Hans-Georg Rosen

Laser Machining Of Ceramic And Silicon

Ceramics and silicon are brittle materials, a fact that may cause problems and at the same time be helpful while machining with lasers. After giving a short introduction to ceramics different ways of cutting and drilling alumina (Al203) and silicon (Si) are discussed and compared to conventional methods. Examples from electronics industry with regard to types of laser, quality and velocity of process are presented.

Acoustic Emission And Its Application To Laser Spot Welding

A simple method for noncontact measuring acoustic emission generated during laser welding of steel X5CrNi18 9 and pure aluminium is presented. Laser beam quality is kept constant to insure that AE signal is just affected by the weld process. It will be shown that measuring in noncontact manner depends on formation of plasma, otherwise AE is generated due to backscattered laser radiation, which heat the fixture of the AE sensor.

Investigations for Detection of Splashes and Throughweld when Spotwelding with Pulsed Nd: YAG-Laser

Acoustic emission (AE) has been used by several authors to determine weld quality of laser beam welded samples. Of these, /1/ and /2/ use the same signal shape to detect different results. In each case the signal envelope consists of two distinct maxima. Stark claims that the second maximum reveals formation of splashes whereas Weeter finds this signal when sample is not welded through. It will be shown that second maximum is signal for splashes as well as incomplete weld through and that no second maximum occurs when welding through, even if splashes are present.