Peter Regenfuss

Selective Laser Micro Sintering with a Novel Process

Microparts with a structural resolution of <30μm and aspect ratios of >12 have been generated by selective laser sintering. The technique includes sintering under conditions of vacuum or reduced shield gas pressures. In a novel set-up the material is processed by a Q-switched 1064nm Nd-YAG laser after a special raking procedure. The procedure allows the work pieces to be generated from powders of high melting metals like tungsten as well as lower melting metals like aluminium and copper. Contingent on the parameters, the generated bodies are either firmly attached to the substrate or can be dissevered by a non-destructive method.

Process assembly for μm-scale SLS, reaction sintering, and CVD

A novel device suited for the generation of sintered microparts of metal and ceramics, for reaction sintering and for CVD has been developed and successfully tested. With the production of a functional component it has evidenced professional performance. The set-up is vacuum tight; unstable substances can be processed under various shield gases and pressures; it is equipped with a device suited to rake thin layers of fine powders as well as slurries. Sub micrometer powder can be processed in steps of 1 μm thick sintered layers. In combination with a proprietary sintering regime, micro parts with a structural resolution of <30μm, and aspect ratios of >10 have been achieved.

Laser microsintering of tungsten in vacuum

Laser microsintering of tungsten powder is investigated as a function of laser output power, pulse interval and vacuum level. The intensities are calculated for the evaporation thresholds of tungsten powder particles of various sizes. In addition, the powder layer generation and the resulting layer thicknesses are calculated. The powder abrasion occurring during the process was taken into consideration. Polished sections and REM images were prepared in order to analyse the experimental outcomes. The dependence of sinter density on the parameters is discussed.

Laser micro sintering - Upgrade of the technology

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 effect...