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Test Methods for Sheet Metal Forming

Test methods for sheet metal forming provide characteristic values for metalworking and metal processing and include tests such as cupping tests, earing tests and hole expansion tests. 

In forming technology thin sheets are treated in various manufacturing processes such as rolling, open die forging, impact extrusion, extrusion molding, deep drawing or bending. Sheet metal forming in particular is one of the oldest production technologies. It is used to turn a flat sheet metal blank into its final shape.

Innovation is largely driven by transport technology, particularly the automotive industry. Increasing demands on sheet metal materials under the general heading of lightweight construction have led to the development of high-strength and ultra high-strength steel materials, although their reduced ductility and higher elastic recovery are setting new challenges for forming technology and process control.

Typical Test Methods for Sheet Metal Forming

Typical sheet metal forming test methods include the classical cupping test to Erichsen (ISO 20482) and Olsen (ISO 20482), the earing test (ISO 11531 / EN 1669) and hole-expansion tests to ISO 16630, which are seeing increasing use with high strength steel materials.

Particular importance is given to determination of the forming limit curve (FLC) to ISO 12004, which is used in a two-stage experiment to generate critical deformations in tests, which are then compared with existing deformations on real components and evaluated. Once the forming limit curve (FLC) has been determined, it is used during the component design stage to help optimize sheet metal forming, thereby speeding up the development process.

Cupping test to Erichsen/Olsen

Cupping tests to Erichsen (ISO 20482) and Olsen (ASTM E643) are used to determine the stretching capacity a of sheet metal.
to Cupping test to Erichsen/Olsen

Earing test on metal/aluminum

The earing test on metallic materials (ISO 11531) and aluminum (EN 1669) is used for determining ear formation.
to Earing test on metal/aluminum

Hole Expansion Test

The hole expansion test is used for the determination of edge crack sensitivity
to Hole Expansion Test

Forming limit curve (FLC)

With a forming limit curve to ISO 12004, the failure limit of a sheet metal can be determined.
to Forming limit curve (FLC)

Additional Test Methods for Sheet Metal Forming: Cupping tests

Hydraulic bulge test

In a bulge test to ISO 16808 biaxial stress-strain curves are determined using a hydraulic cupping test.
to Hydraulic bulge test

VW test

In the VW test, the waviness of sheet metal for the body exterior is tested.
to VW test

Additional Test Methods for Sheet Metal Forming: Earing tests

Earing test to Fukui

For the Fukui conical cup test, conical cups are stretched and pulled
to Earing test to Fukui

Square cup test

For the square cup test, cups are drawn with square bases.
to Square cup test

Limiting Drawing Ratio Test (LDR)

For the limiting drawing ratio (LDR) test, or Swift deep drawing cup test, the maximum ratio of circular blank to die diameter is evaluated.
to Limiting Drawing Ratio Test (LDR)

Limiting dome height (LDH) test

For a limiting dome height (LDH) test a hemispherical die is used to strain the clamped specimen until break.
to Limiting dome height (LDH) test

Deep drawing tear-off test to Engelhardt

For the deep drawing and tear-off test to Engelhardt the necessary drawing force and force required to cause bottom cracks during the earing test are measured.
to Deep drawing tear-off test to Engelhardt

Additional Test Methods for Sheet Metal Forming: Hole expansion tests

Hole expansion test to KWI

For a hole expansion test to KWI a hole is stretched with a flat deep drawing die and the change-in-shape property of the sheet metal is determined.
to Hole expansion test to KWI

Additional Test Methods for Sheet Metal Forming:

U-bend test

The u-bend test is used to test finishes and coatings on sheet metals.
to U-bend test

Related Products for Determining Characteristic Values in Sheet Metal Forming