Quality Magazine - March 2009 - (Page 41) measurements for relatively small tolerance classes also is verified by the other shaft fits that were tested as seen in Table 1. Based on the fact that the triple standard uncertainty of the test equipment should only equal a maximum of 20% of the measuring tolerance (if T≤IT7), then the smallest testable diameter tolerances Tmin in the nominal dimensions range are the basis for the test plan. Figure 3 5 4 3 2 1 0 -1 -2 -3 -4 -5 20 40 60 80 Diameter [mm] 100 120 140 Diameter Deviation ADVANCED MEASURING UNCERTAINTY To ensure that correct test decisions are made at the tolerance limits, the advanced measuring uncertainty of the test process must be known. The usual variables that influence the length measurements—operation and temperature—can be almost totally ignored because the measurement is automated and the temperature differences resulting from the measurement deviations are largely compensated for, depending on operating conditions. Workpiece conditions that can cause measuring uncertainty during series measurements, such as the geometric Source: Hommel-Etamic America surface structure, form deviations and contamination, can lead to inner part control that equals the standard uncertainty of the object, uObject. The influence of form deviations and surface roughness when determining the diameter over the cylinder envelope lines also is largely reduced by the choice of the evaluation process. The diameter of the hard-turned bearing seats can, for example, be determined via the peakline of the surface profile and is recorded by the CCD line of the optical gage in high resolution. To determine the object dispersion, 50 measurements were taken from the bearing cylinder under repetitional conditions. The standard deviation, One controller for eight tools. Reduce your purchase, installation and operating costs while increasing your error-proofing! Control your process. Capture and document the torque data for up to eight tools in any combination. Cost-effective error-proofing for your threaded fasteners! The Global 8 Improve your quality and your profits! See it at www.srtorque.com! Quality Quick Clicks 416 at qualitymag.com www.qualitymag.com March 2009 | QUALITY 41 http://www.srtorque.com http://www.qualitymag.com http://www.qualitymag.com
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