A Wisconsin-based foundry came to Contact Rubber Corporation (CRC) with a premature belt edge wear problem.
Many CRC products are intended for use along with coated abrasive belts and bands. The support that the wheel gives the coated abrasive helps determine the grinding efficiency of the belt.
In a grinding application, when large amounts of material need to be efficiently removed, a coarse grit belt with a hard serrated contact wheel is typically used. The minimal resiliency of hard rubber along with the increased unit pressure created with the serration, allows the abrasive belt to rapidly remove stock as the wheels is rotated at a high RPM. Grey iron and aluminum foundries are an example of where this type of application is found.
One of the problems with aggressive off hand grinding is that the edges of the abrasive belt will wear prematurely. This occurs because grinder operators tend to use the edges of the belt more than the entire belt width in their grinding efforts.
The serration in the rubber covering helps create most of the unit pressure that is required for fast stock removal, and since the operator is using the edges of the belt more often than the entire width of the belt, the belt edge will wear at a faster rate than will the center of the belt.
Design a contact wheel which will give the abrasive belt the necessary support for aggressive stock removal, yet at the same time minimize edge wear on the belt edges.
The result of our efforts and experimentation was the development of the J72 serration. We are able to serrate the middle three quarters of the face of a contact wheel and leave an area of about 1/4 inch wide on both edges of the face without any serration!
By eliminating the serration on the edges of the wheel, the unit pressure exerted against the belt is minimized and edge wear on the belt is significantly reduced.