The present invention presents a way to manufacture in particular high quality cutting edges of a wiping lip that are usually used in wiper blades to wipe windscreens of a car. Herein two converging knives (110,120) are used together to cut the elastomer or rubber edge (180,190) from two different sides which are opposing each other and thus during the cutting operation provide a low irregularity which is below 1 µm. High quality is achieved by lowering the temperature of the elastomer or rubber during the cutting operation.
In order to avoid a knife penetrating and breaking through the elastomer or rubber edge the knives are coupled and movable with respect to the elastomer or rubber edge in a transversal direction thereof such that a similar distributed and balanced force is exerted by the two knives on the respective side of the elastomer or rubber edge. Oscillating movements that may occur during fast cutting speeds are dampened by damping means in form of hydraulic or elastomeric of friction means.
Also a method for measuring and determining the quality of the finished elastomer or rubber edge (180,190) during a manufacturing process is provided wherein the wiping lip is pressed against a surface (525) with a certain force (555) and at the same time hot or cold gas is blown against the edge and using thermographic imaging means to determine the gas distribution that penetrates between the edge and the surface as a measure of quality.