1. Case study: variable adjustment of inner diameter (1) Established within the GROWTH project GRD1-1999-10748 "Improvement of Service Life and Reliability of Cold Forging Tools with respect to Fatigue Damage due to Cyclic Plasticity (COLT)", funded by the European Community. COLT Design Manual for Cold Forging Dies Case study: net-shape forging in close tolerances by STRECON ® VARI-FIT Example for net-shape forged spline on hollow steering shaft Model of a STRECON ® VARI-FIT

2. Case study: variable adjustment of inner diameter (2) Established within the GROWTH project GRD1-1999-10748 "Improvement of Service Life and Reliability of Cold Forging Tools with respect to Fatigue Damage due to Cyclic Plasticity (COLT)", funded by the European Community. COLT Design Manual for Cold Forging Dies Principle design of a STRECON ® VARI-FIT die insert carbide winding core stripwinding intermediate rings axial prestressing Strip-wound container with carbide winding core Combined radial and axial prestressing Change of the inner diameter of the die by controlled axial displacement of the die Intermediate rings define the axial position of the die Quick disassembly and assembly for rearrangement of the intermediate rings lowest position  maximum diameter highest position  minimum diameter

3. Case study: variable adjustment of inner diameter (3) Established within the GROWTH project GRD1-1999-10748 "Improvement of Service Life and Reliability of Cold Forging Tools with respect to Fatigue Damage due to Cyclic Plasticity (COLT)", funded by the European Community. COLT Design Manual for Cold Forging Dies Example: Inner diameter of the die insert: Ø28mm Die insert material: WC or HSS prestressed by STRECON ® VARI-FIT die made of high-speed steel: circa 3 µm diameter change per 0.1 mm axial displacement die made of carbide: circa 2 µm diameter change per 0.1 mm axial displacement Variable adjustment of the inner diameter of the die

4. Case study: variable adjustment of inner diameter (4) Established within the GROWTH project GRD1-1999-10748 "Improvement of Service Life and Reliability of Cold Forging Tools with respect to Fatigue Damage due to Cyclic Plasticity (COLT)", funded by the European Community. COLT Design Manual for Cold Forging Dies Turning Heat Treatment Grinding EDM Polishing Coating Serial production and on-going inspection no in case of conventional prestressing systems no in case of STRECON ® VARI-FIT Shortening the process chain of manufacturing and set-up of dies by STRECON ® VARI-FIT OK? Prestress-Assembly Tool set-up in the press Forging and inspection of samples OK?