A numerical study on the warm deep drawability of polypropylene under differential heating conditions

Abstract Warm deep drawing of polypropylene blanks to form flat‐bottom cylindrical cups under differential heating conditions is numerically investigated using finite element analysis. Differential heating involves heating only the flange area of the blank to an elevated temperature while the punch area of the blank remains at 25°C. The effects of initial flange temperature, blank diameter, blank holder force, punch corner radius and die corner radius on the depth of draw are studied. Comparisons are made between depths of draw obtained in differential heating and homogeneous heating in which the entire blank that includes its flange as well as punch areas is heated to the same temperature. It is shown that significantly higher draw depths can be obtained with differential heating for the cups with sharp punch corner radius of 3 mm and lower. Variations in thickness, temperature and plastic strain in the deep drawn cups, punch forces, and failure modes are also determined. Highlights Differential blank heating gives higher draw depths with sharp punch radius. Draw depth increases with increasing die corner radius. Draw depth increases with increasing temperature differential. Draw depth increases with decreasing blank diameter and blank holder force. In differential heating, blanks fail at die corner instead of punch corner.