SURFACE FINISH GAGE INDEXES AND MEASURES MULTIPLE PARTS

Mahr Federal offers a new surface finish gage, custom designed to index and measure multiple small parts, such as gears, fuel injector components, or inner and outer bearing components. Utilizing a lazy susan type staging table with customized tooling to accommodate up to eight measuring stations, the gage incorporates a Perthometer M1 or M2 surface measuring instrument, and supports most common DIN, ISO, ASME and SEP profile parameters, including Ra, Rz, Rmax, RPc. "With most surface measuring systems, the concept is to fix the part and maneuver the measuring head around it," said Ron Lavoie, Director Engineered Solutions for Mahr Federal.

"What's interesting about this solution is that we have fixed the measuring device and present the parts to it. This provides a very economical way to measure many different characteristics on a series of parts without having to replicate the measuring system." The initial gage design was for a customer that wanted a surface finish gaging station that would accommodate a series of different types of gears, each of which needed to be measured on the inside diameter and on the end face. "The fixture we designed uses a lazy susan type staging table to stage up to three varieties of different parts," said, a Mahr Federal product engineer and chief designer of the gage. "The part tooling holds the parts either on their IDs at two different measurement depths or on their end faces so you can measure the front face. The tooling is designed at a known height so that the measurement altitude is always the same. In operation, you put the part on the gage, rotate the table to index over to the centerline of the gage head, then rotate the handle to position the probe for measuring."

The compact bench-type gage is approximately 18 in long by 12 in deep and fully self-contained. The drive unit and measurement head are enclosed and completely protected from both the environment and mechanical damage. The highly sensitive diamond stylus probe is housed in a metal shroud and engaged by means of a proprietary probe retraction mechanism that ensures that the probe only contacts the part when it is in the proper position and ready to measure. "The system also eliminates the need to rely on some feature of the part to activate probe retraction as happens with other systems," said Toffling. "The probe is automatically lowered and raised when the measurement head is positioned on the part." The need for system calibration was also incorporated into the gage design. One fixture is equipped with a calibration standard that has three separate roughness standards.

In the current design, one coarse standard allows the operator to set the gain or amplitude of the instrument; a very fine standard checks the condition of the stylus; and a third standard checks system linearity. Said Toffling, "The only thing the operator has to do is rotate the table, index the measurement head to the calibration standard, and press the start button. Everything else is automatic. All the other positioning is automatic. So it saves time in calibration, and also, all the calibration certificates are right on the standards so there's no guessing what the values are." "The system has been designed to be as easy to operate and maintain as possible," said Lavoie. "All the fixture tooling and the staging table itself are machined out of DuPont Delrin®, which is very stable, doesn't corrode, and won't mar the parts. Table set-up is simple, too, with simple bolts for adjusting each fixture mounted. Yet the result is a highly sophisticated device that provides a precision platform for fast, accurate surface measurement on a variety of parts in a production setting."www.mahr.com