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EMG strip guiding systems: Know-how for the user - 10

One-sided inductive strip edge position measurement for rolling mills (VKI3)

Schematic representation of the VKI3 - one-sided strip position measurement in the rolling mill on minimum space with wear plate (white)

In this and the following articles in this series, we summarise know-how on the use of EMG strip guiding systems and try to provide you with the necessary basics for planning the components that can be used and for designing the systems.

Published so far: 


Application and use

In cold rolling mills in particular, reliable detection of the strip position is a basic prerequisite for achieving the desired rolling result and for safe plant operation.

The EMG VKI3 measuring device uses an inductive measuring principle with a coil system which reliably detects the exact strip edge positions of metal strips and metal foils contact-free in the ambient conditions of a rolling mill with strong rolling oil deposits, mist and dirt. It detects the absolute strip edge position of all metallic materials on one side by means of the eddy currents generated in it. 

A sturdy aluminium housing protects the measuring electronics against water jets and temporary immersion in liquid. The compact measuring beam contains one electric motor-driven adjustment slide per strip edge side, which move the inductive edge sensors transversely to the strip running direction. The sensors transmit the momentary coverage by the strip edges to the integrated electronic unit and thus follow the assigned strip edge. From the position values and the sensor coverage, the positions of both strip edges, the position of the strip as a whole and optionally the strip width are calculated. Due to the material-dependent measuring technology, the strip centre measurement achieves the best measuring accuracy. The VKI3 is to be protected by an additional wear plate and thus achieves protection class IP65 and IP67.

The VKI3 can be used as a stand-alone unit for optimising flatness measuring rolls or in combination with an EMG control amplifier and actuator for strip positioning.

Ideally, the system should be placed as close as possible to a deflection roll (e.g., flatness measuring roll).



VKI 3 is available in different designs:

  • K: Edge measurement
  • M: centre measurement
  • G: Centre measurement for narrow strips


Selected features

  • One-sided strip edge or strip centre measurement
  • Positioning speed of the sensors: 30 mm/s 
  • Temperature range: 0 to +50 °C; up to +80 °C (with water cooling of the sensor system) 
  • Measuring accuracy strip centre position: +/- 1 mm (with flat strip shape, +/- 10 mm height change, constant material thickness, same material type and pass line at 20 mm) 
  • Measuring distance to the strip running plane: up to 40 mm from sensor without slide plate 
  • Minimum strip width: 300 mm for detection of one strip edge or 400 mm for detection of both strip edges (smaller strip widths on request)
  • Digital bus communication: Profibus, Ethernet Modbus TCP, Ethernet Socket TCP


Which components are used?


How and where can I get support?

Know-how and support in the design, construction and installation of strip guiding solutions for your production line are concentrated at EMG! Our sales and service staff, our international sales organisation or our product management ( can provide you with concrete advice on the design of your control and sensor equipment at any time. 

Just get in touch with us!



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