Rotomolding: What It Is
Rotational Molding (often called rotomolding) is a cost-effective process of making hollow plastic parts of limitless size by tumbling powdered resins inside a heated mold. The combination of continual rotation, plus controlled heating and cooling within the mold, achieves a consistently uniform diffusion of plastic along the inside of the mold walls. Resins used in rotomolding include HDPE, LLDPE, and high-density polyethylene.
Rotomolding: The Benefits To You
The many advantages of rotomolding provide you with key “edges” in achieving your product performance goals and staying competitive within demanding markets.
The Production Edge
- Suitable for both low volume and annual volumes of up to 100,000 parts.
- Small or large part capabilities - from a few inches to 20 feet or more.
- Hollow parts, enclosed pieces, and parts with openings, can all be achieved through rotomolding.
- Faster tooling lead times enable quicker part-to-market capability.
- Nearly stress-free parts because no external pressure is used during rotomolding.
- Minimal cross- section deformation or warpage.
- The uniformity of rotomolded wall thicknesses can be maintained to within ±10 percent – significantly better than other molding processes.
- Ability to change part wall thickness with the same mold.
- Good finish and surface detail of parts.
The Design Edge
- Extreme freedom and flexibility in part design resulting in optimal finished part performance.
- Complex geometries possible in a single seamless part.
- Can be designed with double-wall construction for strength or urethane foam filling for additional strength or insulation.
- Wall variation can be designed into the mold to create stronger parts due to thicker outer corners or other features.
- Ability to use of molded-in graphics, metal inserts, reinforcing ribs, kiss-off ribbing and undercuts.
- Multiple piece tooling enabling one-piece design freedom of complex shaped parts for elimination of post-molding assembly.
The Cost Edge
- The rotomolding process is an economical method of producing seamless, one-piece, hollow parts with complex shapes and diverse sizes that would be costly or impossible to produce using other plastic processes.
- Mold simplicity and relatively low operating pressures enable molds to be built using aluminum a less expensive and easier to manufacture material.
- Family of molds make high volume production of part cost effective.
- Can eliminate the need for secondary assembly.
- Multiple parts can be molded as one and finished as several reducing both part and tooling cost.
- Polyethylene is a low-cost resin.