Exploring The History Of Rotational Molding

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Rotational molding has an interesting history, and one of the things you should know is that it started with the Egyptians, as they were the first to use the process in creating ceramics. There are many molding processes that have been applied for many years now, and it was a process used by the Swiss, especially when making hollow chocolate eggs.

In the US, especially between 1940 and 1950, rotomolding processes were created mainly for use in making small plastics. However, it didn’t grow in popularity at that time because it was considered to be a substandard process. Over the past few years, many improvements have been applied to the process. We’ll have a look at grangerplastics.com for the historical origins of the rotational molding in this article.

Historical Origins

In the article called “A History of Rotational Molding”, which was written by Noel Mansfield, the process was originally created for the creation of doll heads, and this was mostly during the 1940s. During that time, electroformed nickel-copper was used in creating the mold, while PVC plastisol was the polymer that was used. With time, the new process gained the attention of many within the industry, and after a while, different types of toys were manufactured using the process.


Towards the late 1950s, a better understanding of the process was gotten, and people understood how to apply the process, and other industries started using the process to manufacture different things, including car armrests, marine buoys, and road cones. In the early 1960s, the Engel process was developed, and it was used in creating low density polyethylene. The process involved rotating a mold before cooling methods were applied.

The popularity of the Process

During the 1980s, the process was already mastered in many industries, and it was later on streamlined for larger purposes. This was also enhanced by the increased demand for newer materials with better and more enhanced grades. Today, storage tanks of all shapes and sizes now dominate the industry, and their composition mostly includes polyesters, LDPE, polypropylene, polycarbonates, ABS, and nylon, all of which also complement LPDE and high-density polyethylene.

In 1984, rotational molding was the choice and most preferred method for the manufacture of different types of materials, including affordable white water, sea kayaks, and many more. It’s worth noting that the Queen’s University, Belfast, also played a key role in improving the knowledge and understanding of the rotational molding process. This also includes creating a system that will enhance the continuous in-mold temperature that is used.

There are many reasons why the process is now popular, and today it’s a process that’s used to improve the quality of parts and alsoto lower cycle times. There are also pressurization techniques that help in offering lower cycle time, and this is mostly achieved by applying low pressure to the right areas, especially during the heating phase. Basically, the aim is to speed the process of coalescing the different polymer particle. The aim of this strategy is to help in producing lesser bubbles, within a shorter time frame, unlike when it is done at atmospheric pressures.

Another thing to note is that there are also people who criticize the pressurization technique, and this is mostly due to the dangers that are associated with pressurized parts, particularly the risk of explosion. Today, this is a key reason why pressurization is not yet adopted fully.

This is basically how rotational molding has advanced over the past few years, from when it first started. There are many advantages and disadvantages of rotomolding, and it’s now widely used by different manufacturing companies today.


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