VLM sensor is needed for contact and slip-free yet highly accurate length measurement. It works in the finishing line of aluminium foil rolling mills without wear. The length of the coil is measured in the range of 10,000m to 30,000m. The foils are 0.03 to 0.3 mm thick. 0.025% safety margins are sufficient for the control of winders, so VLM is used.
