Rotational Molding


This article presents all the information you need to know about rotational molding. Read further and learn more about the following:

  • Overview of rotational molding and its history
  • Types of rotational molding machines
  • Rotational molding processes
  • Materials used in rotational molding
  • And much more…

Rotational Molding

Rotational molding, commonly referred to as “rotomolding”, is a plastic casting technique used to produce hollow, seamless, and double-walled parts. It uses a hollow mold tool wherein the thermoplastic powdered resin is heated while being rotated and cooled to solidify. The molded parts from this process are generally valued for their durability and strength. rotomolding companies

Unlike other types of molding processes, rotational molding has no pressure involved which makes the tooling inexpensive. There is no maximum size of tooling that can be used; therefore, it is ideal for producing very large parts. There are also few restrictions when it comes to part design, giving the designer freedom to add complicated details.

The rotational molding process has been traced back to the ancient Egyptians, who created ceramics hundreds of years ago. The first application of a more advanced rotational molding process than what the Egyptians used is the production of artillery shells in 1855 and hollow chocolate eggs by the Swiss in 1910 to create a uniform wall thickness and density. In these periods, there were several patents registered to document the nature of this casting process. However, it was regarded as a slow process and some challenges were encountered, leading to the process not being popularized.

During the 1940s, this process was used to create doll heads and other small toys from polyvinyl chloride plastisol resin using an electroformed nickel-copper plastic. The set-up consisted of only electric motors and gas burners and the finished part was quenched with cold water. This method had attracted many industries to adopt this in their production process, which led to the manufacturing of road cones, marine buoys, and armrests.

Nowadays, rotational molding is used in a variety of applications, producing larger and more complicated parts. The nature of the process is better understood and equipment design is significantly enhanced. The long heating and cooling cycles remain a major bottleneck for some manufacturers. The development is focused on the modification of rotational molding equipment by developers to accommodate increasing demand.

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