Robotic Rotational Molding Creates New Opportunities for Military and Aerospace Applications

April 1, 2023

Innovative robotic rotational molding technology allows for the use of new materials in manufacturing parts and hard cases for military and aerospace applications. This is creating opportunities for new product geometries, tighter tolerances, and less waste than traditional plastic molding.

There are thousands of applications within the aerospace and defense industries using plastic parts and storage containers. Today, the production of specialized parts and protective hard cases for military applications can call for unique materials to meet more stringent standards (flammability, high heat/cold tolerances, airtightness, watertightness, electromagnetic interference shielding, multi-layering, to name a few). Meeting these strict requirements can be challenging when using traditional molding processes such as rotational molding, thermoforming, blow molding, or injection molding.

In recent years, a growing number of companies have turned to robotics to enhance their manufacturing capabilities. In the world of specialty plastic molding, robotic rotational molding offers a new approach for designing custom parts and protective hard cases. This technology allows for precise control of multiple heating and cooling zones, customized material flow, optimized material use, increased product quality, consistent part traceability, instant cycle data collection, reduced cycle times, focused cycles for highly engineered resins, and elimination of labor-intensive processes.

Robotic rotational molding is enhancing the design and manufacture of premium hard cases for military and aerospace applications, such as this Gemstar Stronghold case. (Image: Gemstar Manufacturing)

Robomold robotic rotational molding is a leading-edge technology that is ideal for military, OEM, and aerospace applications where precision and repeatability are essential. This robotic rotational molding technology allows for tighter tolerances, which can be held with precision-distributed heat and material control for consistent part repeatability with optimized strength to weight ratios. It also allows for unsurpassed design flexibility, which includes the ability to layer different compounds and coatings into finished parts where conventional rotational molding cannot satisfactorily meet evolving design requirements.

Robomold technology is ideal for:

Creating unique product geometries
Meeting tight tolerances
Highly engineered resins
Producing lighter specialty components
Meeting reinforced mechanical properties
Meeting or exceeding MIL-STD 810F
Materials difficult for traditional molding methods
Preventing electromagnetic interference
Full automation manufacturing

Enhanced Process Control and Layering Materials

Robomold robotic rotational molding technology. (Image: Gemstar Manufacturing)

Many products need to withstand extreme temperatures out in the field. Traditionally, to meet those tolerances, manufacturers prefer metals such as aluminum or steel because of their heat resistance. However, there may be some applications where heat-resistant plastic, such as Polybenzimidazole (PBI), can match the performance of some metals, in terms of heat resistance, wear and tear, strength, and longevity. PBI is one of several high heat resistant plastics that lends itself well to robotic rotational molding. Robomold allows for more exact temperature control with numerous control zones used to reach the ideal temperatures needed.

Robomold allows the multi-layering of different materials with the ability to vary wall thickness throughout the part. (Image: Gemstar Manufacturing)

These zones can be adjusted throughout the cycle and are strategically placed throughout the tool. Our engineers can adjust process parameters with real-time data to ensure the product meets customer requirements.

For example, our company has partnered to design duct work parts for military vehicles. With Robomold, we can use a new, heat resistant material, which offers high flexibility for vehicle assembly. This same part would be very difficult to manufacture using traditional molding processes.

One of the key advantages of robotic rotational molding is the ability to easily layer different materials to obtain a desired specification. To clarify, it’s not that you can’t use the same materials in traditional rotational molding. It’s that some materials are better suited for robotic rotational molding because of its unique ability to control heating and cooling by zones. The application of controlled heat is much more difficult to achieve in traditional manufacturing processes.

For example, robotic rotational molding allows for the design and manufacturing of a three-layer protective hard case with EMI shielding requirements. Prior to this, the most common option for EMI-shielded cases was a heavy, easily dented metal case. Robotic rotational molding eliminates the metal and allows for a layer of EMI shielding material to be sandwiched between the layers of plastic to obtain the same shielding effectiveness while reducing the weight of the hard case.

In one recent partnership with NuWaves Engineering that shows an example of using robotic rotational molding to meet military aerospace applications, Gemstar teamed with parts distributor The Case-Center to develop a new protective hard case for U.S. Navy helicopters. NuWaves Engineering received a project to create a rotationally molded, double-walled, electromagnetic interference-shielded case for the U.S. Navy to house the Shipboard and Rotary Wing Tracking Unit in a tight space on the aircraft. The telemetry unit is responsible for relaying sensitive information such as GPS coordinates. A case that can prevent electromagnetic interference (EMI) was required in order to maintain the integrity of the data.

Beyond meeting a tight space, the case had to meet several other design requirements, including:

The hardcase must prevent all forms of EMI
The surface of the case must allow for the use of electronics immediately outside the hard case
The handle on the case must meet a military standard handle test for freefall hanging
The hardcase must pass the IP67 splash test
The use of hardware (handles, hinges, latches, etc.) must be salt resistant
The case must include internal cooling vents within the flange area

With these stringent specifications in mind, the Gemstar team recommended customizing a Stronghold case for this project. Stronghold double-walled cases boast GSR high-performance resin, patented latches, rubberized spring-loaded handles, recessed hardware, and interlocking stackability. This military-grade hardcase is designed and tested to meet or exceed MIL-STD 810F and military Long Life Reusuable Case (LLRC) standards.

“This case needed to fit behind the pilot’s seat in Navy helicopters,” said Barry Birkholz, Director of Technology Packaging at Gemstar.

“Using the Stronghold as a base, our engineering team further enhanced it to meet the Navy’s specs,” Birkholz added. “For example, they developed a waffle pattern on both the top and bottom of the case to dissipate heat. They used a cut-and-weld rapid prototype to verify fit and overall dimensions, as part of the engineering process.”

Within just 18 months, NuWaves Engineering, The Case-Center, and Gemstar developed a new EMI-shielded case to replace a metal container in U.S. Navy helicopters. Together with NuWaves and The Case-Center, Gemstar developed a hard case solution that the U.S. Navy has implemented on more than 200 aircraft.

Going Green

Another key factor in deciding which molding process is right for your product is waste minimization. Certainly, all manufacturers want to reduce the amount of material they use in the manufacturing process, both from a cost and environmental perspective. Because robotic rotational molding optimizes the amount of material needed to manufacture a part or case, the amount of scrap is dramatically reduced. More accurate molding means fewer product defects. In addition, robotic rotational molding will reduce cycle time and changeovers. All these reductions add up to a more consistent process and may help some organizations meet their environmental, social and governance (ESG) commitments.

Figure 1. Comparison between a part made with Robomold robotic rotational molding (left) and the same product made with conventional molding (right). (Image: Gemstar Manufacturing)

Because the manufacturing process is fully automated and involves a six-axis robot, Robomold will increase product consistency and quality. Figure 1 offers an example between the manufacturing of a fuel tank using robotic rotational molding (left side) compared to Conventional rotational molding (right). This part demonstrates there may be some products for which robotic rotational molding offers a better solution in comparison.

Meeting Standards

The military and aerospace industries need millions of specialty components and storage units to protect sensitive assets. While there are many efficient and proven techniques to manufacture these parts and products, there is now another manufacturing option design engineers can consider in helping them achieve their desired finished product. Robotic rotational molding allows for new materials and designs to be incorporated into product development not achievable with other types of molding processes. This new technology increases the range of product geometries, as well as environmental tolerances. Overall, Robomold robotic rotational molding technology has brought a new way of thinking to our design team as we approach solutions to customer challenges.

This article was written by Corey Latuff, Engineering Manager, Gemstar Manufacturing (Cannon Falls, MN). For more information, visit here .