Accuracy and Calibration of Digital, Dial, and Vernier Calipers
• Based on ANSI ASME B89.1.14-2018, covering metrological characteristics of calipers.
• Partial surface contact error (E) and scale shift error (S) are key metrological characteristics.
• ASME B89.1.14 standard provides default specifications for E and S errors, which are the maximum permissible errors (MPE).
• Specifications are a function of the measured length, L, not the overall measuring range of the caliper.
• Calibration and verification of calipers are crucial to ensure accuracy.
• Conformance verification tests for EMPE and SMPE are outlined in ASME B89.1.14.
• Reference standard for inside measurements is typically a caliper checker, ring gage, or gage blocks and accessories.
• ASME B89.1.14 requires an additional test using a 0.2 in diameter ring gage for all calipers with measuring ranges up to 12 in (300 mm).