Rotational moulding

 

Rotational molding is a cost-effective manufacturing process in which plastic products are cast using a steel or aluminium mould. The products are cast in one piece without joints, are free from built-in tension and make the best use of raw materials by optimising the desired wall thickness and strength. The finished products are very robust and impact-resistant. The most common raw material used is polyethylene (PE), a thermoplastic with many good properties. Excellent chemical resistance, negligible moisture absorption and high elasticity give polyethylene a wide range of uses. 

Our experience in rotational molding dates back to the 1950s and, through close cooperation with customers and suppliers, we have become specialists and sought-after partners for successful projects all the way from design, production and quality control to finishing and, not least, good logistics solutions. 

Why use rotational molding?

Rotationally molded products are always hollow bodies – in other words, they are built up as a shell. Examples of suitable products and applications include: Tanks and containers, outdoor furniture, lamps, cones and barriers, covers (ex), pipes (ex), splash guards, spa baths, safety boxes, outdoor toys, tool boxes, buoys & floats.

Our machine park can manufacture products from the size of a handball up to about 25m3 and with a wall thickness nominally between 3-10mm. The molds we cast in have low investment costs, making rotational molding a suitable process for smaller product runs, from 100 pieces a year and up. Connections such as threads and bushes can often be cast directly during the process or may be subsequently installed in our assembly department. 

A sustainable product

The raw material that we use for rotational molding is high-quality plastic in powder form that has been carefully tested and verified by us. We are also able to adjust the material selection on the basis of the product’s requirement, the basic raw materials usually being PE (Polyethylene), PP (Polypropylene) or PA (Polyamide). Our raw materials should not be confused with simpler disposable plastics, for these are plastics with a long service life that may be recycled numerous times.   

All our production waste is ground down and recycled. We maintain a strong focus on sustainability, as may be seen through our investment in Nordic Plastic Recycling, a recycling company creating the conditions for sustaining materials in a closed cycle.

Of course, being sustainable is about much more than just the choice of materials. We work with sustainability at all levels and aim to minimise our environmental impact by making active sustainable choices in relation to materials, processes and transportation. We work continuously with our logistics and shipping optimisation, making sure, for example, that our products are optimised for shipping from as early as the design phase. 

THE HISTORY OF PLASTIC ROTOMOULDING

 

People were desperately seeking for a technique to produce large plastic items in a reasonably easy manner. They made experiments with molding polyethylene granules in some primitive iron molds, which were warmed up and the result was thereafter.

One could not melt granules into finished tubs, but the possibilities were apparent. Plastic Powder was the case, it could be seamlessly fused into finished products. For many years, only simple rotation about an axis was used. It was much too difficult to fill the molds entirely with powder and after a time drain the excess material out again, and shiny products are finished.

Double rotation is the thing to do today and has been for many years. The rotation is set by product form and nature, and one can thus obtain a uniform thickness within approx. 1mm.

New high-tech churns provide complete uniform powder.

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The benefits of rotational molding

•   Great freedom in product design means that products can be made-to-order for the best function and appearance. The method allows for complicated      shapes with fine details.
•    Rotational molding is best for the production of hollow bodies from small to very large formats (0.1 litre - 25000 litres). 
•    Products are manufactured in one piece without joints (seamless), providing maximum strength and minimising the risk of cracks and leakage.
•    The low cost of moulding tools means even smaller product runs can be profitable.
•    The option of building in many functions such as threads and bushes provides cost-effective solutions.
•    Products with very good chemical resistance that are also recyclable.
•    Wide temperature range for use: -30֯C. to +60֯C.
•    Low weight in relation to product size. 
•    Corrosion-free products.
•    Choice of product colour according to RAL with stable colouring. 
•    All our materials are UV-resistant.

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