What is Rotational Moulding?
Rotational moulding, or roto-moulding, is a method of manufacturing hollow plastics. It is a low-pressure, high-temperature process that can make simple or complex-shaped objects seamlessly.
Common rotational moulding materials include polypropylene, nylon, polycarbonate, plastomers, thermoplastics, PVC, and foams.
The global rotational moulding market is estimated to reach a value of £6.7 billion by 2031, growing at a rate of 2.1%. The increasing demand for biodegradable materials in automotive, agricultural and construction industries accounts for this growth. As a result, manufacturers are looking for more innovative and sustainable solutions for optimised rotational moulding processes.
Where is Rotational Moulding Used?
Manufacturers use rotational moulding for the following products;
- Cooler tanks
- Storage tanks
- Kayaks
- Automotive components
- Litter bins
- Floats
- Road signs and cones
- Playground equipment
- Furniture
- Toolboxes
- Dashboards
- Ducting
And much more.
Benefits of Rotational Moulding
Benefits of rotational moulding range from:
- Uniform wall thickness ensures high product strength and durability.
- High-quality finishes with no sharp edges and great aesthetics.
- Low tooling costs ensure high production volumes.
- Complex or simple shapes
- No limit on the size of moulded products makes it great for large structures.
- Allows for simultaneous moulding of different products, thus increasing production rate.
- Highly stable products due to lack of exposure to high pressures.
The Rotational Moulding Process
The following steps comprise the rotational moulding process;
- Mould loading: Loading a hollow metal mould with a predefined quantity of powdered plastic resin equivalent to the weight of the end product.
- Mould heating: The mould starts to rotate in an oven. As the mould rotates, the entire surface of the heated mould has a melted plastic resin coating.
- Mould cooling: Removing the hot mould from the oven begins the cooling cycle. The mould continues to rotate even in this phase, during which it is usually exposed to high-velocity air jets and, in some cases, nebulised water.
- Part ejection: Once sufficiently cooled, the product is removed from the mould. The resin powder is placed in the mould again, beginning the repeat cycle.
Lubricants for Rotational Moulding
Lubrication plays a crucial role in the rotational moulding process. Through proper lubrication of the rotational moulding machinery using high-performance lubricants, manufacturers achieve the following benefits:
- Reduced wear and friction improve durability, safety and efficiency.
- Resistance to humidity and water avoids water damage and repairs.
- Smooth, noiseless operation reduces rattles and squeakiness.
- Corrosion and rust protection avoids maintenance and repairs.
- Increased lifespan of components ensures less requirement for repairs and maintenance.
- Effective thermal regulation resists extreme temperatures, preventing damage.
Molykote D-321R is a dry, air-curing lubricant used on rotational mould clamping pliers without contaminating the surfaces in contact. It provides life-long lubrication, compatibility with other lubricants and anti-friction properties.
Molykote P-74 is a metal-free, solid lubricating paste that is used on threaded connections, shafts, guides and bearings in rotational moulding. It is particularly well-suited to high-temperature applications, providing low dispersion of clamping forces and crack prevention.
Molykote Separator Spray is a silicone lubricant that can be used as a release agent in particularly complex points in rotational moulding. It offers a wide temperature range and excellent release properties.
Krytox 227 is a special infusible grease based on PFPE/PTFE technology that is used for arm lubrication in rotational moulding. It operates effectively at high temperatures (above 200°C) and for long relubrication intervals.
In addition to rotational moulding, our lubricants have been used effectively in managing vibrational loads, reducing thread failure, lubricating bearings, avoiding micro-welding of pipes, and sealing industrial furnaces, proving their reliable performance in extremely challenging environments.
We also provide solutions for other methods of plastic manufacturing including; injection bonding, resin transfer moulding and silicone rubber mouldmaking, in addition to solutions for plastic bonding.