practical use of roto moulded products is wide-ranging, from garden and street furniture to tractor parts, kayaks and equestrian products. Take a look at some Case Studies to see what we mean!
  • Grades of material: We offer a choice of different grades of material including anti-bacterial material for use in the food and hygiene sectors. We also offer black recycled material as standard – made from our off cuts it’s a cheaper option for many applications.

Excelsior Ltd. Excelsior Ltd.


Contract moulding

Rotational moulding is an extremely versatile process for the manufacture of a vast range of plastic products and components – it’s why we’ve used it to bring our customers’ plastic products to life for more than 40 years.

Find out more about out Contract Moulding.

The clever bit

Many of the customers we produce bespoke products for visit our factory to see how the process works.

Polyethylene powder is measured out by an operative and placed into the mould which is clamped shut and moved into an oven chamber. The tool is heated up to between 220°C and 400°C while rotating on two axes at speed. As the rotating tool heats up, the powder begins to melt and adheres to the inside of the mould, progressively building up a layer over the inner surface.

Once the plastic is completely fused to the surface, the mould is then automatically withdrawn from the oven and cooled. After approximately 45 minutes to 1 hour, the plastic product is removed from the mould and allowed to cool further. For products of a technical nature, we normally use a wooden cooling jig at this stage as it helps ensure the product doesn’t shrink too much and assists with maintaining critical features.