Digital calipers are versatile dimensional measurement instruments used for inside, outside, and depth measurements. Calibration verifies accuracy across the full measurement range using certified gage blocks. Regular calibration ensures reliable measurements for quality control and manufacturing applications.
Inspect the caliper for physical damage, worn jaws, corroded surfaces, or illegible markings. Verify the display functions correctly and the battery has adequate charge. Check that the slider moves freely without excessive play.
Close the jaws completely and verify the display reads zero. Clean the measuring faces with a lint-free cloth before closing. If the caliper has a zero-set button, do not use it during calibration — the as-found reading must be recorded.
Measure a minimum of five certified gage blocks spanning the caliper's range (e.g., 25 mm, 50 mm, 100 mm, 150 mm, and the maximum range). Record the displayed value for each gage block and calculate the error at each point.
Using a calibrated ring gage or inside gage block holder, verify inside measurement accuracy at a minimum of three points. Compare displayed values to the certified reference values and record deviations.
Using a depth gage setting standard or gage blocks on a surface plate, verify the depth rod accuracy at a minimum of three points. Record displayed values and calculate errors.
Select one gage block near the midpoint of the range. Take ten consecutive measurements, recording each value. Calculate the standard deviation to assess repeatability of the instrument.
Record all as-found and as-left data on the calibration certificate. Apply a calibration label with the date, due date, and technician ID. If the caliper fails acceptance criteria, segregate and mark it as out of tolerance.
Error at any test point must not exceed ±0.02 mm (±0.001 in) for standard calipers, or per the manufacturer's stated accuracy specification. Repeatability (standard deviation of ten readings) must not exceed one-half the resolution.
12 months
Most quality systems require annual calibration (12 months). However, high-use environments or critical applications may require 6-month intervals. Your calibration interval should be based on historical performance data and risk assessment.
You need a certified gage block set of Grade 0 or better. Select blocks that span the full measurement range of the caliper, typically at five or more points including near-zero, midpoint, and maximum capacity.
Gage blocks are the primary standard for caliper calibration. While other certified reference standards can be used, gage blocks provide the best uncertainty and are required by most accredited procedures. Using uncertified references invalidates the calibration.
CalibrationOS tracks due dates, stores certificates, and generates audit-ready reports.
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