Posted On: Posted By:Rotomolding Tech.

Learn more about the Rotomolding Process.

Rotational Molding and Its Advantages

Rotational molding is a process used in the manufacturing industry to create highly durable and customizable hollow plastic products. The process allows for double wall construction. It ensures uniform wall fitness throughout the construction.

Rotational molding process is ideal for making large products such as tanks and bins that have to be hollow, and can be made in one piece. It is also utilized to make complex medical products, toys, recreational craft, and extremely artistic point-of-sale products.

In comparison with other methods of plastic molding, rotational molding has many advantages in terms of relatively low levels of residual stresses in the process and relatively inexpensive molds.

Rotational molding is also called roto-molding or roto-casting. Many manufacturers of hollow-type plastics usually prefer this method in making their products. Another process used in liquid-vinyl is slush molding, which is also a similar process.

Rotational Moulding process offers many advantages as compared to other methods of plastic molding such as injection molding, blow molding, and thermo-forming.

Benefits of Using Plastic

※ Plastic is corrosion resistant, it cannot rust. Stainless steel products are subject to rust in welded parts.

※Plastic is chemical resistant. It’s a material that can withstand various chemical components, which makes it perfect for tanks, intermediate bulk containers, and other containers.

※ Plastic is a durable material. It is extremely impact resistant and it does not dent. Plastic parts can incorporate metal inserts in high-stress areas as well.

※ It is economical. Plastic is lighter weight than metal, therefore it takes less fuel to operate equipment with plastic parts. The material is less expensive than metal. Because rotomolding allows for one-piece construction, this reduces assembly costs.

※ Plastic is a safe material to use. It eliminates sharp corners and burrs, resulting in a smooth, seamless product. This reduces the risk for injuries for operators.

Advantages of Rotational Molding Process

※Size Options:

Rotomolding can produce any size from the smallest part to larger sizes, which means the process is flexible compared to other systems. The process can be used on a small ping-pong ball sized plastic part to 21,000-gallon tanks. Many manufacturers are able to produce a large capacity tank between 0 to 1000 pounds, and as tall as 17 feet.

※Different Designs:

With rotomoulding, it is very easy to design different shapes. This is because when the hot plastic compounds are placed into a mold, they take the shape of the mold as they melt and then harden. The process makes it ideal for creativity since manufacturers can make any shape using the process. While other types of molding processes are inelastic in nature with few options, rotational moulding can provide different varieties of design in the manufacturing phase.


Rotational molding can easily accept metal inserts while producing the part. It also allows the possibility for additional threading inserts. Other methods are cumbersome, while with rotational molding can be processed at very low costs. Assembly techniques can be changed in the rotomoulding process easily. Other manufacturing methods do not readily take inserts and this can make it more costly than rotational molding.

※Color Sectioning:

Color sectioning is much easier with the rotomoulding process. Color blending can be done in-house to a variety of shades. Color matching is done easily on the process without extreme volumes. A number of colors can be achieved at a lower cost.

※Quality Surface Finishing:

Rotomolding process offers high quality surface finishing capabilities by taking the exact shape of the particular mold as well as the texture. This allows very high gloss quality finishes on the product surface. It can also produce smoothness and quality artistic design, and can take on a high oriental texture finish on its surface.

※Decorations in Mold:

The process takes any originally designed decorations made in the mold and will feature it on the plastic in a vibrant way. This amazing technique of in-mold graphics is used to decorate and design graphics are a by-product of rotational molding. The unique designs will stick permanently in the final plastic product. This method allows easy molding for items such as serial numbers, bar codes, and colorful logos. The designs often appear in better quality compared to the traditional ones.

※Quick Tooling:

The molding process uses low-pressure without any need of ejection or in-mold cooling, thus reducing the costs of a mold for rotational molding. Especially given the extreme heating and cooling cycles, aluminum manufactured molds tend to perform better. The process is cheaper when aluminum is involved. Depending on the design and complexity involved, a new tooling process can only take about four to twelve weeks.

※Top Quality Durability

Parts and cases that are rotomolded are stress-free and can withstand impact force, chemicals, and environmental factors. This is the reason why the process is ideal for making cases designed for both military and commercial use.

※Quick and Easy to Make and Customize:

Rotational Moulding can significantly reduce lead times. Molds can be made in a matter of weeks when possible.  The process allows for tooling to be produced which would mold multiple cavities of a product to be integrated into one mold, thus reducing the part price. Rotomoulding also allows further customization since the molding process is capable of using a wide range of materials.


Rotomoulding is a very inexpensive method to produce high quality products because of its speed and unique integration process. Larger products are to be molded at a lower cost than products made with other molding plastics processes. The cost of the equipment needed for rotational molding is also less expensive compared to other processes. With rotational molding, you get high quality products with superior durability at lower prices than plastics fabrication or even metal fabrications.

※Consistent Wall Thickness

Usually, metal components are weakest at the corners. These are the exact areas where the parts endure the most stress. With other processes of molding, it is difficult to achieve total consistency in wall thickness. With rotational moulding on the other hand, the constant rotation allows the polyethylene to coat every surface evenly.

Rotomolding Summary 

While not as widely utilized as injection molding or blow molding, the rotomoulding process has its place in each of our daily lives.  The durability of a rotationally molded product in comparison to an injection molded or blow molded product is second to none.  The low production requirements, inexpensive tooling costs and durability of the products help ensure that rotational molding is a plastics manufacturing process that will be around for generations to come.

Common Materials