Heighten the senses

Laser sensors from SICK help Monier Redland maintain its tile consistency

Achieving consistent product quality with minimum waste is one of the key engineering challenges in roof tile manufacture. New laser sensor technology from SICK UK installed at Monier Redland's Leighton Buzzard plant is dramatically improving production efficiency on the roofing tile line.

The factory produces around 67,000 tiles in a 12 hour shift. The tiles are made from two concrete layers, a fine grade upper layer and a stronger lower layer.

Mixes for the layers are automatically fed into separate hoppers and extruded together onto a conveyor as one tile. The compaction of each layer is governed by the level of material in the hopper, so keeping the level of mix within tight upper and lower limits is essential. Having too much or too little compaction could reduce product quality, waste material or even result in product being scrapped.

"The SICK DT50 laser sensors are able to detect accurately and consistently the upper and lower fill levels, and signal the feeder to start or stop supply," explains shift electrician Simon Jackson. "The laser sensor signal is not affected by the mix colour or the dirty environment.

"We had constant problems with the photo-electric sensors we were using previously. Every time we changed products and colours, we had to recalibrate the sensors to monitor the level accurately. It took several iterations before we got it right, and could result in a lot of waste; although checking sensor operation used to take time, we always had to make sure it was correct to give us peace of mind.

"By contrast the SICK DT50s maintain their detection accuracy, despite changes to the product colour. We can now ensure consistent quality in our tile ranges, while reducing the cost of waste and rejects.
"We now have such faith in their reliability and accuracy that we now switch straight from one tile colour batch to another without any concerns. Redland has always had a high reputation for quality, and the new sensors give us added confidence that the consistency is "T being maintained."

Introduced in early 2009, the DT50's temperature-stable light spot and negligible black/white shift difference enable complete confidence in measurement precision
no matter what the colour of the surface. Initially designed as a low-cost distance measurement device with a range of up to 10m and repeatability of 2.5mm, the DT50 is often used in place of photo-electric proximity switches due to its long range and colour independence.

Easy to install, the DT50's site-proven, user-friendly intuitive set up and key operated menu can be navigated without the operating manual, allowing easy, on-site adjustment to suit working conditions and practices.

Darren Pratt, product specialist for the SICK distance sensor products comments: "This was an example of a photo-electric proximity sensor being used in an application to which it is not best suited due to technical limitations. Until the launch of the DT50, laser time of flight sensors offering adequate accuracy for this type of application cost between 5 and 10 times that of a photo-electric sensor. The DT50 has addressed this issue, providing a cost effective time of flight solution for such applications."

The DT50 is the latest product in a large range of distance sensors offered by SICK. "The SICK distance sensor portfolio is probably the widest offered by any manufacturer," adds Pratt, "with devices capable of delivering measurement accuracies to the micron for quality control applications to products with a measuring range of over 1.2 km for crane positioning applications plus many others devices in between."

For more information please contact SICK UK on tel: +44(0)1727 831121
or visit:

March 2010

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