Abstract
The measurement of surface cleanliness is a significant problem in many industrial and technological processes. Existing methods are based on laboratory procedures, that are not performed in real time, can not be automated, and usually are restricted to a small portion of the sample. In this study we describe a new method for real time measurement of the amount of surface dirt or contamination deposited on a surface. It relies on the ablation of the surface dirt film by means of a short laser pulse, and the subsequent measurement of the emitted sound. The intensity of the sound is proportional to the amount of surface dirt and provides a direct measurement of the cleanliness of the surface. We also developed a reference sample for calibration, based on a uniform distribution of dots printed on white paper. The density and the dot size can be easily modified providing a homogeneous, uniform and reproducible standard for the measurement. Based on this method, we designed, developed and patented the first industrial instrument for on-line determination of the degree of cleanliness of manufactured cold rolled steel plate bobbins.
Highlights
Existing methods for surface cleanliness determination of dirt measurements are based, in most of the cases, on labora tory procedures, outside production fines [8,9], and in special cases they give adirect measurement [10]
The intensity of the sound is proportional to the amount of the measurement of the transparency of an adhesive tape that surface dirt and provides a direct measurement of the cleanli hasbeenstuckandremovedfromthesurfacetobetested(tape ness of the surface
All thesemethods have thefollowing drawbacks: they are not performed in real time, and are time consuming; they can not be automated, and usually they are restricted to a small portion of the sample
Summary
A B ST R A C T Themeasurementof surfacecleanliness is asignifi cant problem in many industrial and technological processes. The density and the dot size can be modified providing a homogeneous, uniform and reproducible standard for the measurement Based on this method, we designed, de veloped and patented the first industrial instrument for on-line determination of the degree of cleanliness of manufactured cold rolled steel plate bobbins. Different types of surface dirt were analyzed: dirt pro duced by hand-manipulation of plastic surfaces; residuals generatedduring manufacturing ofcold rolled steel plates and candle soot deposited on glass substrates For opaque samples, such as steel plates, conventional measurements were performed using the tape method. Since it is not possible to produce surface dirt with con trolled thickness, size and distribution of the particles that compose the dirt, we decided to develop reference samples These dirt references can be made by means of a sim ple computer program and a printer.
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