About Rotational Molding
Rotational molding (BrE: molding), also known as rotomolding (BrE: rotomoulding), is a plastics molding technology ideal for making hollow articles. It is a casting technique, but unlike most other plastics processes, there is no pressure involved. Molds for the process are relatively inexpensive as they do not have to withstand pressure, and therefore relatively short production runs can be made very economically.
It involves a heated hollow mold that is filled with a charge or shot weight of the material. It is then slowly rotated (usually around two perpendicular axes), causing the softened material to disperse and stick to the walls of the mold. To maintain even thickness throughout the part, the mold continues to rotate during the heating phase and avoid sagging or deformation during the cooling phase.
Advantages of Rotational Molding
Rotomolding is used to make a very diverse range of products. The process offers the product designer exceptional freedom as just about any shape can be produced. There is almost no limit to the size of moldings, and there are thousands of applications.
Look around and see all the plastic parts you see in use every day: car components, drink bottles, bags, even the computer you’re currently working on. Rotomolding has several unique characteristics and advantages compared to other molding processes.
Chemical stability
Plastic can withstand various chemical components, making it a perfect solution for intermediate bulk containers and other containers.
Durability
Plastic parts are significantly impact resistant and do not dent. Parts can also incorporate metal inserts in high-stress areas. Plastic does not rust. Even stainless steel products are susceptible to rust in welded spots.
Ability to do small qty
With less expensive tooling, roto-molding makes it possible to do smaller qty on products. Many of our customers find it economical to do production batches as small as 10 pieces.
Easier to modify production
Fabricated rotomolds are relatively simple, which means that minor changes can be made to an existing mold to accommodate your changing production needs.
Superior strength
Some factors contribute to the superior strength of rotomoulded parts: durable new plastics, consistent wall thicknesses, one-part construction and corrosion resistance.
Lower Cost
Because there is no interior core to manufacture, tooling for rotational molding parts is less expensive than tooling for other types of molding. When compared to most durable metals, plastics are substantially more cost-effective.
Aesthetics
With rotomolding, a wide range of colors is available. Because the color is solid throughout the piece, there’s no unsightly chipping of color. Rotomolding also gives you the option of including a color logo right on the rotomolded piece and it cannot peel or flake away. And because rotomolding allows greater control over the design, you can address the part’s style and its function.
Greater design flexibility
Rotationally molded pieces can be designed and manufactured to fit just about any space available. Often parts that are assembled from multiple pieces can be consolidated into one rotomoulded part. That improves design possibilities. And the fewer parts, the fewer chances for part failure.
Consistent wall thickness
Traditionally, metal components are weakest at the corners – the exact areas where the parts endure the most stress. With injection molding or blow molding, it isn’t easy to achieve total consistency in wall thickness. With rotomolding, the constant rotation allows the polyethylene to coat every surface evenly.
Material options
Moxperts offer a wide variety of certified alloys for rapid insert injection molding services. If the material is not listed, feel free to contact us for a customized solution.
- Cross-linked polyethylene (PEX)
- Linear Low-Density Polyethylene (LLDPE)
- Medium Density Polyethylene (MDPE)
- High-Density Polyethylene (HDPE)
- Low-Density Polyethylene (LDPE)
- Cross Link Polyethylene (XLPE)
- EVA Copolymer (EVA)
- Polyvinylchloride (PVC)
- Nylon
- Polycarbonate (PC)
- Polypropylene (PP)
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