The bottom line
Most “the gauge is broken” calls are misjudgements. Following the order coupling to surface to settings to part to gauge locates the problem within minutes.
Check order and judgement criteria
Breaking a “suspected fault” into items you can rule out one by one avoids mistaking an operating issue for hardware damage, and avoids letting a real gauge problem slip past the calibration cycle.
- Coupling and contact — re-apply couplant, is the probe face seated steadily. This solves most “no reading” cases and takes the least time, so it goes first.
- Surface state — scale, oil, uncured coating and rough faces all cause abnormal readings; magnetic/eddy models are especially sensitive to surface state.
- Settings — sound velocity, unit (μm / mil) and measurement mode match the current part? A wrong mode setting often looks much like hardware fault.
- Part and gauge — only when the first three are normal consider substrate difference or gauge state. Then verify with a foil; if out of tolerance, send for calibration or repair — do not open it yourself.
Paired with an instrument log (serial, calibration date, certificate number, user), this order also feeds back criteria: if the same gauge keeps failing at step four, it is time to send it for calibration early rather than keep adjusting on site.
Frequently asked questions
My gauge shows no reading at all. What should I check first?
Check coupling and contact before anything else: re-apply couplant and confirm the probe face is seated steadily on the surface. This fixes most “no reading” cases and costs the least time, which is why it always goes first in the check order.
Readings keep jumping around. Is the gauge faulty?
Usually not. For magnetic and eddy-current models, jumpy readings most often come from surface state — scale, oil, uncured coating or a rough face. Clean and prepare the surface first; only if the instability persists after the surface is confirmed good should you suspect the gauge.
What settings should I verify when a reading looks wrong?
Confirm three things match the current part: sound velocity, the unit (μm or mil), and the measurement mode. A wrong mode setting often looks almost identical to a hardware fault, so rule it out before sending the instrument away.
When is it time to send the gauge for calibration or repair?
Only after the first three checks — coupling, surface and settings — are all normal should you consider substrate difference or gauge state. Verify with a foil; if the result is out of tolerance, send it for calibration or repair. Do not open the instrument yourself.
Why keep an instrument log?
A log recording serial number, calibration date, certificate number and user turns the check order into a decision tool: if the same gauge keeps failing at the final step, send it for calibration early instead of adjusting on site again and again.
Related instruments: DONGRU DR-A5 Automotive Paint Thickness Gauge · Request a quote