Experiments and finite element analysis of galling behavior in square cup drawing

During the sheet metal forming (SMF), one of the major causes for die failure is transfer and accumulation of adhered material to the die surface, generally referred to as galling phenomenon. In the present work, the galling behaviour in macro-scale of several die materials was investigated against the high tensile strength steel under semi-dry and dry condition on laboratory experiments. The galling evaluation was carried out with different materials by using a separated cup square drawing die. Meanwhile, the finite element method with DEFORM-3D was used to simulate the square cup drawing process based on the drawing force distribution and volume change analysis, which gave us a rational interpretation of the galling phenomena and illustrated the galling behavior and seizing tumour theoretically. As a result, the galling on the die surface occurs at the bottom point of the boundary between the straight and corner edge, and grows upward with the drawing cycles. On the drawn cup, the galling starts at the top of the same boundary and grows downward. Moreover, any adhesion can not be found on the coated die for DLC-Si (DC-PACVD) even after 1000 drawing cycles, which showed a better anti-galling behavior against the high tensile strength steel.