How to Determine the Drop in Steel Shapes

Consider how common the steel shape is. In closed-die forging, hot steel is hammered between two die that act almost like a pair of molds. As the top die comes down, it forces the steel to fill the empty space in the mold to create a standard shape. If your steel shape is a common object, like a particular brand of knife, the drop forging method was likely closed die. If your shape is more unusual, like a customized steel girder for a construction project, the drop was likely open die. In this second method, the top die acts more like a blacksmith̵7;s hammer to bash the steel into shape.

Check how heavy the object is. Closed-die forging can produce parts of up to 25 tons, but steel parts forged using open die can weigh as much as 150 tons. If your steel shape is particularly heavy the drop was likely open die.

Inspect how neat the object is. Because closed-die forging forces the steel into a mold, it will have a uniform shape every time. In open-die forging the operator must manually turn the steel to hammer it into the desired shape. While this allows greater customization, it produces a less-finished product with a higher margin of error. Neat edging on an object therefore suggests that the drop was closed die.