For production reasons mineral wool is manufactured larger and thicker as it is subsequently sold. After production, the wool is trimmed and milled to the required thickness. optoNCDT laser sensors are used here as these provide reliable measurement values not only for solid and opaque media, but also for mineral wool. In order to measure wool thickness, the sensors operate in conjunction with a blower device and run on two tracks. The measurement values are then used to control the milling machine. An on-site CSP 2008 universal controller uses the values provided by the sensors to calculate and display the thickness.