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Learn About the Benefits and Failures within Roto Moulding

Martin December 12, 2020

The process in which any material or liquid that is melted, poured into a rigid frame called mould or matrix, and is cooled to form the desired shape, is called moulding. In the engineering world, this process gets usually done with plastic material. Thus, the entire technique is also known as custom plastic moulding.

There are several types of plastic moulding techniques, but the only one that produces highly durable plastic products keeping the environment in mind is- Rotational moulding. With the growth of modern technologies, there has been a significant increase in the number of roto moulders in Australia and other continents.

To understand the impact of Roto moulding in the plastic industry and why it is preferred or rejected, it is essential to be aware of all the nitty-gritty surrounding the technique.

What is Rotational Moulding?

Rotational Moulding or Rotomoulding is a form of thermoplastic moulding technique used to develop large hollow products such as water tanks, marine buoys, kayaks, road cones, etc. with evenly thick walls.  In the past decade, this technique has witnessed rapid growth in the plastic industry with the introduction of modern technologies.

How Does Rotational Moulding Take Place?

The process consists of four key steps:

  1. Mould Charging

The technique begins by loading a powder or liquid resin into a metal mould. This mould is generally made up of steel aluminium to save costs.

  • Mould Heating/Rotation

Once the mould gets filled with the liquid or powder, it begins rotating at high speeds surrounded by high temperature in an oven till the liquid resin covers/coats the walls of the mould. When the mould gets rotated, a centrifugal force gets generated, which results in the formation of evenly thick-walled products.

  • Mould Cooling

This step involves the cooling of the mould so that the ideal shape of the desired product gets retained.

  • Demoulding

To conclude the process, the end product gets demoulded or ejected out of the mould. This end product gets launched in the market.

Benefits of Roto Moulding

Rotational Moulding gets preferred over other moulding techniques due to the following benefits it offers:

  1. Low Tooling Costs

In Roto Moulding, the tooling costs are way lower as compared to the other techniques, which results in lower start-up costs. Rotational moulding is the first choice for small and new businesses in the plastic industry because very little material is wasted during the entire process, thus, making it economical.

  • High Strength Products

Any plastic or metal product endures the most stress on its corners. Roto moulding enables the formation of thicker corners, thus, resulting in highly robust products.

  • Highly Durable Products

Since all the parts of the end product get moulded in one solid piece, therefore, there is no need for techniques like welding, which can make the product weak.

  • Environment Friendly

During the entire production process, no harmful toxins or chemicals get released. Moreover, very little material gets wasted.

  • Ease of Modification

The moulds that get used in rotational moulding are highly intricate to make a diverse range of customizable and changeable products. Since thermoplastics like polyethylene get used, they can be re-melted and re-used to form a different product or make changes in the existing one.

  • Exceptional Thickness Control

The constant rotations enable the powder to coat all the walls of the mould evenly. Therefore, there is consistency in the thickness of the walls of the final product, which cannot get achieved by any other moulding method.

  • Attractive Appearance

Rotomoulding provides you the ability to control and enhance the surface of the final product. The delicate metal that gets used allows the addition of letterings, images, fine-detailing, etc. Serial Numbers, bar codes, and even logos in different colors can get integrated without any fuss.

Failures of Roto Moulding

There is no plastic moulding technique that is perfect for use. Therefore, Roto Moulding comes with its set of disadvantages:

  1. Time Consuming

The technique requires a lot of patience and time. When the mould gets rotated at a high temperature, it must get rotated slowly, so that it covers the entire surface of the mould getting used. In this modern competitive world, the consumption of precious time is a huge disadvantage as a lot of time gets eaten up before the product can get launched in the market, leaving you behind the competition.

  • Strict Material Restrictions

When using Roto Moulding, there are restrictions in place for the material that can get used. The technique is limited to using poly-based resins such as polycarbonate, polyethylene, polyamide, to name a few. And these materials have to be broken down into a uniform powder. Therefore, only some material can get utilized.

  • Low Tolerance Level

A parameter that makes roto moulding different from others is that there is no pressure used in the process. During rotation, some areas can pull away from the walls of the mould and reduce heat transfer. This absence of pressure results in decreased tolerance level and distortion in parts of the end product.

  • Lack of Repeatability

The tooling in roto moulding gets primarily made of cast aluminium or fabricated sheet metal, which is soft by state. Therefore, there is a restriction that the tooling must get replaced or refurbished after 3,000 cycles. This restriction can lead to quality issues due to a lack of repeatability.

  • High Labor Cost

Rotational Moulding requires a significantly large workforce when compared to other techniques, which results in an increased labor cost.

In Conclusion, the most suitable way to decide whether or not rotational moulding will be the right choice for your business is to figure out the size of production you are planning to do annually. If you are running a small business and are required to produce less than 3,000 parts per year, Rotomoulding can prove to be extremely cost-effective. However, if you are not bothered about the tooling cost and are seeking to break the threshold of 3,000 parts produced annually, it is advised to prefer a different form of moulding technique.

There are several companies worldwide that offer plastic moulding services. However, if you are looking for custom plastic moulding in Australia, there is none better than Rudplas Rotomoulders.

Rudplas roto moulders Australia is a family-owned and operated business involved in the rotational moulding industry for over 25 years. Rudplas specializes in the manufacture of bulk materials handling products, such as industrial trolleys, laundry trolleys, water tanks, etc. All products get manufactured from top quality UV stabilized food-grade polyethylene, which makes their products lightweight, easy to clean, and impact and weather resistant.

You can visit them in Melbourne for custom plastic moulding, or browse their website and contact them further for their services.

About Author


Rudplas Rotomoulders is an Australian family owned and operated business that has been involved in the rotational moulding industry for over 30 years. Rudplas specialises in the manufacture of bulk materials handling products, which includes a large range of industrial trolleys and laundry trolleys. Rudplas also manufactures a selection of water tanks in popular sizes and colors as well as a variety of service station products. At Rudplas, we also have the ability to mould your unique customer based rotational moulded products. Rudplas’ line of products are manufactured from top quality UV stabilised food grade polyethylene. This makes our products light weight, easy to clean and impact and weather resistant. We pride ourselves on working with our customers and the flexibility to modifiy and customise trolleys to best suit individual needs puts the power of choice in the hands of the customer. All of our products are manufactured under ISO 9001:2008 conditions for quality assurance and are backed by our manufacturers warranty. View all posts by Martin →

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