An Intro to Plastic Rotational Molding


Plastic is everywhere in our lives. From cell phones, televisions, and accessories to appliances and home improvement, plastic can be found in many different components around the home. This component is incredibly versatile, and has many different techniques to ensure each application works properly. One technique is custom rotational molding. This form of plastic molding, or rotomolding as it sometimes is called, can be complex. Here is everything you need to know about custom roto molding.

What is it?

Rotational molding involves a hollow mold that is heated, which is then filled with a specific weight of material. Then this plastic material is slowly rotated, and this motion allows the softer material inside to stick to the walls of the mold. As a way to maintain an even layer of coating, the mold will continuously rotate. However this is for both the heating and cooling process, especially when it is cold to prevent sagging or deformation of the plastics.

Plastic molding equipment

The plastic molding equipment involved in rotational varies depending on size. In general, the machine as a whole will include molds, a oven to heat, a cooling chamber, and mold spindles. These spindles are attached to a rotating machine, which ensures the even coating of the plastic in the machine. The different types of rotational molding machines include:

Rock and roll machine

This type of machine specializes in long and narrow parts. They are in shape of a clamshell, and will rotate the plastic 360 degrees in one direction, while also tipping the mold 45 degrees horizontally in the other direction so the plastic is moving fluidly. Some of the newer classifications of this machine utilize hot air when instead of an oven to heat the mold.

Vertical up and over machine

With these type of machine, the loading and unloading part is in the front instead of the top. They are known for being energy efficient as their heating and cooling chambers are compact and very powerful.

Shuttle machine

These machines actually shuttle the plastic in between the heating and cooling chamber. The arms turn the molding bi-axially, and are cost efficient because they can handle a large amount of product in a small amount of time.

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