The measurement methods of coating thickness in pre painted steel sheet mainly include wedge method, thickness difference measurement method, weighing method, X-ray fluorescence method, β-ray reflection method, magnetic measurement, eddy current measurement method and son on.
In national standard, the magnetic thickness tester belongs to magnetic measurement method, the drilling damage microscopic observation method belongs to wedge method, the metallographic microscopy method is arbitration test method and micrometer method belongs to thickness difference measurement method. Thereinto, micrometer method is also the common used method to measure the coating thickness of pre painted steel sheet in CAMELSTEEL.
At present, the most accurate and convenient way to measure the coating thickness is the equipment that hang the magnetic measurement and eddy current measurement together. The total thickness of the coating and the thickness of the cladding material were measured by combining probes at the same time.
Then the thickness of the coating was calculated. This measurement method is determined by the total coating thickness and cladding material thickness of the same point, thus avoids the influence of the cladding material fluctuation caused by the magnetic thickness tester, then the accuracy of the results have been significantly improved.