Rotomolded

Rotomolded refers to products made by the rotomolding process, a plastic forming method used to produce hollow, often large, parts. In rotomolding a mold is filled with resin and heated while the mold is rotated about two perpendicular axes. The resin coats the interior surface evenly as it is distributed by the motion, building up walls of the desired thickness. After forming, the mold is cooled while continuing to rotate to preserve shape, then opened and the finished part is demolded.

The process is characterized by its ability to create seamless hollow parts with relatively thick walls and complex internal geometries. Because the entire interior is coated by rotating resin rather than being injected, there are few or no weld lines. The method is well suited for producing large containers and enclosures, and it allows for simple inserts, texturing, or integrated features molded into the part. Surface finishes depend on the mold’s interior and can range from smooth to textured.

Materials commonly used in rotomolding are thermoplastics, with polyethylene resins—high-density, medium-density, and low-density polyethylene—being the most prevalent due to toughness, chemical resistance, and ease of processing. Other plastics such as polypropylene, polycarbonate, acrylics, and sometimes PVC may be used for specific applications. Color and additives are typically incorporated with the resin before molding.

Applications of rotomolded parts include water and chemical storage tanks, portable coolers, drums, large containers, playground equipment, kayaks and canoes, automotive components, and electrical or utility housings. The method offers design flexibility, relatively low tooling costs for large parts, and production of durable, hollow components suitable for outdoor or rugged use.