Loss of wire tension in the wire web: Towards stable cutting conditions for all wafers

Changes of wire quality from one end of a wire web in a multi wire saw to the other are investigated by several methods: wire tension measurements in the wire saw, wire elongation during an industrial process and tensile tests of representative wires. Two mechanisms for the loss of wire tension are identified. First, the decrease of wire diameter causes a slow loss of wire tension along the whole wire web. Second, plastic deformation leads to a fast decrease of the wire tension within the first few centimeters of the wire web. Both effects are confirmed by modeling and calculations.