Robust inductives ‘Turn-over an Old-leaf’

Agriculture is using increasingly complex automation in its machinery and an example is in composting machines. Contrinex’s uniquely robust V4A/ 316L stainless-steel sensors are relied upon for operating reliably in the challenging environment of the inside of the drive rotor. Withstanding dust, humidity and high temperatures, the sensors enable the machine to provide the fast drying of materials and optimal decomposition with reliable sanitisation being ensured.

The application

The efficient turning of organic materials to loosen, lift and aerate them is vitally important in industrial composting. This special agricultural mobile equipment ensures the fast drying of materials, optimal decomposition and reliable sanitisation, processing between 500 and 6,800 cubic metres of earth per hour.

An equipment manufacturer has introduced the feature of machine speed monitoring using an inductive sensor located in the rotor, which counts the passing teeth of a rotating mechanical disk. From the number of teeth per second, the controller then calculates the machine’s final drive speed.

Perfect sensor operation is required under these particularly harsh conditions. In addition to permanent vibration and shaking, the inductive sensor is also constantly exposed to dust, moisture, and temperatures from 70 to 80°C. Since the location of the sensor is in the rotor, it is hard to access and so the sensor must be very durable and maintenance free to avoid time-consuming repairs.

The solution

Contrinex inductive sensors from the Washdown sub-range of its ‘Extreme’ Robust family of stainless-steel sensors are perfect for this application. Made from a single piece of V4A stainless steel, which includes the sensing face, they have no covers, caps or welded seams that might break and are the most robust inductive sensors on the market. They resist shock, vibration, impact and abrasion and almost any exposure to dirt, gases, or liquids such as oil, water and cleaning agents. Functionally stable at temperatures from -25 to +85°C, they are also insensitive to core breakage.

Thanks to the long operating distances of these sensors (three times greater than the norm), a compact and efficient design was possible using an M12 sized inductive. The long operating distance allows the sensor to be mounted well away from the rotating disk’s passing teeth. Setup is also straightforward, as installation tolerances are less critical. A version with an M12 plug connector was chosen to allow speedy replacement if necessary, but even with the harsh operating conditions of this application, these sensors last several years and with minimal downtime, contributing to a reduction in repair costs.

Contrinex sensors and more information are available from PLUS Automation.