Gemstar Manufacturing’s proprietary technology enables production of fluorination-free containers.
CANNON FALLS, Minn.— Gemstar Manufacturing, an engineering-based manufacturer of hard cases and custom OEM parts, uses its proprietary, robotic rotomolding (rotational molding) technology to produce rotomolded fuel tanks made of acetal.
These rotomolded acetal fuel tanks “have been identified as a highly viable alternative to fluorinated fuel tanks,” following a decision by the U.S. Environmental Protection Agency (EPA) to halt production of fluorinated coatings for HDPE (high-density polyethylene) containers, Gemstar said in a company release.
The EPA made the decision to halt production of the fluorinated coatings due to contamination by PFAS (polyfluoroalkyl substances). But Gemstar offers what it called a “fluorination-free solution,” having commercialized multiple EPA-certified acetal fuel tanks made with its Robomold® robotic rotomolding process.
“Our innovative technology is a highly viable option that can fill the emerging needs of OEMs and molders who are struggling to fill production needs amidst disrupted supply chains,” said Kevin Lumberg, channel manager for Gemstar Manufacturing, in the release.
Gemstar’s exclusive Robomold technology is reported to provide tighter tolerance control, as precision-distributed heat and material control ensures consistent part repeatability and optimized strength-to-weight ratios. The technology is also said to allow for excellent design flexibility, including the ability to layer different compounds and coatings into finished parts. Rotomolded acetal fuel tanks provide single-layer barrier protection that meets EPA requirements in comparison to injection molded HDPE tanks that require fluorination, the company said in the release.
According to Gemstar, nylon 6 has historically been the only material option to achieve a permeation barrier with a single-layer rotomolding process. However, nylon 6 is difficult to rotomold and yields a high scrap rate and poor cosmetic appearance. In comparison, acetal delivers a single-layer structure that achieves permeation requirements and provides favorable processability, low scrap rates, and favorable cosmetics, the company said.
Acetal has previously been used in injection molded fuel tanks. However, material suppliers have developed new rotomolding grades that incorporate additive packages that raise the heat performance, according to the release.
Robomold’s computer-controlled technology reportedly allows for precise control of multiple heating and cooling zones, customized material flow, optimized material use, increased product quality, and part traceability. It also offers instant cycle data collection, reduced cycle times, focused cycles for highly engineered resins, and the elimination of labor-intensive processes, Gemstar said.
The core of the technology is a six-axis robot that is said to deliver a greater degree of rotation than traditional rotational molding. Instead of using a heating oven, the robot tumbles the electrically heated mold, which incorporates numerous separate heating zones. Applying direct heat to these zones enables plastic resin to reach its ideal processing temperature and permits manufacturers to create geometries that were previously unattainable, the company said.
Robomold is also reported to deliver a range of sustainability advantages versus conventional rotational molding. According to the release, robotic rotational molding reduces cycle time by 25 percent to 30 percent, with little to no scrap compared to traditional rotomolding. Researchers at Queens University Belfast recently reported that Robomold’s electrical mold heating method takes significantly less time to heat the mold compared with a conventional oven, saving more than nine minutes (22 percent) with no appreciable difference in part quality.
Gemstar said that as end-use requirements become more stringent, Robomold robotic rotational molding is also finding greater use in custom applications. The company described the process as “ideal for military, OEM, industrial, and commercial applications where precision and unsurpassed repeatability are required.”