Rotational molding, also known as rotomolding, is a plastic molding process that produces hollow parts. The main characteristics of this process is that the process is carried out without pressure and the mold is rotated slowly, usually rotating on two perpendicular axes.
The rotomolding process consists of four phases:
- Material loading: the mold is opened, loaded with plastic material (previously accurately measured) in powder form and closed.
- Heating: The mold is introduced into the oven and begins to rotate around two orthogonal axes. The rotating process will not stop until the demolding phase. This causes the plastic material to adhere to the inner walls of the mold, obtaining a hollow or semi-hollow piece.
- Cooling: Once the heating phase is finished, the mold goes to the cooling chamber, where it is cooled with air. This phase is what makes the plastic maintain the desired shape while it solidifies to allow its demolding.
- Demolding: The mold stops rotating and the mold is opened. The molded part is removed and a new cycle is started.
However, this process has been known for many years. In fact, as early as the 1920s, this technique began to be used. However, it was not until the 1960s that a major development in the process began. This development in technology and molding has continued to the present day, as rotomolding is currently experiencing a major boom. With rotomolding, a large number of hollow articles can be produced that can be fully or partially closed, with single or multiple walls.
In Gestión de Compras we provide our customers with a personalized treatment in the design, development and manufacture of parts made by rotational molding. We manufacture both standardized and customized products according to customer requirements and guidelines, in a wide range of sizes and materials.
- Low tooling cost. As this process is carried out without pressure, this means that the molds are more economical and the process can be profitable for low production volumes. The production cost of a rotational molding mold is less than 5% of the cost of an injection mold.
- It is easy to make complex shapes. Rotational molding easily accommodates production complexities such as reinforcing ribs, molded inserts and different surface textures.
- Uniform wall thickness. This process achieves consistent wall thicknesses with corners tending to be thicker. This increases the strength and stiffness of the product.
- Manufacture of the product in one piece, hollow without the need for welds. The wall thickness is uniform and can be increased or decreased, without the need to modify the mold.
- Innovative and creative, possibility of creating different parts for different sectors.
As for its drawbacks, the biggest problem is that the production cycle takes a long time. The production rate is at most 10% of that of injection molding.
Some of the utilities of rotomolding parts are:
- Water and chemical tanks (up to 50 m3).
- Kayaks, canoes and boats.
- Road safety products and street furniture: litter garbage cans, road cones, bollards, traffic dividers,
- Bollards, traffic dividers and traffic signs.
- Automobile industry: mudguards, diesel tanks, control panels for tractors, etc.
- Children’s toys and games.