What is Rotational Moulding?

Rotational moulding is a highly versatile manufacturing process that allows for virtually unlimited design possibilities, and offers design advantages over other moulding processes, parts that are usually assembled from several pieces can be moulded as one. This reduces fabrication and assembly costs.

The process also has a number of inherent design strengths, such as consistent wall thickness and strong outside corners that are virtually stress free. If additional strength is required, reinforcing ribs can be designed into the part.

Rotational molding delivers the product the designer envisions. Together with designers the moulder can select the best material for the application, including materials that meet food contact, heavy metal free and other environmental and technical requirements. Additives to help make the part weather resistant, flame retardant, or static free can be specified.

Inserts, threads, handles, minor undercuts, flat surfaces that eliminate draft angles or fine surface detail can all be part of the design. Designers also have the option of multi-wall molding that can be either hollow or foam filled.

Cost advantages 

Rotational moulding is very cost-effective when compared to injection and blow moulding for both small and large parts.

Production costs for product conversions are reduced because lightweight plastics replace heavier, often more costly materials. This makes rotational moulding as cost effective for individual prototypes as for large production runs.

The rotational moulding process

The rotational moulding process is divided into 4 steps:

1. Loading 

2. Heating   3. Cooling 4. De-moulding 
 A mould is mounted on a mould carrier and charged with plastic powder.
 Under biaxial rotation the mould is heated until the powder is properly sinted and forms a uniform layer on the inside of the mould.
Under continued rotation the mould is cooled until the melt is solid.
The mould is opened and the final product is removed from the mould.