Overband Magnet Extended by 56%

A challenging installation on mobile recycling plant led to Bunting designing and building a Permanent Overband Magnet with a magnet block over 56% longer than normal.  The model PIL Overband Magnet was extended from the standard length of 1100mm to 1725mm.

Permanent Overband Magnets are suspended over conveyor belts transporting material to separate ferrous metals, before automatically discharging the metal into a separate collection area.  A typical Overband Magnet has two pulleys mounted either side of a strong permanent magnet block, over which runs a cleated rubber belt driven by a hydraulic motor.

Extended Overband Magnet

In this installation on a mobile crusher in Austria, the Overband Magnet was mounted in-line with the conveyor, over a non-magnetic head pulley.  The cleaning belt of the Overband Magnet is moving in the same direction as the conveyor, but at a higher speed.  Ferrous metal lifts up and out of the conveyed material towards the magnet face, before being transferred by the cleated rubber belt into a separate metal collection chute.

• Technical product details: Overband Magnets

However, the ferrous metal transfer distance, between the head pulley and the discharge point, was too long for a standard length Permanent Overband Magnet.

The task for Bunting’s design engineers was to design a bespoke Overband Magnet.  The extended length of the magnet block in the new model 12 PIL 8 Tri-Polar Overband Magnet is 1725mm, compared with the standard 1100mm, raising the overall length from 2970mm to 3300mm.  The increased magnet length increased the total weight by 59%.

“Some applications require bespoke design,” explained Adrian Coleman, Bunting’s European Group Technical Director.  “When extending the magnet box we were focused on maintaining the deep and strong magnetic force required for optimum separation.  The final design met all the dimension and performance criteria for the installation.”