What problems should be paid attention to in the calibration of coating thickness gauge?
1. Proper calibration is critical for accurate measurements. For calibration, a sample similar to the object to be measured is used, ie at the same time, the standard sample and the object to be measured should have the same shape and geometry. Basically, the more the standard specimens of the measurement objects are matched, the more accurate the measurement results will be.
2. Confirm that the following properties of the calibration sample and the object to be measured match: --the radius of curvature of the surface --substrate material (such as magnetic permeability, conductance; ideally, the standard sample and the measurement object should be the same material) --Substrate Thickness--Size of the measurement area
3. Before starting the calibration, make sure the calibration points, sensor tip and calibration template are clean. If necessary, remove any buildup such as grease, metal shavings, etc. Any impurities may affect the calibration and cause the calibration to be unstable.
4. Make sure to always find the same calibration position, especially the measurement of small parts and the measurement of edges and corners. For small parts it is recommended to use a measuring stand.
5. If using calibration foils, make sure they are placed in a flat position on the substrate material. Air gaps under the foil must be avoided as this will lead to erratic readings. In case of curved aluminum foil, make sure they are placed on the substrate as shown below.
6. Precision thickness standards must be handled with care. Any wear and tear on the thickness standards will be reflected in incorrect calibration values. Do not fold the calibration foil. Any buckling will cause an air gap under the foil, resulting in erratic readings. Keep the thickness standard clean. Any grease, oil, dust or other buildup must be avoided. A buildup of aluminum foil will be considered thickness and will result in a measurement error of the same value as the thickness of the buildup. To give you a general idea: the accumulation of a fingerprint is enough to cause a few microns of additional thickness error.
7. Keep away from strong magnetic fields during calibration.
8. More calibration standard thicknesses that can match the expected thickness will make the calibration and measurement more accurate.
9. According to the electromagnetic induction method, measuring the thickness of the non-ferrous metal coating on the steel or iron substrate requires multi-point correction. The thickness standard must be made of the same metal as the object to be measured later.
