Rotational moulding, also called rotomoulding, is a thermoplastic processing method for producing hollow parts, from the most simple to the very complex, from very small to very large.

The Process of Roto-Moulding

The rotomoulding process consists of the following steps:

1. A predetermined amount of plastic, either in powder or liquid form, is deposited in one half of a mould.

2. The mould is closed.

3. The mould is rotated bi-axially inside an oven.

4. The plastic sinters (heats and transforms from solid powder to liquid) and forms a coating over the inside surface of the mould.

5. The mould is removed from the oven and cooled while still rotating.

6. The mould is opened and the hollow part is removed.

Roto-moulding is characterized as being an atmospheric pressure process that produces nearly stress free parts. An essential requirement is that the plastic withstands elevated temperatures for relatively long times.

Multi-arm machines allow multiple moulds of different shapes and sizes to be run together. Complex parts that are difficult or impossible to mould any other way can be roto-moulded. With experience and expertise it is possible to mould uniform wall thickness parts, unlike blow moulding or twin-sheet forming. Roto-moulded parts have no seams or weld lines. Normally the only controls on the process are the turn speed & ratio, the oven time & temperature, the cooling rates/methods & time.

Advantages of Roto-Moulding

Rotomolding technology is prevalent, making it one of the rapidly growing industries in the last decade. There are numerous advantages of rotational molding, from design versatility, reduction of environmental impact, use of lighter materials, and meeting of demand. Why choose rotational molding as the best technology for your next plastic projects? Below are a few advantages that every part designer should be aware of.

The materials used are long-lasting and flexible

At Roto Dynamics, our rotomolded plastic products are made from polyethylene protected from the hazardous UV Rays from the sun. As you all know, Ultraviolet rays from the sun make products to fade quickly and degrade with time. Unlike metals, rotomolded plastic is free from rust, and they do not corrode easily, meaning that your products will be durable. Besides, the products made from our roto molding company are powerful since the walls are thick; hence, they are not easy to break.

Minimum environmental impact

One of the rotational molding advantages is its minimum environmental impact. During the rotomolding process, no chemicals or dangerous toxins are released hence making it environmentally friendly. Unlike metals and concrete, very few materials are wasted when manufacturing is done using plastics. One fantastic feature about plastics is that they are 100% recyclable hence simple to reduce your carbon footprints. This means that for every plastic item that is recycled, fewer materials are mined from the earth, therefore, reducing its impact on the environment.

Wide range of designs

With the rotomolding process, it is simple to generate a variety of shapes, majorly because when hot plastics are placed on a mold, they take the shape of the mold. Many molding processes have few options to choose from, but with rotomolding, any form can be designed from the process. This makes it ideal to be used in many industries. Our roto molding company provides you numerous designs of your choice.

Variety of size options

Compared to other molding processes that accommodate a few sizes, rotational molding allows for diverse sizes to choose from. 

Low cost

The initial production cost for rotational molding is way cheaper compared to other molding processes. The low cost incurred is for machining the mold. Before heating, the mold requires finished pieces added to it like color plastics, internal pipes, and metal threads. This saves you both your time and money.

The production process takes a shorter time

Another rotational molding advantages is the process time. Compared to blow molding or perhaps injection molding, rotomolding takes a shorter duration of time. The speed at which we can produce rotational mold, makes it ideal for quick orders or rush orders. For instance, in our roto molding company, production can start in two months or less.

Disadvantages of Roto-Moulding

Like any other plastic molding process, rotational molding has its share of disadvantages, which include :

Few material options

One of the disadvantages of rotational molding is that you have less material options. The raw materials we use in rotational molding must be changed from granules to a fine powder and excellent thermal stability. The only material suitable to be used in the process is resin.

High process durations

The rotational molding process can take as long as three hours to complete one section involving eight turns.

The astounding expense of crude oil material

The cost of crude oil is high because of the costs incurred in converting the materials to powder and the added materials.

High work costs

The use of robots in rotomolding has not been proclaimed hence requires a large workforce to take care of the operations. The cost incurred in paying the workers is high, which would have otherwise been made easier if robots were doing the work.

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