Redland bolsters production with sensor install

02 November 2009

Monier Redland has turned to Sick UK to boost product quality and minimise waste with laser sensor technology on a roofing tile line at its Leighton Buzzard, UK, plant. Sick DT50 sensors were chosen to accurately and consistently detect upper and lower fill levels in a hopper.

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 being maintained.”

Darren Pratt, product specialist for the SICK distance sensor products added: “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 five and ten times that of a photo-electric sensor. The DT50 has addressed this issue, providing a cost effective time of flight solution for such applications”

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