Coating thickness gauge

Abstract

In order to control organic coating thickness on steel sheet, two types of coating thickness gauges using a new method and the Brewster angle method has been developed for on-line monitoring . The new gauge has an on-line accuracy of +O.2um and the Brewster angle method gauge has an on-line accuracy of A portable oil thickness gauge has been also developed to measure the oil thickness easily in various 2 . INTRODUCTION Some kinds of organic coated steel sheet are widely produced for electrical appliances and automobiles.The coating thickness is one of the important qualities which determines the weldability ,corrosion resistance , and so on. In order to control the coating thickness less than 2um, two types of infrared coating thickness gauges have been developed for on-line coating thickness monitoring. When the infrared ray is applied to the coating film, the ray is absorbed within the coating film. The coating thickness is therefore measured using reflected intensity. However, the reflected ray is affected by not only the absorption but also the interference effect and a pass line variation. In this case, the interference effect occurs because of multiple reflections on air-film and film-steel interfaces. As there are several types of substrate with different surface roughness and reflectance, the degree of interference effect is different. The relative distance between the gauge and steel sheet changes while the steel sheet is moving. The degree of the change in the distance depends on the coating line where the gauge is installed. In the case of large pass line variation, a new method, called the four wavelength method, has be developed and in the case of strong interference effect ,the Brewster angle method1' was adopted.Demand for oil film thickness control has risen recently. So a portable oil thickness gauge using the Brewster angle method has been developed in order to measure the thickness of oil film easily in various places, for example, to adjust the oil coating machine. FOUR WAVELENGTH METHOD .PrincipleThe intensity of infrared ray which is transmitted through a film and at a wavelength equal to the absorption band of the film is given as: aL=log (1) where It denotes transmitted intensity, Ii denotes incident intensity, L denotes film thickness, and a denotes absorptivity. A reflected intensity spectrum of a coated O-8194-0668-6/91/$4.OO SPIE Vol. 1540 Infrared Technology XVII (1991) / 709 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/15/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

Parameter Settings for an Automated Gantry-Robot Painting System using a 3-Gun Atomization Spray Method for an Anti- Static Coating Process

“…Figure 15 shows samples of spray coupon thickness measured and marking process. All thicknesses were measured by an Elcometer (Honda and Matsui, 1991) and recorded. The non-destructive coating thickness measurements can be taken on either magnetic steel surfaces or non-magnetic metal surfaces such as stainless steel or aluminum.…”