The Optimization of Tool Life by Fillet Radiuson Cold Forging Die Using Finite Element and Low Cycle Fatigue Theory

Tool life prediction is an important thing in the metal forging industry. To prolong die life, proper die design is crucial. The objective of this work is to study the fillet radius effect to tool life on taperd cold forging process. The predicted tool life of cold forging die with high stresses used low cycle fatigue (LCF) theorem with strain-life approach (e-N). The cyclic properties of die material as used an estimation formula model. Commercial FEM software (MSC Marc) was used to simulate the cyclic stress in atapered cold forging die with an elastic-plastic workpiece and a deformable die. An implicit non-linear 2D axisymmetric model with 4 node quadrilateral elements was used. The friction between the die and workpiece, obtained from ball-on-disc testing was 0.115. The die and workpiece materials were AISI D2 and AISI 1045, respectively. The various fillet radius of insert die were 0.8 to 1.5 mm. The reference model with fillet radius 0.8 mm was used to tool life comparison between prediction and experiment. From analysis, it was found the maximum stress was 5,717MPa and the minimum stress was 528MPa, and the crack initiation on the insert die by predictionbeganafter299 forging shots. From the experimental results, a 1 mm radial crack was found on the fillet of the insert die at 450 shots. From comparison between prediction and experiment, the different value was acceptable. Further more, the tool life prediction result from varying fillet radius that found the fillet radius as 1.5 mm gave highest die life of 7, 356 shots. The difference of die life between die fillet radius as 0.8 and 1.5 mm was about 24.6 times. From this work, the fillet radius was found significant to die life by the FEM and LCF prediction. However, the predicted tool life just establish a simple guideline for experimental works. Furthermore, experimental work to compare with predictions is still necessary.