Hand in hand with other mechanical tests the Erichsen cupping test, also called deep-drawing test, is used to determine the propensity of a material to undergo certain deformation processes.
In particular, the deep-drawing test (ISO 20482) intends to verify the material’s aptitude to assume hollow or shaped shapes and its suitability for medium depth molding.
In the Erichsen cupping test a sheet metal sample, locked in a die, is drawn by a spherical cap punch or by a sphere up to the breaking point. The elements are arranged so as to have a clamping force of 10kN and the punch is advanced slowly so that the deformation of the sample occurs only in the affected area and not thanks to the addition of material from the sides. At the end of the test, the depth of the drawing is measured in millimeters. Therefore, the value obtained indicates the elongation capacity for a sheet of a certain thickness (usually between 0.1 and 2 mm).
The average value of the deep drawing of at least three tests is the Erichsen index (IE).
It is possible to establish indicative values of the Erichsen index for sheets from cold rolled strips as per table:
AISI | Thickness (mm) | Erichsen index (mm) |
Aisi 430 – 1.4016 | 0.4 | 8.07 |
Aisi 430 – 1.4016 | 0.5 | 8.38 |
Aisi 430 – 1.4016 | 0.6 | 8.75 |
Aisi 430 – 1.4016 | 0.8 | 9.05 |
Aisi 304 – 1.4301 | 0.5 | 11.5 |
Aisi 304 – 1.4301 | 1.0 | 12 |
Aisi 304 – 1.4301 | 1.5 | 13 |
Aisi 304 – 1.4301 | 2.0 | 14 |
Aisi 304 – 1.4301 deep drawing | 0.5 | 12 |
Aisi 304 – 1.4301 deep drawing | 1.0 | 13 |
Aisi 304 – 1.4301 deep drawing | 1.5 | 14 |
Aisi 304 – 1.4301 deep drawing | 2.0 | 14.8 |
Aisi 316 – 1.4401 | 0.7 | 12.3 |
In general, austenitic stainless steels that have the highest percentages of Nickel also have the greatest elongation and formability characteristics.
INOXVENETA tests each production batch intended for drawing operations. The Erichsen test is able to predict with excellent approximation the suitability of the tested sheet for the realization of medium drawing.