Rotomoldings

Rotomoldings, or rotational molding, refers to a manufacturing process used to produce hollow plastic components by heating a hollow mold filled with plastic resin. The mold is rotated about two perpendicular axes during heating and cooling, allowing the material to coat the interior surface and form a uniform hollow part.

Resin is loaded into the mold, which is heated and rotated. As the mold spins, the resin melts and coats the interior walls; the process is repeated to achieve the desired wall thickness. After reaching the target thickness, the mold is cooled while still rotating and the part is removed.

Common materials include polyethylene (HDPE and LDPE), polypropylene, PVC, and other polyolefins. Benefits of rotomolding include the ability to produce large, one-piece hollow parts with uniform wall thickness, simple tooling relative to other molding methods, and good impact resistance. Complex geometries and integrated features can be molded without seams.

Limitations include longer cycle times, moderate to low production volumes, and sometimes rough surface finishes or thicker walls in small parts. The process generally requires substantial mold size and maintenance, and initial tooling costs are high for large parts but lower for simple shapes.

Applications span storage and chemical tanks, water and wastewater equipment, portable containers, pallets, kayaks and boats, and consumer goods. Quality control focuses on wall thickness uniformity, absence of porosity, and leak testing, with materials chosen for chemical compatibility and temperature requirements.