Previously, we shared a brief overview of the rotational moulding process, covering its basic principles and applications. In this follow-up article,
we take a closer look at two key components that directly impact the success of any rotomoulded product: the moulds and the materials used during the process.
Pictured above: CNC-machined aluminium moulds, designed and manufactured by the Contact Plastics development team.
Choosing the right mould is essential for producing high-quality plastic components. Below are the three main types of rotational moulds used in the industry:
Fabricated steel moulds are made from laser-cut and welded mild steel sheets. They are the most affordable option, ideal for producing simple, heavy-duty parts.
Advantages: Lowest initial cost
Disadvantages: Less accuracy and detail, not suitable for curved edges or embossed features
Cast aluminium moulds are created using a positive form made from wood or fibreglass. These moulds provide better heat distribution and allow for more design complexity.
Advantages: Better wall thickness consistency, improved design flexibility
Disadvantages: Rougher matte finish, no mirror polish
Applications: General-use plastic products requiring medium detail
CNC aluminium moulds are precision-milled from solid aluminium blocks (typically 6082-grade). These moulds offer the highest level of accuracy and finish quality.
Advantages: Micron-level precision, any surface texture, suitable for complex designs
Disadvantages: Higher manufacturing cost
Applications: High-end products, assemblies requiring tight tolerances
Rotational moulding uses powdered polymers that melt and flow evenly during the moulding process. The most commonly used materials are:
LLDPE (Linear Low-Density Polyethylene): Offers strength, flexibility, and impact resistance. Ideal for most applications.
HDPE (High-Density Polyethylene): Used where a stiffer, more rigid material is needed.
PP (Polypropylene): Good for higher temperature or chemically resistant products.
All materials at Contact Plastics are UV-stabilised for at least 3 years, ensuring outdoor durability.
We also offer a range of specialised polymers for specific industry needs, including:
Diesel- and AdBlue-resistant plastics
Anti-microbial and anti-static materials
Flame-retardant compounds (e.g. Polycarbonate)
Anti-odour materials for enclosed spaces
High melt-flow powders to reduce pinholes
Ultra-smooth surfaces to prevent staining or residue build-up
Advanced moulding options such as double-layer moulds and high-strength foam cores are available for increased strength, insulation, or fire resistance.
Whether you need a simple steel mould or a high-precision CNC aluminium mould, Contact Plastics is here to help. We’ll assist with material selection, mould development, and product optimisation from start to finish.