Innovative System for Automated Measurement of the Distribution of the Length of Natural Fibres

The quality and stability of materials or products containing natural fibres (textiles, fleece, fibre-reinforced materials) is mainly determined by the length of the employed natural fibres. In this paper we present a novel method and device for optically determining the length distribution of natural fibres. A fibre bundle consisting of fibres with varying lengths is put on a combed bed where a gripper pulls the fibres at their one end. A laser line is projected onto the fibres and the reflected light is detected by a line sensor taking grey-scale pictures with a frequency of 8 kHz. This image stack can be analysed and the lengths of the fibres may be determined. To date, the maximum length of fibres to be measured is 130 mm. The resolution of the device has been proved to be 20 microns for a bundle width of 130 mm. In addition to that, the distribution of the width of single fibres can be determined, as well. The measuring method may be easily extended to other measurement parameters, such as fibre colour.