Oct 01, 2023

Robotic Rotational Molding Creates New Opportunities

Plastic products are used in more applications today than ever, and as their use continues to grow, so does the technology needed to develop competent solutions. Plastics manufacturers are being constantly challenged to find more innovative manufacturing processes to meet the growing demands of industry, both now and for the future.

Evolving standards related to flammability, permeability, extreme temperatures, and air and water tightness mean that plastics manufacturers must push beyond traditional molding processes such as rotational molding, thermoforming, blow molding or injection molding to find solutions.

One emerging solution is robotic rotational molding. Rather than traditional oven heating, this technology uses molds incorporating internal heating elements allowing for precise control of multiple heating and cooling zones. Further advancement comes with increasing the rotation to six axes. Not only is there greater range of motion, but speed and duration of each axis of rotation can be independently controlled.

The advantages are numerous and include more uniform material distribution, customized material flow, optimal material use, improved and more consistent product quality, reduced cycle times and elimination of labor-intensive processes.

Robomold robotic rotational molding is a leading-edge technology that is optimal for military, OEM and aerospace applications where precision and repeatability are essential. Robotic rotational molding technology allows for unsurpassed design advantages, including unique geometries and the ability to layer multiple compounds in a way that surpasses conventional rotational molding.

Robomold technology is ideal for:

Some products, such as fuel or liquid storage tanks (alcohol, hydrogen, gasoline and propane) and vehicle duct systems, need to withstand extreme temperatures while in use. To meet that requirement, manufacturers have traditionally avoided lightweight plastics in favor of metals, such as aluminum or steel, because of the heat resistance they offer.

However, the advancement of robotic rotational molding has enabled a shift in the marketplace toward the use of new specialized plastic resins and specific heat-resistant materials, such as Polybenzimidazole (PBI), which can match the performance of some metals in terms of heat resistance, wear and tear, strength and longevity.

Another example is Hostaform POM RF Polyacetal Copolymer (acetal), a material that is widely used to manufacture fuel tank components for a variety of applications (lawn mowers, snowblowers, boats, ATVs, etc.). Identical to acetal grades used in injection molding, Hostaform POM RF delivers outstanding moisture, fuel, solvent and alkali resistance, dimensional stability, durability and rigidity.

Hostaform POM RF and PBI are two of several specialized plastics that lend themselves well in conjunction with the precise temperature control and increased rotational capabilities of robotic rotational molding. The heating zones are strategically placed throughout the tool and can be adjusted throughout the cycle for optimal performance. Engineers can adjust all parameters based on real-time data to ensure the best product possible.

The combination of optimal material, state-of-the-art robotic rotational technology, and precision temperature control means that we can achieve consistent part-to-part repeatability with optimized strength-to-weight ratios.

In addition to achieving higher levels of product consistency, robotic rotational molding also allows for unsurpassed design flexibility.

Although the same materials can be used in traditional rotational molding, materials such as Hostaform POM RF are better suited for robotic rotational molding because of the robotic technology’s dynamic ability to pinpoint precise temperatures at critical locations within the tool during the manufacturing process. The application of controlled heat is much more difficult to achieve in traditional manufacturing processes.

More design flexibility allows unique geometries and higher-definition features than are possible traditionally. It also enables features such as high-adhesion inserts. In combination with unique materials, one can generate higher stiffness and heat deflection temperatures than polyethylene and some nylons, which opens new design possibilities in products like pressurized vessels. One emerging application is layering multiple materials presenting different properties (i.e., a low-permeability layer inside a high-impact resistance layer).

Because the manufacturing process is fully automated, Robomold increases product consistency and quality. The image above offers a stark example between the manufacturing of a fuel tank using robotic rotational molding with innovative resins compared to conventional rotational molding with traditional materials. This part demonstrates there may be some products for which robotic rotational molding (and certain types of materials) offers a better solution.

While there are many efficient and proven techniques to manufacture parts, such as liquid storage vessels, there is now another manufacturing option design engineers can consider in helping achieve their desired finished product. Robotic rotational molding technology increases the range of product geometries as well as environmental tolerances. Overall, Robomold robotic rotational molding technology has enabled fresh thinking from our design team as we develop new solutions to meet tomorrow’s manufacturing challenges.

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Kevin Paulson