Greifensee, Switzerland--Manufacturers around the world rely on scales to make certain their products meet stringent international standards when it comes to weights and measures. Mettler-Toledo's newest scale, the 8270 Series, provides such assurance.
Bumper guards under the platter help keep the scales protected from heavy loads dropped onto the units. They also remove static charges (ESD) that can build up on the platter and damage the scales or cause discomfort for the operator.
Searching for lower-cost bumper guards led Mettler-Toledo to an engineering team at RTP Co. (Winona, MN). Hoping to replace transfer-molded rubber for the bumpers while maintaining ESD protection, the companies joined forces to develop a special compound based on a styrenic thermoplastic elastomer (TPE).
The compound offers elasticity similar to the rubber it replaced, having a Shore Hardness of 60-70A. Volume resistivity of 100 ohm-cm, plus surface resistivity of 1,000 ohms/sq, provide the ESD protection needed for the application.
"We were looking for a less expensive material and process that offered equivalent Shore A hardness and static removal properties," says Mettler-Toledo's Jeff Preston. "We found it in the special material compounded at RTP."
Acrotech Southeast Inc. (Spartanburg, SC) injection molds the guards. "We tried to formulate something ourselves with carbon black," explains Rodney McGill, Aerotech's customer service manager. "What a mess. It was easier to let the experts at RTP compound the material for us--it's what they do best."