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 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.