Product Code: ICAL09_M802

Laser Micro Sintering - Upgrade Technology
Authors:
André Streek, University of applied science Mittweida; Mittweida Germany
Peter Regenfuss, University of Applied Science Mittweida; Mittweida Germany
Robby Ebert, University of Applied Science Mittweida; Mittweida Germany
Horst Exner, University of Applied Science Mittweida; Mittweida Germany
Presented at ICALEO 2009

Laser micro sintering is a technology that has proved suitable for the generative production of bodies with structural resolutions down to 25µm. It is a modification of selective laser sintering, a freeform technology for the generation of three-dimensional parts by repeatedly coating thin powder layers onto a substrate and sintering the cross-section of the intended geometry with a laser beam. Before the first results were achieved with laser micro sintering in 2003 the conventional methods of selective laser sintering had been unable to produce differentiable structural features below 100µm. From the very beginning of laser micro sintering the low grain size of the powders (in the range of 1µm and below), that is considered one of the prerequisites on the one hand, has also been one of the complicacies on the other hand. Yielding very low packing densities when coated with a doctor blade (which in the case of laser micro sintering has the shape of a hollow cylinder), laser sintering of these powders required a new laser regime with condensing properties. This was achieved with a regime of q-switched laser pulses during which a plasma plume, and possibly subsequent boiling effects, exert a transient shock wave or pressure jump onto the processed material. One of the detrimental effects of the q-switched regime is that the bodies, especially the ones sintered from one-component metal powders, showed a noticeable porosity. Meanwhile a new technique of mechanically compressing each powder layer previous to laser micro sintering makes it possible to achieve relative sinter densities of 97% with metal powders.