Tool geometry effects in metal shearing using FEM
Barkan, Eric David.
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In manufacturing industry cutting of sheet metals is an everyday occurrence. With this in mind hand tool design is limited by empirical conventions for tool clearance, in the range of 4.5% to 8%. Conventional cutting force calculations and tool clearance calculations exist in reference material and can easily be calculated. These conventions are based on shear theory for force and experimental data for tool clearance. By applying these conventions to an FEM model for common engineering alloys of thicknesses between .020" and .080", and analyzing it the resulting stress fields and tool displacements trends in the increase of tool displacement required for the same stress state for all tool clearances. Cohesive zone placement based on first analysis leads to describing the failure of the material cutting process. Traction separation laws describing cohesive elements can accurately describe the cutting of sheet metals. For the 6061-T6 aluminum, 1020 steel, 4340 steel, and 302 stainless the optimum tool clearance discovered through the cohesive zone FEM model is shown to be 3.8% to 8.3%. This information can be used for extrapolating the optimum clearances for other thicknesses of the materials, and the model can be expanded to encompass a larger material set.