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Rotomolds: A Design Guide

Categories: news

It is essential to employ an engineer who understands rotational molding and RotationalMolding Design Firm China when designing a tool or mold for a rotomolded part. Rotomolding can produce hollow parts and parts with double walls based on the mold design. Rotational molding can incorporate unique features into the details, such as molded threads, aluminum extrusions, fittings, or even carbon or stainless steel components such as structural tubing and stainless steel bushings. As rotomolding produces virtually stress-free products, it makes exceptionally durable products. It is possible to design products impervious to nature's elements if the proper materials are used, such as virgin polyethylene. Various industries can benefit from rotomolding.

Rotomolding: Designing for the process

Ideally, rotationally molded parts have seamless transitions between shapes or aspects of the design. The role may be strengthened by adding ribs, kiss-off points, and modifying angles and shapes to add rigidity and strength. You can maintain structures with foam by adding it to some designs. The rigidity of foam-filled parts is significantly increased and their tensile strength. As well as metal inserts, other metal components can also be molded into products for added strength, such as aluminum extrusions or stainless steel bushings. Several rotomolded products are available with spin weld fittings, graphics, bulkhead fittings, and more.

Designing Rotomolds to Avoid Issues

During the rotomolding design process, many design issues are revealed. Several design issues can be avoided or designed around with little direction or education on the front end, saving money on manufacturing or production costs later on. Here are some tips for avoiding some common problems associated with rotomolded designs.

Sharp Corners

Rotomolding produces sharp edges similar to other plastic production processes. In the design process of a rotomolding product, sharp corners should be avoided whenever possible. During the molding process, raw materials are prevented from flowing through sharp edges.

By adding a radius to a corner, many rotomolding designs can avoid sharp edges. In this way, the visual appeal of a rotational molding design will be enhanced.

Draft Angles

Rotomolded products must be designed with draft angles in mind. An angle's primary purpose is to help release the part from the mold as it cools. Simple geometric shapes like a cube, a block, or a vertical water tank don't require a supplemental draft, unlike geometric shapes with heavier textures or engraved details, like company logo designs.

Material Flow

Rotomolding design review often finds material bridging between wall surfaces. Consequently, the material will "bridge" or "web" between wall surfaces when there is not enough space between them for the material to flow.


Flat Walls

It isn't easy to achieve large or long flat surfaces with rotational molding. Rotational molding produces hollow parts with no internal structure since open structures are continuously formed. Any engineer with experience rotating parts knows that flat walls should be avoided or long flat surfaces need to be broken up with some geometry to give the piece some structure and minimize warpage.

Rotomolding Design

It's more convenient to design products and make the molds for rotomolding with rotomolding. During the rotational molding process, the molds or tooling can be modified after they are produced in case the product or tooling needs to be changed.



In rotomolding, shot weights can easily be adjusted by simply adding additional material to an existing shot weight without modifying the mold.