Definition of wheel gauge
The wheel gauge is also called the wet film wheel. It is composed of 3 equally spaced wheels coaxially. The middle one is slightly smaller than the outer wheel and is eccentric with a height difference. Hold the middle circle tightly with your thumb and forefinger. When the wheel gauge rolls on the wet film, you can read the thickness of the wet film from the position where the edge of the middle wheel just touches the surface of the wet film, corresponding to the scale on the outer wheel.
Measuring method of wheel rail
(1) When using a wheel gauge to measure the wet film thickness, place the wheel gauge vertically on the surface of the paint film so that the maximum scale of the two outer wheels touches the substrate to ensure that the wheel rail does not shake, thereby ensuring accurate measurement values.
(2) Roll the wheel 180° along the surface and check where the middle rim first contacts the wet film surface. The calibrated scale will indicate the wet film thickness at this point.
Note that when the wheel gauge rolls on the coating surface, it is better to start from the place with the largest gap, so that the wet film will not be pushed and squeezed, and the wet film thickness measured by the wheel rail is more accurate.
The results of the wheel-rail measurement indicate that at least two readings should be taken in the same way at different positions, so as to obtain a representative measurement result. The wheel-rail is generally expressed in μm, and reference can be made to GB/T 13452.2 for paints and varnishes Determination of film thickness related standards.
