Jobec UK Rotational Moulding

Your one-stop shop for moulded products


Rotational moulding is the process of creating hollow plastic parts/products, for example, water and fluid tanks, grit bins, road barriers, canoes, boats, floating pontoons, etc. Rotational moulding produces strong durable products that are weather and chemical resistant and can last many years in harsh environments. The moulding process involves melting plastic powder to a semi-liquid state that is then spread evenly over the inside of a hollow tool during the rotation period. After cooling, the product reverts back to a strong rigid hollow structure.



A predetermined amount of polymer ( plastic) either in powdered or liquidform is poured into a hollow metal mould which is made from either Steel orAluminum. The amount of plastic used in the metal mould will be equivalent to the weight of the finished product. Rotational moulding has one big advantage of no waste. All the plastic poured into the mould is used.











Once the plastic has been poured in, the lid of the mould needs to be securely clamped into position. The mould is then moved into the heat source where the rotation starts. Rotations are normally around 10-12 rev min, rotating in one axis slowly in both directions, the mould will tilt on its second axes back and forth. This ensures the plastic is evenly distributed throughout the mould. By changing the speed of revolutions and tilts, together with the dwell time between movements, it’s possible to control the thickness of the walls of the end product in areas that need extra strength.











After the heating cycling is complete, the mould is removed from the ovenand the cooling cycle begins. This involves using air blows and sometimes fine mists of water to slowly cool the mould. If the mould is cooled too quickly the product may become distorted due to imbalance of heat from inside to outside surface tempratures. When the product is cooling, it starts to naturally shrink away from the inside surface of the mould. Once cooled, if the adequate draft angles have been provided then the product should slide out. Release agents are used to help this process. The product is removed from the mould and the joint lines are de-flashed. Depending on the product, additional assembly can then be carried out on the part.



The benefits of the rotational moulding process is a relatively uniform wall thickness throughout the product and secondly, the hollow moulding can have design and structural advantages difficult or impossible to achieve by other methods such as blow-moulding or vacuum forming. Technology, tooling and finishing makes rotational moulding an ideal choice for hollow products – such as rotationally moulded plastic tanks – with advanced benefits. Low cost, short lead times, intricate design features and little or nopost mould finishing are all within the advantages of rotational moulding. Extra strength, sound deadening and insulation properties are increased with foam filling, either as an inner skin or whole cavity. Threaded studs, nuts, handles, hinges, labels, locks and many other items can also be moulded in during process.











Got any questions? Visit us at or email any enquiries to:



Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s