New Molding Process Recharges Surge Suppressor Housings

Switch to pre-colored vinyl generates better products, $100,000 savings

The Challenge

It was a manufacturing nightmare: for every 20 pieces that rolled off the assembly line in China, three had to be thrown away. It was costly and embarrassing for the injection molding contractor – particularly when it came to the attention of the OEM that was purchasing the housings for surge protectors they exported to the United States.

The housings were produced in white, blue and gray using flame-retardant natural acryonitrile-butadiene-styrene (FR ABS) with concentrated color additives. But when they came out of the mold, not only were 15 percent of the parts being scrapped, others failed to meet standards for color consistency and high-quality appearance.

The molder and OEM needed a new solution that would deliver consistent color and appearance with a substantially lower scrap rate.

The Solution

Looking to solve the problem together, the OEM and molding contractor turned to PolyOne’s operation in Dongguan, China and explained their requirements. 

Whichever polymer was selected had to achieve a UL 94 V-0 safety rating at 1.8 mm thickness or lower. It also had to have good impact resistance and be consistently colorable in white, blue and gray. Scrap rates needed to be a maximum of 5 percent. The molder also wanted to achieve a reduction in overall production costs.

Working together with these customers, the PolyOne team developed a solution that used a Geon ™ high-flow, high-impact rigid vinyl molding material with a proven history in electrical housing applications and a UL 94 V-0 rating at 1.4 mm. 

The molder found it could eliminate the problems with color consistency by ordering the material pre-colored to the manufacturer’s specifications. An economic analysis determined this approach also would reduce production costs compared with the use of FR ABS and added color concentrates.

Two concerns remained: The molder didn’t have experience using vinyl as a raw material, and it wasn’t prepared to take on the high cost of retooling for the new material. So the PolyOne team formulated the customized Geon vinyl in white, blue, and gray in a way that would require only minor modifications to the existing mold. 

The Impact

The material transition went smoothly and production quickly ramped up. By switching from FR ABS and color concentrates to pre-colored Geon vinyl, the electrical manufacturer saved $100,000 in operating costs and gained a number of manufacturing improvements:

•    Improved color consistency that met all of the manufacturers standards
•    Improved appearance in the finish of parts
•    Increased speed and efficiency
•    Greatly reduced scrap rates

The injection molding contractor is now working comfortably with a wider range of raw materials and is on firmer footing with its customer.