Laser micro sintering - Upgrade of the technology

Abstract

Laser micro sintering, a modification of selective laser sintering for the freeform fabrication of micro-parts, has been developed continuously since its first application. The main feature of the original regime was the application of non-overlapping q-switched pulses which was required because of the poor density of the powder layers and the concomitant need for a compacting effect during the laser sinter process. Next to some unanticipated positive side effects of this regime, poor compactness of the products had to be taken into account frequently as a detrimental consequence. Recently an upgraded coating routine has been developed that contains a compaction-step of the powder coating prior to the sintering of each layer. After appropriate adaption of the laser regime micro-parts with considerably higher densities can be achieved now. Process observations and the properties of the sintered solids give evidence that a different sinter mechanism takes place with its own negative and positive side effects. The conclusion can be made that, with sufficiently compacted powder layers and sufficient control of the coating, even laser micro sintering with continuous radiation might be feasible. Direct generation of highly miniaturized machines with encased freely movable entities by the upgraded technique has been proved. The new technology is named HD-LMS (“High Density-Laser Micro Sintering”).