Analysis of punch velocity dependent process window in micro deep drawing

Micro forming is an appropriate technology to manufacture very small metal parts, in particular for bulk production, as they are required in many industrial products resulting from micro technology. Deep drawing provides a great application potential for the manufacturing of parts with complex shapes, even in very small dimensions. Concerning the so called size effects micro deep drawing is widely investigated. However, this process is carried out usually under laboratory conditions with a relatively low punch velocity, for example 1 mm/s. At the same time, the light weight of the forming tools for micro deep drawing makes it possible to vary the punch velocity in a relatively large range. Furthermore, raising the punch velocity is very meaningful for mass production in industry. Thus micro deep drawing with the punch diameter of 1 mm was performed with different punch velocities (1, 10 and 100 mm/s) in this work, whereby the process behaviour, especially the experimentally acquired process window changes with variation of punch velocities. The analysis in this work shows that the velocity dependent friction coefficients are responsible for the difference in process windows under different punch velocities.