The quality and precision of forming processes depend decisively on the mechanical performance and condition of the machine used. Especially in demanding forging, cutting and forming processes, the reaction of the machine used to different load situations is of central importance.

In order to systematically record these aspects, the term "machine fingerprint" has become established among our customers  . The machine fingerprint refers to the unique, quantified signature of a machine that is derived from its reaction to a series of standardized load cases. On this page, we explain how we create the standardized machine fingerprint for forming machines, which measurands and operating conditions play a role in this, and what insights can be gained from it for process optimization, quality control and the machine design cycle.

The machine fingerprint is a measurement data profile that describes the mechanical properties of a machine depending on standardized load situations. The basic idea is analogous to biological fingerprints: Every machine has characteristic properties that can be systematically worked out and recorded. The fingerprint is a set of key figures and diagrams that depict not only the instantaneous performance, but also the stability and behavior under varying loads.

In order to create a comparable and reproducible fingerprint, a standardised procedure is required. Since the machine fingerprint is intended to reflect the behaviour of systems under operating loads, all measurements are carried out in automatic system operation under gradually varying load situations. For statistical validation, the dispersion of the recorded forces and stroke rates is recorded during the measurement. Only if the dispersions are within an acceptable range is the measuring point adopted as valid, otherwise the measurement setting must be checked and repeated:

On the one hand, fingerprint data describes the technical capacity of plants under nominal encumbrances. In practical terms, the following conclusions can regularly be derived:

One system shows conspicuous tilting tendencies around the x- and y-axis.

• In this case, after consulting the machine manufacturer, an inspection of the guide system may be indicated.
• Tilting under the stroke can lead to service life and quality problems, especially in cutting operations with narrow cutting gaps. A tilt measurement during the process can help to ensure this. The fingerprint can be used to determine the permissible off-center force for adjusting tilts. This gives the toolmaker extended information on the gradation of tools and adjustment of spring packages.

One system shows low attenuation after impact / release from the reference load cells.

• Such machine properties can be critical, especially in the case of impulse-like process events, because oscillation cycles are introduced into the structure without damping and can thus ignite aging effects at an early stage through interplay.
• In the case of slow-running processes, large impact events can occur, e.g. cutting impacts, touchdowns and the acceleration of large hold-downs in the return stroke.

Evaluation of the system stiffness and force build-up:

• Mechanical presses, while neglecting the flywheel mass effects of the ram mass, can only generate the required force effect through their elastic behavior.
• Typical compliance (1/c) of mechanical presses is roughly in the range of 0.1 mm / 1 kN.
• In the overall context, the fingerprint methodology also allows to estimate the force build-up in the process, because the ram mass and impact velocity (calculated from position data)

By comparing such parameters, the suitable machine for a particular forming process can be selected and potential areas for optimization can be identified at the same time.