Experimental study of failure modes and scaling effects in micro-incremental forming

Incremental forming (IF) is a relatively new technique that uses a simple hemispherical ended tool moving along a predefined three-dimensional toolpath to deform a sheet of metal into the desired shape. The greater process flexibility and higher formability in IF have resulted in greater academic and industrial interest in this process as it can successfully produce ultrathin parts beyond the forming limit seen in conventional stamping and the process does not require any geometry-specific tooling. Another emerging paradigm in manufacturing has been the increasing application of forming in micromanufacturing. The above stated process characteristics of IF make it an ideal candidate for being incorporated into the micromanufacturing paradigm. This work investigates micro-IF to examine how forces and occurrence of sheet failure change when the geometric dimensions of incremental forming are scaled down. The development of a highly repeatable micro-IF experimental setup is described and experiments are performed to show that a previously unknown buckling mode of deformation exists in micro-incremental forming, that is linked to the material microstructure. The analysis provides guidelines for the design and understanding of the micro-incremental forming process.