Rotational molding is a stress free process that creates plastic parts that are both extremely durable and long lasting. This multi-step process involves a mold rotating on two axis that is filled with material, usually polyethylene, which is heated, then cooled.
Most other manufacturing production processing of plastic requires force to be used to mold the plastic. Rotational molding utilizes movement to mold the part making the rotational molding process stress free. Once a mold is filled with polyethylene powder it begins to rotate on two axis. It is moved through the oven where the rotating arm continues to move as the polyethylene powder is warmed and liquifies. This molten, near liquid plastic is continually coating the mold building the walls of the part. Learn more about the rotational molding process by watching the video below.
Rotational molding is a four-stage process. Let's help explain some of the details of each step of the rotomolding process below.
Stage One: Loading the plastic resin into the mold.
The first step is loading the resin in the mold. Pulverized material in a fine powder form is loaded into the prepared mold. The mold is then secured closed and rotated to ensure no powder is able to escape.
Stage Two: Moving the mold into the heating chamber of the oven while rotating on two axis at a low speed.
The mold is moved into the heating chamber of the oven while rotating on two axis at a low speed thus both distributing and fusing the resin.
Stage Three: Moving the mold into the cooling chamber and cooling by air or water spray or a combination of both, while still rotating.
Pre-cooling and Cooling- After completing the cook cycle, the mold is then moved to the cooling chamber and cooled by air or water spray or a combination of both, while still rotating, thus lowering the temperature in a gradual manner.
Stage Four: Unloading the finished part from the mold.
Unloading - The mold is opened, the finished part is removed and the mold is prepared and loaded for the next cycle.
Rotomolded products can be produced from a variety of materials. Typically the material selection is based upon performance criteria and expectations of performance of each part. Learn more about the differences in materials for rotational molding.