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Automotive Supplier Scans Parts With Diamond Styli

Engineers are always pushing the limits of what is technically feasible, placing even more exacting demands on precision from one year to the next. This prompted the automotive supplier Pankl, whose portfolio includes connecting rods for race cars, to switch from discrete-point measurements to precise scanning. But since they were in constant contact with the workpieces being measured, the silicon nitride stylus tips were wearing down at a rate of up to one micrometer per day – too much to ensure the precision of the measurement results without additional testing. Thus Pankl requalified its scanning styli twice daily, and each time this meant the coordinate measuring machine was out of action for 15 minutes. Moreover, replacing an old stylus with a new one once per day was not an uncommon occurrence.

Diamonds For Scanning

Measuring a connecting rod with a diamond-coated stylus

Even though continually qualifying and changing the styli had become the norm over the years, Mario Pichler, Head of Strategic Metrology at Pankl Racing, thought this process was suboptimal. Hearing about new styli with a diamond coating from the field staff at ZEISS Industrial Metrology piqued Pichler’s interest and ordered a loaner stylus – initially the more expensive, solid-diamond version – for one of the two ZEISS PRISMO systems used for the final inspection of connecting rods. Pankl also started using one of the diamond-coated styli as well. An additional measuring machine for in-process checks was fitted with a solid-diamond stylus. However, for those process steps where no scans are performed, everything will stay just as it is for the time being.

Increased Measuring Machine Uptime

The company started using diamond stylus for the final inspection of all connecting rods for race car engines. A scan lasts three minutes and provides far more measurement values than with a discrete-point measurement, thereby increasing the reliability of the results. And how are the new styli holding up? After more than a year, Pichler reports: “We haven’t noticed any wear thus far.” This also means there is no longer any time-consuming qualification and no need to replace out unusable styli. Pichler reports that “switching to the diamond-coated and solid-diamond styli has definitely paid off.” This has got him thinking about the future: he is currently considering using these styli in the gearbox manufacturing area.

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