SHOP SOLUTIONS
Touch Probe’s 2-µm Accuracy Solves Part Measurement
A
complex component, incorporating four long slots among other features, was posing problems for Karl- heinz Lehmann GmbH. The solution was ultimately provided by a Cincom M32 lathe in conjunction with the TC76-Digilog touch probe from Blum-Novotest Inc. (Erlanger, KY). Ma- chining contractor Karlheinz Lehmann GmbH is based in Oberwolfach in Germany’s Black Forest. At its 1000 m2
site,
the family business employs 17 people, operating 20 state- of-the-art CNC lathes and milling machines, mostly in the manufacture of high-precision rotationally symmetrical parts. Lehmann employs state-of-the-art technology to manufac- ture small and large production runs in a three-shift opera- tion—though the night shift is unmanned. “Highly complex components are part and parcel of our business, but implementing a quick-coupler for com-
pressed air input was a tough nut to crack,” said CEO Timo Lehmann. The challenge was posed by a project for Parker Hannifi n GmbH, a world leader in drive and control technol- ogy and pneumatics. “The key components are hardened and coating-free cutting steel, threads, bores, and four lightly tapered slots. The slots were the crucial point of the whole design,” said Lehmann.
The parallelism of the slots was only allowed to vary by 2
µm from the reference values. Otherwise the fully automated machine, assembling the component unit at Parker-Hannifi n, would abruptly stop. Moreover, the quick-coupling would not work if the tolerance was exceeded. When assembled, the lightly tapered slots contain balls, which must not protrude too far, yet must also never be allowed to fall through the slot. Through this design, the Parker quick-couplers prevent the otherwise common snapping noise when detaching, and also allow single-hand operation. Just as challenging as the production process is the task of measuring the slots.
The TC76-Digilog touch probe can be positioned horizontally or vertically in the lathe depending on the measurement task.
The Blum TC76-Digilog touch probe proved the only
cost-effective means of verifying the design’s dimensional accuracy. The Blum TC76-Digilog touch probe at Lehmann is accurate to within 2 µm thanks to analog scanning. Analog measurement is always advantageous for assessing areas or lines. If a switching digital probe were to be used in the Lehmann application, for example, a very large number of points on the slots would have to be measured in order to attain an adequate resolution. By contrast, the TC76-Digilog scans across the surface at a measuring speed of 2 m/min. As this is happening, the system generates an extremely
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AdvancedManufacturing.org | April 2017
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