How to detect surface defects ?

When we think of measuring a wire or cable, we most often think of measuring its geometry, its electrical performance or its electrical insulation. However, its external appearance is also of real importance for technical or aesthetic reasons, such as color, roughness, uniformity, cracks; in other terms its surface aspect. Manufacturers of fine wires are particularly interested in coating or plating defects during the manufacturing process.

What solution for wire defects ?

Numerous devices on the market allow the geometrical defects of these wires/cables to be checked. However, when it comes to surface analysis, the choice is limited. And when it comes to analysing and detecting surface defects online such a lack of plating or scratches, solutions are scarce or quickly limited.

It is of course out of the question to use technologies that are intrusive or that could destroy the coating deposited on the wire/cable. Nor should techniques be used that can only be applied to samples offline. For post-production analysis, many technologies and measuring devices already exist. These include more or less advanced microscopes for surface characterization. However, it is still difficult to have an analysis of the entire surface and then it remains mainly an analysis of the section or a 2D view of the object being analysed. When it comes to measuring live during the manufacturing process, not all of these technologies can be applied. However, there are high-resolution cameras on the market for triangulation measurements of illuminated objects passing in front of them. However, they are limited for objects much larger than a millimetre and for rather slow speeds.

Surface quality measurement : CERSA MCI solution

The need to detect in-line surface defects on very fine wires during the wire drawing process is not new. This could make it possible to make corrections to the process in near-real time and therefore reduce the waste and rework.

CERSA, questioned many times for its experience on a solution capable of meeting this customer need, has been working with its R&D engineers for many years to come up with a truly innovative solution. Indeed, this device had to be able to detect continuously tiny defects on the whole circumference of fine wires on high speed lines. CERSA's answer is SQM (Surface Quality Measurement). After having undergone numerous validation tests at its customers' premises, it is now available on the market for the detection, analysis, characterization of surface defects of fine wires.

A patent technology which works like a ring camera around the circumference of the wire. A powerful real-time signal computing combined with fast sensors, analyse the surface and reconstruct the image of the surface, which is then displayed in 2D. Depending on the detection parameters set by the operator, alarms are generated when defects are considered to be faults. The image of the defect can then be displayed on the PC screen for further analysis. The CIM Prod software also offers many features for statistical analysis of defects.

A complete solution at the service of the customer for the continuous improvement of its manufacturing process.

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