Rotational molding is a manufacturing process used to create hollow plastic products. Essentially, it involves rotating a mold filled with plastic as it heats and cools, allowing the material to coat the interior walls evenly.
The process can be broken down into a few key stages:
The Rotational Molding Process Explained
Based on the provided reference, the core steps of rotational molding are:
- Filling the Mold: A hollow mold is filled with powdered plastic resin. This resin, typically polyethylene, is the raw material that will form the final product.
- Heating and Rotation: The mold, containing the resin, begins rotating bi-axially (simultaneously rotating on two axes). It is then transferred into an oven. The continuous rotation ensures the plastic powder is evenly distributed inside the mold.
- Melting and Coating: While the mold continues to rotate in the oven, the resin melts. The molten plastic coats the walls of the mold layer by layer, building up the desired wall thickness as it adheres to the hot surface.
- Cooling: Once the plastic has fully melted and coated the mold walls, the mold is moved to a cooling station. It is cooled until the resin hardens into the desired shape. This cooling can be done with air or water mist. Rotation typically continues during the initial cooling phase to maintain uniform wall thickness.
- Demolding: After the plastic has solidified, the mold is opened, and the finished part is removed.
This method is particularly effective for producing large, hollow items with complex shapes and consistent wall thickness, such as storage tanks, kayaks, playground equipment, and large containers.
