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Low-Pressure Microcellular Foam Lightens Load in EV Batteries

Korean molding machine builder Woojin uses nitrogen gas pressure as low as 70 bar with a glass-fiber-reinforced polyamide to mold EV battery holders that are 20% lighter than conventional components.

Stephen Moore

March 30, 2023

1 Min Read
EV battery cell holder
Stephen Moore

The recent Koplas Show in Seoul featured a number of injection molding innovations from machine builders, among them a low-pressure physical blowing process that demonstrated molding of an electric vehicle (EV) battery cell holder from a 40% glass-fiber-reinforced grade of polyamide (PA) 6. According to Joo In Chan, a staff member of the overseas sales team at Woojin PLAIMM, gas pressure as low as 70 bar (7 MPa) is sufficient when molding the 1,365-gram battery cell holder. It is 20% lighter than a non-blown equivalent component, while also exhibiting higher rigidity and no sink marks. “Competing processes can use pressures up to 200 bar,” said Jo.

The part was molded live on a DL500A5 (Super-Foam) machine with a clamping force of 500 tonnes in a cycle time of 210 seconds. Eight such EV battery cell holders are required for a single battery module.

Woojin’s foam molding technology can be applied to TPU and PVC midsoles.

The Super-Foam was also demoed by a second machine at Koplas, this time a 75-tonne vertical press with side injection that was molding midsoles from a thermoplastic polyurethane. Due to the extended cooling time requirement of 250 seconds, the SFV2400 (Super-Foam) press was outfitted with five molds on the turntable to maximize production efficiency.

Foaming ratios of up to 33% are possible, reducing midsole weight from 60 to 40 grams. Woojin reportedly cooperated with adidas on the project.

About the Author(s)

Stephen Moore

Stephen has been with PlasticsToday and its preceding publications Modern Plastics and Injection Molding since 1992, throughout this time based in the Asia Pacific region, including stints in Japan, Australia, and his current location Singapore. His current beat focuses on automotive. Stephen is an avid folding bicycle rider, often taking his bike on overseas business trips, and is a proud dachshund owner.

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