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. For determining the length of cut rings and recording it with ring length controller, VLM device is used for accurate measurement in order processing and quality assurance. Cold rolled metal strips are made up in rings at the finishing lines.
