DETERMINATION OF FORMABILITY CHARACTERISTICS OF SHEET METALS THROUGH ERICHSAN CUPPING TEST

Erichsan cupping test is one of the formality testing of sheet metals in sheet metal forming analogy. It is used for evaluation of formability characteristics of sheet metals. This test is the inward drawing of sheet blank with stretching methodology. In this test a spherical punch is used to evaluate the formability characteristics of sheet metals. This test deforms the blank into the shape of hemispherical dome. The formability characteristics such as Erichsan number and peak load can be determined through the Erichsan cupping test. In general drawing process the sheet is formed to cup shape. The tensile forces produced sheet metal and it is stretched radially, but it circumferentially compressed due to punch force. In Erichsan cupping test, a single specimen with required dimension drawn into cup until the fracture occurred at dome of cup by the force applied through continuous movement of hemispherical punch into specimen of sheet metal. In this test the cup height at fracture and peak load is measured. These are used as a measure of the formability index. Cup height at fracture in ‘mm’ is measured as Erichsan number. Cup height at fracture is used as the measure of stretchability. The formability can be expressed as erichsan number and peak load. In this test the formability characteristics of sheet metals such as alloys of aluminum, mild steel are studied through finite element analysis.