Underhood metal-to-plastic conversions in the fast lane

Car design

Metal-to-plastic conversions for underhood applications continue to advance both for next-generation internal combustion engines (ICEs) and electrical vehicles (EVs). That was the message from Erico Spini, Global Marketing Manager for Radici Group’s Performance Plastics (Gandino, Italy). That’s not to say these conversions are without challenges, but Radici Group is making headway with engineering polymers that make these conversions possible, adding value and lightweighting benefits.

Spini gave his presentation, Car Parts Weight Reduction: Challenge of Metal Replacement for New Generation Engines, at the recent Plastics-in-Motion conference in Charlotte, NC. There are numerous applications for metal replacement in various underhood components using Radici Performance Plastics materials, mainly polyamide-based materials, Spini told PlasticsToday.

“The most important applications concern specific segments of the automotive industry, such as the powertrain and engine system, thermal management and chassis. In total, today about 15 kg of polyamide (PA) is used per vehicle,” he stated. “Considering all the polymers, we exceed 100 kg per vehicle.”

For example, Radici has experienced successful metal replacement with its standard grades in a battery support component using Radilon A RV500W 333 BK (PA 66-GF50 heat stabilized). According to Spini, this material provides excellent tensile strength at break, high modulus, and high fatigue and creep resistance. It also has excellent impact resistance with a continuous use temperature of 140oC, and offers a weight savings of 30%.

An oil circuit valve body assembly and elbow made from aluminum was replaced with Radilon S RV350W 339 BK (PA 6-GF35) to meet the following requirements: Withstand 1.2 million km traveling roughly the equivalent of 15,000 hours, exposure to 130oC in contact with air and motor oil while the components are subjected to pulsating pressure cycles (a total of 10 million). This metal replacement component also resulted in 30% weight savings.

For another component—an automotive chain guide rail (tensioner arm)— Radilon A RV500RW (PA 66-GF50) was used, resulting in a 23% weight savings. The metal part weighed 220 grams compared to 168 grams for the plastic part.

Spini noted that new-generation vehicles, hybrid and full-electric, must be lighter to increase the vehicle range, something that consumers want. “For this reason, an acceleration in the introduction of polymer solutions for engineering use is expected, including components such as the exterior panels, seat structure, housing for the protection of batteries and others,” Spini said.

“Plastic solutions are more environmentally friendly and meet European targets for achieving CO2 reduction,” said Spini. “As hybrid and electric vehicles become a mandatory choice, many lightweighting solutions for ICE components—including structural parts—can be translated to EVs using high-quality materials already developed for metal replacement projects.”

Spini pointed out several advantages of engineering polymers over metals, including the possibility of producing complex shapes for components that will be installed in small spaces (limiting degrees of freedom in design geometries).

Engineering plastics also help the EV industry address some challenges, both technical and economic. “For engineering polymers manufacturers, new challenges are opening up: Hybrid solutions with continuous fibers, flame-resistant materials and long-lasting insulators, materials suitable for bringing cooling liquids to the batteries in the presence of high power and very high safety standards.”

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