Abstract: A device is disclosed for producing expanded material using cutting rollers of special design, in which the individual annular cutting rings on the cutting rollers are provided with notches in their lateral surfaces, and when the cutting roller is viewed from above, these notches are seen to be trapezoidal in shape. The invention relates furthermore to the special configuration of the stretching system, wherein the strip-shaped non-stretched material passing through is gripped laterally by two toothed belts while at the same time the material to be stretched runs up, in its center section, on a recirculating element, such as a rounde-section belt running at an appropriate speed. This belt rises far enough out of the plane of the toothed belts that the desired transverse stretching of the material is achieved.