Gloss rate sensors

The sensors of RLS-GD series are used for online measurement of gloss degree. In the production of plastic sheets (design sheets, wall coverings, floor coverings, table coatings, foam sheets, and coated carrier materials for the furniture industry, automobile industry, fashion industry, or construction industry) and ceramic parts (ceramic tiles and plates for wall and floor) 100% quality inspection of the optically visible surface has become an ever more frequent requirement. For this purpose the RLS-GD sensors feature non-contacting detection of the gloss degree. The simultaneous measurement of the object from two different directions (direct reflection and diffuse reflection) allows intensity-independent evaluation. The sensor can be taught to a certain surface, and up to 31 tolerance windows can be applied around the taught value. Measurement output is performed digitally by way of five outputs.

Application examples

Checking the presence of sub-decor during laminate flooring production

It may happen in the production of laminate flooring that the sub-decor is not applied. Such missing sub-decor should be detected as early as possible in the production process, which is why surface checking should be performed directly after the laminating unit. Because of the great variety of different products and surface decors, image processing systems and color sensors turned out to be unsuitable for this application. The RLS-GD-15/60° gloss sensor, however, can perfectly distinguish between sub-decor present / not present. The application uses the analog output (4mA ... 20mA), which behaves proportionally to the gloss grade of the surface. A missing sub-decor leads to a sudden change of the analog signal, i.e. of the gloss grade. It is furthermore possible to perform teaching to the respective sub-decor, the gloss grade is then indicated in 31 stages (from good to bad) by way of switching outputs, and can thus easily be interrogated by a PLC. When a certain stage is exceeded, an alarm signal can be triggered or, in case of small deviations (trend), the operator can be informed in time.

Online gloss measurement at laminate flooring (monitoring of counteracting paper)

These sensors are used to check whether the resistant hard-paper layer is applied correctly. For this inspection use is made of the different gloss degrees of the hard-paper layer and the uncoated back side of the laminate flooring. This wood processing company presently is considering the use of the RLS-GD-15/60° for quality inspection of the decor, where a distinction should be made between decor and subdecor.

Online gloss measurement during PVC-flooring production in transverse motion operation In the production of plastic floor coverings the gloss degree decisively depends on the material temperature in the extruder. Environmental influences such as air humidity and ambient temperature also are of importance with respect to the gloss degree.”Until now, measurements were only performed at the start and end of production. With the RLS-GD-15/60° online measuring system the gloss degree can now be determined during the whole production process.”It is furthermore planned to use the analog signal (4...20mA, proportional to the gloss degree) for automatically controlling the temperature of the extruder and thus the gloss degree.

Gloss measurement in the paper industry Since the gloss degree should be measured on both sides of the paper web, and the paper web should not bend during measurement, but should run flatly, the position for the RLS-GD-15/60° gloss sensors was chosen at two deflection rollers. In order to also obtain information about the gloss degree characteristics in crosswise direction of the paper web, three gloss sensors are mounted on each side (close to the left edge - center - close to the right edge). This means that there are six sensors for one system