Rotational molding - stable products without built-in stress


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. You can read more about different industries via the links to the right.
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 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. 
•    Products approved for contact with foodstuffs such as drinking water. 
•    All our materials are UV-resistant.

“We are happy to help our customers choose the technology that is best for each specific project”

For very large product runs, and where the article size is less than 2m, blow molding may be a good alternative to rotational molding as manufacturing process. The higher initial tool cost is offset both through high production capacity and very long service life.
We are also able to offer manufacture of blow-molded products through our sister company, Blowtech. Many different aspects may be benefited by the respective methods. We are happy to help with advice and the choice of method.