Sheet-metal forming is a basic metalworking and metal-processing technique and is among the oldest production technologies. 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-tensile and ultra-high-tensile steel materials, although their reduced ductility and higher elastic recovery are setting new challenges for forming technology and process control.
Sheet metal testing machines assist in the process of development in characterizing new alloys and new metalworking technologies, as well as in eventual series production. Zwick sheet metal testing machines score with their flexibility, fast, easy fixture changes for different tests and individually controllable integrated functions such as holding down, punching, drawing and ejection.
Typical sheet-metal forming applications include the classical Erichsen cupping test (EN ISO 20482), the earing test (EN 1669) and hole-expansion tests, which are seeing increasing use with high-tensile steel materials.
Particular importance is attached to determination of the forming limit curve (FLC), which is used in a two-stage experiment to generate critical deformations in tests. These are then compared with existing deformations on actual components and evaluated. Once the FLC has been determined, it is used at the component design stage to help optimize forming, thereby speeding up the development process. In addition to a sheet metal testing machine, these tests (ISO 12004) require a suitable optical evaluation system.
Spring-back properties are generally determined on customer-specific specimens. Similarly, customized fixtures incorporated into the sheet metal testing machine allow tests to be performed quickly and easily.