Design & Decoration

Design

The impact of rotational moulding on the design of plastic products is still underappreciated by many other industries. This technique has not only enabled the creation of innovative structural shapes to enhance the stiffness of polyethylene but has also cleverly used geometry to address and conceal manufacturing challenges.

The insights gained from rotational moulding are only now being applied to other technologies. Rotational moulders have developed special features, such as kiss-off points, to enhance the load-carrying capacity of relatively thin-walled, shell-like mouldings.

Part designers must adapt to the generous radii and relatively coarse surface textures inherent to the process. Additionally, rotational moulding is labour-intensive, and until recently, its technical understanding lagged behind other processes like blow moulding and thermoforming. This is partly because, unlike other plastic manufacturing methods, rotational moulding relies on the coalescence and densification of discrete powder particles against a rotating mould cavity wall—a phenomenon extremely difficult to model accurately. Another reason is the lack of academic interest compared to other processes such as compounding, extrusion, and injection moulding.

To strengthen the part, designers can include kiss-offs, foaming, internal ribs, or double walls. While most moulds use only two parts, some designs may require multi-wall moulds. Product designers commonly use Finite Element Analysis (FEA) to ensure a product is fit for purpose, relying heavily on information provided by material suppliers.

Designing for rotational moulding is a specialised field requiring thorough knowledge of the process and its impact on the final part. We offer a comprehensive PDF resource to help your designer become familiar with the process and another PDF focused on adding stiffness to your rotationally moulded parts.

Decoration

Materials for rotational moulding come in a wide range of colours, so decoration may not always be necessary. However, to maximise your product’s appeal and reinforce your brand, there are fantastic decoration options available. Moulders can mix colours to give your part a stone, marble, or vibrant, funky look.

Clever use of materials can achieve effects ranging from a stone-like appearance to a delicate lace finish on parts of your product.

Many products feature colourful, permanent graphics added during or after the moulding process. The design possibilities are limited only by your imagination and the part’s parameters. These graphics become a permanent feature of the product and can include individual serial numbers for tracking and matching production records.

Products can also be decorated with specialised spray paints, as regular paint doesn’t adhere well to polyethylene. These specialty paints allow for unique designs or consistent patterns on complex shapes.

If aesthetics aren’t a priority, you can still mark or decorate your part using metal plates or imprints.

No matter your decoration needs, rotational moulders have a solution to suit them.