Rotomolding, also known as rotational molding, spinning molding, and rotation molding, is a hollow molding method for thermoplastic materials. The process involves adding plastic material to a mold, which is then continuously rotated along two perpendicular axes while being heated. Under the influence of gravity and heat energy, the plastic material inside the mold gradually and uniformly coats, melts, and adheres to the entire surface of the mold cavity, forming the desired shape. The product is then cooled and solidified.

Principles of Rotational Molding

The basic processing process of rotational molding is quite simple. It involves placing powdered or liquid polymers into a mold, heating them while the mold rotates around a vertical axis, achieving both self-rotation and rotation around the axis. Afterward, the mold is cooled to form the product. At the beginning of the heating stage, if powdered material is used, a porous layer is first formed on the mold surface, which gradually melts during the cycle to form a uniform, even-layer thickness; if liquid material is used, it flows and coats the mold surface, stopping completely when it reaches the gel point. The mold is then transferred to the cooling area, where it is cooled by forced ventilation or water spray, and placed in the work area. Here, the mold is opened, the finished product is removed, and the cycle is repeated.