Rotational Moulding

Rotational moulding is a production method in which plastic powder is heated inside a mold that rotates around multiple axes. As the material melts, it distributes evenly along the walls of the mold, forming a seamless hollow product. Ovun AS uses this technique to manufacture customized components such as buoyancy elements, tanks, and various industrial products. The products can be adapted with additives that provide impact resistance and UV protection and typically have a lifespan of 15–30 years, depending on the application.

Rotational moulding is well suited for producing tanks and containers for liquids and chemicals, buoyancy elements and floatation devices for subsea and offshore use, and customized plastic parts developed for demanding operational environments. Ovun AS has equipment that enables production of units up to approximately 5 meters in length, depending on the design.

The process is cost-efficient because the tooling costs are generally lower than with other methods, and it allows hollow products to be made without welding. Rotational moulding is ideal for both small and medium production runs. Optimized heating and cooling cycles further reduce energy consumption and production costs.

This method offers significant design flexibility and makes it possible to create products with uniform wall thickness and solid construction without seams. The parts have good resistance to mechanical stress, and the materials can be modified to ensure long service life even outdoors. Compared to injection moulding, rotational moulding requires simpler tools and lower initial investment.

The most common materials are thermoplastics such as polyethylene, known for its strength, flexibility, and chemical resistance, and polypropylene, which is used when extra chemical resistance is needed. The choice of material is based on requirements for service life, environmental conditions, and mechanical performance.

Polyethylene expands when heated and contracts as temperatures drop. This can impact dimensional accuracy, which is why careful design and consideration of tolerances are essential. For products exposed to fluctuating temperatures, materials with proven stability over time are used.

Products such as buoyancy elements and floatation devices can be engineered to withstand high pressure, mechanical stress, and long-term exposure underwater. Ovun AS offers modular solutions with material selection and designs tailored to the specific requirements of subsea projects.

Rotational molding generally has longer production cycles compared to methods like injection molding, and there are limitations when it comes to very fine surface details. In addition, thermal expansion and contraction of the material can make it challenging to produce components with very tight tolerances. Ovun AS addresses these challenges through careful mold design, stable process parameters, and thorough quality control.

Yes, these products can be recycled, especially when manufactured in polyethylene. Ovun AS actively works with sustainable material choices and solutions that support a circular economy. We also accept discarded rotationally molded products from our customers for recycling or responsible handling by agreement.

Polyethylene (PE) is a durable and flexible thermoplastic that resists chemicals, impacts, and mechanical loads over time. It can be supplied with additives that protect against UV radiation, making it particularly well suited for products such as containers, buoyancy modules, and technical enclosures.

Material selection is based on factors such as chemical resistance, mechanical strength, flexibility, exposure to sunlight, and desired service life. Ovun AS assists customers in finding solutions that meet both functional and economic requirements.

Energy consumption can be reduced through the use of modern ovens with uniform heat distribution, proper insulation, and optimized heating and cooling cycles. These measures help lower the environmental footprint of production.

The process generates minimal waste because there is no cutting or excess material as in some other methods. The plastics used can be recycled, and the products’ long lifespan reduces the need for replacements. Ovun AS is also working with recycled raw materials and other sustainable alternatives. Learn more about our environmental initiatives at [link to sustainability page].

Production begins by filling the mold with plastic powder or liquid resin. The mold is then rotated while heated so that the material melts and coats the interior evenly. After the mold is filled, it is cooled to solidify the part. Finally, the product is removed and thoroughly quality-checked to ensure consistent performance.