Ada zct auto [11/40] Zct auto

MEASUREMENT FOUNDATION

ZCT AUTO

10. Notice for instrument use

The main factors which have impact on the measuring accuracy of the instrument: the metal magnetic prop-

erty of basal body, the thickness of basal body, edge effect, curvature, surface roughness degree, external

magnetic eld, attached materials, the pressure of measuring head, the position of measuring head, deforma-

tion of test piece and so on.

1. THE FACTORS WHICH AFFECT MEASURING ACCURACY AND RELEVANT INSTRUCTIONS

1) The metal magnetic property of basal body

The thickness measurement by magnetic property method is affected by the change of metal magnetic property of basal

body. (In practical applications, the change of magnetic property of low-carbon steel can be considered as minor). In order

to avoid the effect of heat treatment and cold working factors, standard piece with the same property as the basal body metal

of test piece should be used to calibrate instrument. The test piece which is about to be coated can also be used to calibrate

instrument.

2) The thickness of basal body mental

Each instrument has a critical thickness of basal body metal. If the thickness of basal body metal is greater than the critical

thickness, measurement will not be affected by the thickness of basal body metal. The critical thickness value of this instru-

ment is 0.5mm.

3) Edge effect

The instrument is sensitive to the sudden change of surface shape of test piece. Therefore, it is not reliable to measure near

the edge of test piece or the internal corner.