The Experimental Investigation of Punching of the AM60 and AZ61 Magnesium Alloy Sheets by Using Varied Punch Shapes

The using of magnesium alloys for industrial sheet metal part production has become increasingly common in recent years. This research aims to characterize the effects of the cutting-edge shapes of the punches on the blanking forces and the sheared edge qualities in the blanking/piercing operations of magnesium alloy sheets. Magnesium sheets (AM60 and AZ61) were produced by casting and rolling processes. AM60 and AZ61 Mg alloys produced by casting were rolled by using two different speeds, 2.5 m/min and 7.5 m/min. Material thickness was adjusted to three mm in the rolling process. Blanking tests were carried out on a die-set and hydraulic press by varying shaped punches. In the experimental studies, flat-ended, concave shaped, and 16° angled punches were used. A loadcell was fixed to the experimental setup to determine the blanking forces. The results showed that the AM60 alloy was more resistant to shearing than the AZ61. The lowest blanking force was obtained by use of the 16° angled punch. It was determined that the using of flat-ended punches for blanking operations was more convenient according to the usage purpose of the parts while all three punches can be used for piercing operations.

Punching test for estimating tensile strength and total elongation of steel sheets

A punching test for simply estimating the tensile strength and total elongation of steel sheets and formed parts was proposed. The tensile strength and total elongation were estimated from the shear stress at the maximum punching load and percentage of the burnished depth at the sheared edge of the slug measured without cutting, respectively. For a variety of steel sheets with a range of the tensile strength from 360 to 1500 MPa, linear functions for the estimation were experimentally obtained. The correlation of the estimated tensile strength of the steel sheets with the measured one from the uniaxial tensile test was considerably high, and the correlation of the estimated total elongation was high. The distributions of tensile strength and total elongation for hot- and cold-stamped parts were estimated. The proposed punching test is available under not only a laboratory environment but also a factory environment.