Combination of Yb:YAG-disc laser and roll-based powder deposition for the micro-laser sintering

Abstract

Miniaturisation is one of the key technologies of the 21st century with a wide range of demands for the manufacturing of plastic components with resolution in the micron scale (e.g. microstereolithography, MPL methods). For applications with the need of metallic components, economical methods are limited. Existing technologies like microdrilling with high resolution up to 2 μm are based on removing material from a bulk with high accuracy but limited 3D geometry capacities. The expenditure of techniques like ablating by electrical spark or etching is only useful for generating functional parts with low batch sizes and is only possible for very easy geometries. For compensation of those deficits the industry tried to decrease the laser sintering layer thickness successfully down to 20 μm by resolutions around 100 μm using the well-known deposition principle of DMLS [Konferenz-Einzelbericht: Advances in Powder Metallurgy & Particulate Materials–2002, Proceedings of 2002 World Congress on Powder Metallurgy & Particulate Materials, Part 4: Compacting, Forming & Die Filling, Orlando, USA, 16–21 June, 2002, Band 4, 2002, Seite 164]. At the Laser Zentrum Hannover e.V. ambitious efforts finding new possibilities in the direction of micro-sintering have lead to a new machine concept combining radical new developments of powder handling in vacuum and new approaches of laser sources using the two-step laser sintering process. The main components are a roll-based mechanism for pre-deposition of the additional materials located in a vacuum chamber and processed by a Yb:YAG-disc laser. Advantages of the roll pre-deposition mechanism is the capacity to use pre-compressed micro powders. In combination with the mentioned disc laser, the laser material processing zone could be limited to a diameter of below 20 μm which establishes new possibilities of micro fabrication.