Inductive proximity sensors from SICK are being used by a leading Swiss retailer to sort wooden and plastic pallets automatically at their warehouse.
The Migros Cooperative is a major wholesaler and retailer in Switzerland, functioning as the bridge between producers and consumers.
Every day, about 780 suppliers deliver goods to Migros, supplying the 700 branch stores with about 330,000 different articles on a daily basis, totalling up to approximately 7.6 million load devices that move back and forth between goods suppliers, distribution centres and stores.
Each day also sees the shipment of 4,500 to 5,500 wooden and plastic pallets with diverse articles to the branch stores.
Wooden pallets have been found to be susceptible to breakage and distortion, as well as water absorption that can make them weigh up to 40kg. Plastic pallets on the other hand, are lighter and more hygienic, and can be fitted optionally with two to six steel pipes for reinforcement.
Migros is currently testing plastic pallets made by the Swiss Utz Company for suitability in everyday use, which poses new challenges for the warehouse management as the plastic and wooden pallets must now be stored and entered separately.
According to Anton Loosli, Manager Maintenance Delta, a key objective was to separate the plastic pallets automatically and reliably from the wooden pallets but the demands on sensor technology were relatively high due to the harsh ambient conditions and limited installation options. Optical sensors were usable only to some extent and more susceptible to malfunctions.
The IQ40 inductive proximity sensors from SICK were selected for the application. Wired differently for the pallet separation, the inductive sensors featuring a sensing range of 35mm are installed between the transport rollers of the conveyor belt.
The IQ40 inductive proximity sensors detect the presence of nails in the bottom of the wooden pallets, actuating the transverse conveyor to sort them out. The compact, rectangular proximity sensor has increased sensing ranges and an active sensor surface that can be aligned in five directions.
The sensors can be quickly installed or replaced using the M12, 4-pin device plug.