Rotational Molding Process: Application, Materials, Products…

The rotational molding process is one of the most important processes in plastic hollow part production. There are a wide variety of polymer parts can be produced with rotational molding machines. In here we explained;

  • General process characteristics and mechanisms rotational molding process,
  • Materials used and products produced with rotational molding processes.

How The Rotational Molding Is Applied?

Rotational molding process steps illustration(Image Source:

Rotational molding is also called ‘rotomolding’ is the process that, plastic, big, and hollow-thin parts are produced. The shape of produced parts are is generally round.

Powder or pellets of plastic material is placed inside the mold. Required heat is applied to that mold to melt the plastic inside it. Then, the centrifugal force is applied to spread the molten polymer inside the whole details of the cavity.

Water spray is applied to cool and solidify the molten plastic inside the mold, then after solidification, plastic is detached from the mold.

In general applications of the rotational molding process, three workstations are working at the same time to improve the production rate and efficiency. At the same time, there are three molds are attached to the indexing body, which rotates.

This rotation takes place between, loading and a de-loading section of material in which mold is opened and closed. The heating section that mold is heated to melt the polymer inside it. And rotation and cooling section. At the same time, all of these three sub-processes were done in three different molds.

Advantages And Disadvantages Of Rotational Molding Process

The most important advantage of rotational molding over other similar plastic shaping processes such as transfer molding and blow molding, more intricate details can be produced in better dimensional tolerances. And bigger parts can be produced with the rotational molding process.

The downside of the rotational molding process is the slower process cycle which is around 10-15min.

Materials And Products In Rotational Molding Process

Rotomold buoy product example.

Various kinds of polymer materials can be used in rotational molding such as nearly all the thermoplastic polymers. Thermosetting and elastomers are also common materials that are used in rotational molding processes.

In thermoplastics, ABS, polyethylene, HDPE, and polypropylene are the most common materials that are used in rotational molding processes.

As we stated above, large parts can be produced by using rotational molding processes such as; big plastic tanks, big containers, fuel tanks, truck body parts, little inflatable swimming pools, and other inflatable plastic products, canoe hulls, etc.

Conclusion For Rotational Molding Process

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