Forming Behavior during Joining by Laser Induced Shock Waves

Abstract

The ongoing trend of miniaturization makes hybrid joint also for the micro range necessary. Existing solutions often have restrictions due to the principle of joining. Therefore a new joining technology, which is realized by a plastic forming process based on TEA-CO2-laser induced shock waves, is used at BIAS. This technology enables the joining of different sheet materials with thicknesses between 20 µm and 300 µm. The manufacturing of the joint is an incremental process where several laser induced shock waves are needed to form the undercut, which presents the joint itself. For the analysis of the incremental forming behavior of this process a 50 µm thick forming sheet of aluminum (Al99.5) is joined with a 100 µm thick stainless steel (1.4301) die sheet. The first ten laser pulses are leading to relative high induced strain while for forming of the undercut 200 laser pulses are needed. The incremental induced strain per laser pulse decreases exponentially with the amount of used laser pulses. This behavior is explained by the acting pressure distribution of the induced shock wave and the contact area.