TY - GEN
T1 - Fracture mechanics based life prediction of hollow extrusion dies
AU - Qamar, Sayyad Zahid
PY - 2012
Y1 - 2012
N2 - Hot metal extrusion dies, especially for hollow profiles, are quite costly. Repair or replacement of dies and affiliated tooling adds to the cost, brings down productivity, and can contribute to product defects. Reasons for the high production and maintenance cost are stringent material requirements (highstrength and high-hardness tool steels), precision manufacturing methods (spark erosion, wire EDM, etc), and a series of specialized heat treatment and surface hardening operations. Consequently, a major goal for die designers and manufacturers is longer service life. An equally important objective is a reasonably accurate prediction of time-to-failure, to help devise an optimum replacement and inventory strategy, and for good performance evaluation. Majority of hot-work extrusion dies fail by fatigue fracture. Treating the die as a flat plate with edge crack, a fracture mechanics based fatigue life prediction model was developed by the authors in an earlier work. To improve the precision of die life prediction, a hollow (tube) extrusion die is modeled in the current work as a pressurized cylinder with internal crack. Based on this new strategy, a model is developed to forecast fracture failure of extrusion dies. Stochastic nature of various fatigue related die parameters is examined. Monte Carlo simulation is used for die life prediction under a given set of operating conditions and mechanical properties. Simulated fracture life values thus obtained are quite realistic in comparison with actual extrusion die life data from the industry.
AB - Hot metal extrusion dies, especially for hollow profiles, are quite costly. Repair or replacement of dies and affiliated tooling adds to the cost, brings down productivity, and can contribute to product defects. Reasons for the high production and maintenance cost are stringent material requirements (highstrength and high-hardness tool steels), precision manufacturing methods (spark erosion, wire EDM, etc), and a series of specialized heat treatment and surface hardening operations. Consequently, a major goal for die designers and manufacturers is longer service life. An equally important objective is a reasonably accurate prediction of time-to-failure, to help devise an optimum replacement and inventory strategy, and for good performance evaluation. Majority of hot-work extrusion dies fail by fatigue fracture. Treating the die as a flat plate with edge crack, a fracture mechanics based fatigue life prediction model was developed by the authors in an earlier work. To improve the precision of die life prediction, a hollow (tube) extrusion die is modeled in the current work as a pressurized cylinder with internal crack. Based on this new strategy, a model is developed to forecast fracture failure of extrusion dies. Stochastic nature of various fatigue related die parameters is examined. Monte Carlo simulation is used for die life prediction under a given set of operating conditions and mechanical properties. Simulated fracture life values thus obtained are quite realistic in comparison with actual extrusion die life data from the industry.
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U2 - 10.1115/IMECE2012-93109
DO - 10.1115/IMECE2012-93109
M3 - Conference contribution
AN - SCOPUS:84887283540
SN - 9780791845196
T3 - ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)
SP - 1719
EP - 1725
BT - ASME 2012 International Mechanical Engineering Congress and Exposition, IMECE 2012
T2 - ASME 2012 International Mechanical Engineering Congress and Exposition, IMECE 2012
Y2 - 9 November 2012 through 15 November 2012
ER -