1. Case study: sockets (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: cold forging of non-cylindrical sockets (2D analysis) Die geometry: Forging of a non-cylindrical socket, fillet radius R4 Die material: Carbide or PM steel Prestressing system: ID 40 mm, OD 120 mm 2D model of the die prestressed by STRECON E + Stripwinding and casing E=205 GPa, =0.3, elastic Carbide winding core E=540GPa, =0.23, elastic Die: Carbide: E=340 GPa, =0.23 PM steel: E=225GPa, =0.3 elastic-plastic load: 1600 MPa

2. Case study: sockets (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 Design A: Prestressing by a double stress ring at 0.6% interference, carbide as die material Tangential stress distribution at max. process load Tangential stress-strain response in the fillet (for two load cycles)  high tensile stresses at max. load, high stress range, high cyclic plastic strains 1500 1200 900 600 300 0 -300 -600 -900 -1200 -1500  = 3760 MPa  pl = 0.36 % 1360 MPa MPa

3. Case study: sockets (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 Design B: Prestressing by a STRECON ® E + container at 0.5% interference, carbide as die material Tangential stress distribution at max. process load Tangential stress-strain response in the fillet (for two load cycles)  reduced tensile stresses at max. load, reduced stress range, reduced cyclic plastic strains -125 MPa  = 3180 MPa  pl = 0.16 % 375 MPa 1500 1200 900 600 300 0 -300 -600 -900 -1200 -1500 MPa

4. Case study: sockets (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 Design C: Prestressing by a STRECON ® E + container at 0.6% interference, PM steel as die material Tangential stress distribution at max. process load Tangential stress-strain response in the fillet (for two load cycles)  no tensile stresses at max. load, further reduced stress range, minimized cyclic plastic strains in combination with a die material with considerably higher fatigue strength -125 MPa  = 2700 MPa  pl = 0.04 % -20 MPa 1500 1200 900 600 300 0 -300 -600 -900 -1200 -1500 MPa

5. Case study: sockets (5) 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: cold forging of non-cylindrical sockets (3D analysis) Die material: Cold-working steel 56 HRc Prestressing system: ID 60 mm, OD 130 mm 3D model of the die, here prestressed by STRECON E + Stripwinding and casing E=205 GPa, =0.3, elastic Carbide winding core E=540GPa, =0.23, elastic Die, E=225GPa, =0.3 elastic-plastic

6. Case study: sockets (6) 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 Typical failure mode

7. Case study: sockets (7) 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 Prestressing by a double stress ring at 0.6% interference Circumferential stress distribution at max. process load  risk of early crack initiation due to tensile stresses at maximum process load, large stress range and high cyclic plastic strains  = 2500 MPa 800 640 480 320 160 0 -160 -320 -480 -640 -800 MPa Tangential stress-strain response in the fillet (for one load cycle) 820 MPa

8. Case study: sockets (8) 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 800 640 480 320 160 0 -160 -320 -480 -640 -800 Prestressing by a STRECON AXI-FIT E + at 0.6% interference Circumferential stress distribution at max. process load MPa Tangential stress-strain response in the fillet (for one load cycle) 220 MPa  = 2150 MPa  Improved fatigue strength due to the reduction of tensile stresses and the reduction of the stress range

9. Case study: sockets (9) 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 Recommended prestressing system for sockets: STRECON AXI-FIT (E + ) winding core made of steel (Basic) in case of cylindrical sockets tungsten carbide (E + ) in case of non-cyclindrical sockets axial prestressing

10. Case study: sockets (10) 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 Recommendations for the design of dies for the cold forging of sockets Recommended die material: Powder-metallurgical steel provides an excellent fatigue strength Recommended prestressing system: STRECON ® AXI-FIT: the additional axial prestressing (AXI-FIT) reduces the risk of horizontal cracks STRECON ® AXI-FIT E + in case of non-cylindrical sockets: the higher sitffness reduces the stresses and cyclic plastic strains in the corners