The process is simple in concept. Heat is used to melt and fuse a plastic resin in a closed mold. Unlike most other plastic processes, no pressure is involved. The parts are molded in a virtually stress-free state, thus, the finished parts are extremely strong and durable. There are three basic stages to our process once the resin is loaded into the mold: heating and fusion of the resin to the mold walls, cooling the resin, and unloading the part from the mold to begin the process again.
After the loaded molded is moved into an oven, the mold is rotated on two axes at low speed (bi-axial rotation (see diagram below). As heat penetrates the mold, the resin adheres to the mold's inner surface until it is completely fused. The mold is then cooled by air and/or water spray while still rotating, lowering the temperature in a gradual manner. The mold is then opened, the formed part removed, and the mold recharged for the next cycle.
A variety of materials are available. The most widely used are polyethylene's and plastisol's. Other materials include: Nylon, Polypropylene, EVA, and other specially formulated compounds.
Advantages of Rotomolded Products
Unlimited design possibilities - with proper design, parts from other processes that are currently assembled from several pieces can be molded as one integral part - thus saving on expensive fabrication & assembly costs.
Economical tooling costs as compared to injection or blow molded processes.
Substantial weight reduction from metal and fiberglass process.
Ideally suited for runs as small as 100 pieces annually or as large as 10K annually.
Strong outside, stress-free corners - so parts can take abuse.
Double walled parts for extra rigidity and parts can be designed with little to no draft.
Economical medium to large sized parts can be molded.
Ability to mold in fasteners of all types for exceptional pull out strength.
Ability to mold in graphics, logo's , warning labels, and identification of all types.