Velocity measurement on roll-fed material and piece goods

Velocity measurement is indispensable for process control and optimization in many industrial processes. It is the basis for many other applications such as cutting length control, length measurement, velocity difference. In these processes velocity is measured using the laser Doppler technique.

Laser surface velocimeters (LSVs) from Polytec are ideally suited because they can conduct measurements on almost any surface and they are not susceptible to contaminated surfaces. The non-contact measuring technique makes it possible to eliminate any negative influences on accuracy, such as slippage and wear, simultaneously. The product being subjected to the measurement remains intact too. Another benefit of Polytec systems is the flexible interface concept – it enables velocity readings via encoder output, serial interfaces, LAN, Profibus and Profinet.

Practical examples

Polytec LSVs are used for various velocity measurement tasks in the paper, cardboard and packaging industry:

  • dwell time determination in coating and surface treatment systems
  • cutting device control in cut-to-length processes
  • coil synchronization when winding sheet materials


Non-contact LSV velocity sensors in paper production

A Polytec LSV is installed in a paper factory because of frequent downtime when changing rolls of paper in its coating machine. Integrating the LSV into the process control allowed rolling velocities to be aligned exactly with one another with an accuracy of 0.1 %. This resulted in a significant reduction of tension fluctuations when joining the paper webs and has already led to savings equivalent to the investment costs in under a year.

Industrial length and speed control with optical sensors

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