Rotomolding Process

What is rotomolding?

Rotational molding, also known as rotomolding, rotary molding, etc., is a hollow molding method for thermoplastics. The method is to add plastic raw materials first into the mold, and then the mold is continuously rotated along two vertical axes and heated. Under the action of gravity and thermal energy, the plastic raw materials in the mold are gradually uniformly coated and melted and adhered to the mold cavity. The whole surface is formed into the required shape, and then cooled and shaped into a product.

Forming Principle

Step 1.

Add LDPE powder to mold

Step 2.

Heat and spin

Step 3.

Cool and demoulding

The basic process of rotational molding is very simple. It is to put powdered or liquid polymer in a mold, heat it, and the mold rotates and revolves around a vertical axis, and then cools to form. At the beginning of the heating stage, if a powdery material is used, a porous layer is formed on the surface of the mold, and then gradually melts with the cycle process, and then a homogeneous layer of uniform thickness is formed; if a liquid material is used, it flows and flows first. Coated on the surface of the mold, when the gel point is reached, the flow stops completely. The mold is then transferred to the cooling work area, cooled by forced ventilation or water spray, and then placed in the work area, where the mold is opened, the finished part is taken away, and then the next cycle.

Advantages of rotomolding products

  • Adjustable and uniform product wall thickness.
  • Integrally formed, no internal stress, no seam outside.
  • Suitable for molding large and super large parts. 
  • Easy to realize complex structure.
  • Color and material type can be changed easily.
  • Rounded corner makes product safe

Tool Making

Step 1.

Pour into sand cavity with melton aluminum

Step 2.

Machined both outside and inside mold surface

Step 3.

surface treatment and frame installation

Double side surface machined makes the mold more light and would be heated more uniform.

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