Toughened PA 66 boasts low-temp impact strength and superior surface finish

Clariant (Muttenz, Switzerland) is supplying a special polyamide (PA) 66 compound for a molded power distribution box manufactured by GEP Power Products, Milwaukee, WI).

 GEP supplies standard and custom electrical components to leading manufacturers of trucks, buses and off-road vehicles including FreightLiner, Thomas, John Deere and International. GEP sought a plastic material with superior low-temperature impact resistance and durability, good dimensional stability and uniform surface finish for the application ion question. The material was supplied by Clariant Specialty Compounding (Holden, MA).

For this electrical fuse box, used on trucks, buses and off-road vehicles, GEP Power Products specified Clariant's Renol 6608LLT super-tough nylon 66.Normally installed on the underside of large commercial vehicles, a school bus in this case, the fuse box can be subject to extreme heat and cold, moisture and impact by road debris."We were trying to develop an enclosure to protect an electrical fuse block," explains Jacek "Jack" Korczynski, GEP's Vice President - Design Development. "Because this device is normally installed on the underside of large commercial vehicles, it can be subject to terrible abuse in extreme heat and cold. We test these boxes by freezing them to -40°C and firing ¾-inch rocks and gravel at them, so we knew we needed a really tough plastic and asked Clariant for their recommendation."

"The problem with most toughened nylons," says Robert Wick, Clariant Specialty Compounding Product Manager, "is that they tend to develop a swirled or mottled surface during the injection-molding process as a side-effect of the impact modifying additives. This would be unacceptable to GEP and so we suggested Renol 6608LLT, an impact-modified nylon 66 that is formulated to minimize that effect." 

Initial samples were a bit too flexible, Korczynski recalls, but this was overcome with some minor design changes that added stiffness and, today, after 18 months on the market, the GEP power-distribution box is meeting all performance expectations - even in off-road service on the frozen North Slope of Alaska. 
GEP grew out of Precision Cable Assemblies, which started in business some 30 years ago, producing wire and cable for the automotive and truck industry. GEP was formed about eight years ago to make and market other electrical products like the power-distribution box. "We cater to the mid-market," explains Rich Horky, President. "We're structured to deliver the customization and rapid-product development that larger competitors can't provide."