Grinding Supports Gage Precision

Manufacturers worldwide depend on pin gages from Meyer Gage Inc. (S. Windsor, CT) to verify the quality of their parts. To maintain its competitive edge, Meyer has recently transitioned from laborintensive production to more automated processes. The update includes two centerless grinders, which are used for finishing operations on standard gage pins in diameters from 0.061 to 1.020'' (1.55-25.9-mm) diam in 0.1'' (2.54-mm) increments.

Pin gages are precision metal plugs used to determine the acceptability of diameters and depths of drilled or machined holes, for checking hole location and distance, and as masters to calibrate measuring equipment. Because they are used as standards, the gages must be manufactured to exacting tolerances. Depending upon the class, gage pins may have a tolerance of from 0.0002'' (5

Considering the different pin tolerance classes, English and metric dimensions, and various pin combinations, Meyer offers some 90 different pin gage sets consisting of hundreds of part numbers. It can take weeks to manufacture all of the part numbers in a given set, so batches of up to 20,000 pieces of an individual pins are processed at a time.

All the pins are manufactured using a through-feed centerless grinding operation. The parts start as a long 52100 alloy steel bar that is cut into 2'' (51-mm) lengths. After deburring and heat treating, pins are rough ground to bring them closer to size. Finish grinding takes place on one of two RK model 220-8 centerless grinders from Cincinnati Landis (Waynesboro, PA).

The finishing operation removes a maximum of 0.001'' (0.025 mm) of material. After surface grinding to smooth the pin ends, each pin is etched with size and serial number identification.

The centerless grinders have 20-hp (15-kW) main drive motors and are fitted with aluminum oxide grinding wheels. The machines use cam-type antifriction profile truing with a servomotor diamond axis.

"The ability of the RK centerless grinders to consistently hold roundness on these parts is a real benefit to us," says VP James Meyer. "That enables us to take a 0.0002'' tolerance Class ZZ gage pin and work the part down in a lapping machine to produce more precision parts such as Class X or XX pins."

Productivity at Meyer Gage has also improved. Each RK centerless grinder replaced two or three older non-CNC machines. Fewer through-feed passes are now required, stock removal is better, and geometry is improved with reduced wheel dressing frequency.

According to Meyer engineers, the machines' fixed grinding wheel position improves rigidity and speeds setups. An upper/lower slide arrangement under the regulating wheel and workrest requires only a single adjustment for rapid, accurate correction of taper or wheel contact. Circle 225

© 2005 Society of Manufacturing Engineers Provided by ProQuest LLC. All Rights Reserved.