Grinding Journal - Fall 2007 - (Page 8)

Tolerances down to 10 microns required a measuring machine with better than one micron repeatability TMMK’s regrind shop sharpens 120 tools per man per day, or close to 40,000 tools per month. About 8% are critical tools requiring 100% inspection: All the reamers and some of the drills. Put another way, the critical tools are those with tolerances of 100 microns or less. Most of TMMK’s reamers have a tolerance of 10 microns or less. Since the repeatability of the measuring method should be at least ten times better than the part tolerance, they needed a method with better than one micron repeatability. “We’ve got some reamers that we’ve tried to measure manually every now and again, like a three flute gun reamer. But we bring it here and the Helicheck measures consistently, much better than we can do by hand, just on account of the length. It’s about 230 mm long, so runout is a real concern and we can’t measure that manually” - Mike Crouch, Team Leader than we can do by hand, just on account of the length. It’s about 230 mm long, so runout is a real concern and we can’t measure that manually.” And it’s getting even harder TMMK usually measures lip height, runout of the OD, relief angle, and diameter, and the tools are not always easy to measure: single flute PCD reamers; 6, 8, and odd flute reamers, and so on. And Mike Johnson reports that “the designs are becoming more complex and the tolerances are tighter. We have tools coming in the new engine we have never run before that are very complex and that will cost more than our typical operations but they save money in another place by being able to combine operations and reduce capital equipment.” People tend to see what they expect to see, but the machine remains neutral There is a natural bias on the part of operators to measure a tool so that it meets the nominal value. continued on page 13 Team Leader Mike Crouch indicates the etching on the shank that identifies this reamer and ties it to the inspection report The Helicheck was their only option, as confirmed by Team Leader Mike Crouch, “We’ve got some reamers that we’ve tried to measure manually every now and again, like a three flute gun reamer. But we bring it here and the Helicheck measures consistently, much better Fall/Winter 2007

Table of Contents Feed for the Digital Edition of Grinding Journal - Fall 2007

Grinding Journal - Fall 2007 Contents From Virginia: Apparently no credit crunch for machine tools Why measure cutting tools Other perspectives on CNC tool measuring Productive grinding of superalloys SUPER service grinding BIG rolls Problem Solver

Grinding Journal - Fall 2007

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