Patent ID: 7721405

Claim:
A method for joining at least two plate-shaped workpieces of similar or different materials by means of a fastening tool including a punch for exerting punch forces to perform a joining operation at a joining area and including a clamp for exerting clamping forces upon said workpieces supported against a die, the method comprising the steps of: during the joining operation, exerting a first punch force to perform the joining operation; throughout the joining operation, limiting a first clamping force from the clamp at the joining area, wherein the first clamping force permits free material deformation at the joining area; after the joining operation, exerting a second clamping force; and after the joining operation, exerting a second punch force, wherein the second punch force and the second clamping force are exerted at the same time to reduce deformations of the workpieces and to provide for compression of the workpieces at the joining area.