RotomoldedPolyethylen

Rotomolded polyethylene refers to hollow, seamless parts produced by rotational molding (rotomolding) using polyethylene resins. The process yields large, complex shapes with uniform wall thickness and no weld seams, making it suitable for items that require a strong, watertight shell.

In production, resin is placed inside a hollow mold in powder or liquid form. The mold is closed, heated in an oven and rotated on two perpendicular axes, causing the resin to melt and coat the interior uniformly. The rotation continues as the part cools, after which the mold is opened and the finished item is ejected. The method favors simple tooling and enables thick walls and integrated features in a single piece.

Common resins include high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE), sometimes with stabilizers for UV resistance or chemical compatibility. Rotomolded parts tend to be impact resistant and weather-durable, with good chemical resistance. Tolerances are generally looser than those from injection or extrusion processes, and surface finishes can be rough without post-processing. The approach allows inserts or fittings to be placed in the mold or added during molding.

Applications range from water, chemical, and septic tanks to portable coolers, storage bins, playground equipment, and even kayaks or boats. Advantages include the ability to make large, complex, seamless parts at relatively low tooling costs and the option to tailor wall thickness. Limitations include longer cycle times and comparatively less precise tolerances, though recyclability of HDPE helps address end-of-life considerations.