On the conveyor belts of primary and secondary packaging machines for confectionery and baked goods (HFFS, FS, Thermoform or VFFS), sensors must reliably detect a wide range of products and films at all times. And the packaging machines must continue to work without interruption even if there is a change of product or packaging material.

Leuze has developed the DRT 25C dynamic reference diffuse sensor with a detection method for this area of application. This works with three light spots and a reference technology. The latter does not use the product as a reference, but the conveyor belt. To do this, the surface properties of the belt are first taught in. The sensor then recognizes all objects that do not correspond to the properties of the belt surface as "deviations". And it does this even if the conveyor belt is dirty or vibrating.

The belt surface is taught in via the teach button when the sensor is first set up. This eliminates set-up times when changing products and packaging materials. © Leuze

This method means that detection is completely independent of the surface properties of the products, such as color, gloss or transparency. With its three light beams, the DRT 25C detects the entire spectrum: small, flat, but also high and spherical products. It also detects irregular shapes and contours, even products with openings such as cookie crinkles. They are also reliably detected as a coherent part thanks to the wide scanning range.

The reliable detection of objects - even with difficult shapes and surfaces - guarantees a high machine throughput and avoids system downtimes. Even under difficult conditions such as vibrations or soiling of the conveyor belt.

The DRT 25C works with the belt surface as a dynamic reference for detecting objects. This means that the sensor detects all objects that do not correspond to the belt surface, even if the conveyor belt is dirty or vibrating. © Leuze

No adjustment work is required on the sensor when changing products or packaging materials. This shortens set-up times and enables higher production quantities. The DRT 25C is quickly set up thanks to automatic teach-in via its teach button. All that is required is a universal mounting position for all objects. Additional functions can be easily integrated into the machine control system via IO-Link. For example, a warning message in the event of excessive soiling, the use of the counter built into the sensor or the disabling of the teach button. as