Abstract
Laser cladding offers several advantages as low dilution, low thermal influence and distortion of the components and a fine microstructure due to the high cooling rate. Nevertheless the set of laser cladding in the industrial production is nowadays limited to few applications, as the efficiency of laser sources is still too low and the running costs are too high. The absorption behaviour of metal surfaces, as for example steel, towards diode laser (up to approx. 42%) is very high compared to Nd:YAG (approx. 35%) and CO2-Laser sources (approx. 11%), so that some benefits can be expected. One of the disadvantages of diode laser was the low intensity and the difficulty to couple it in a fibre. The development of the last years reached to overcome these boundaries. High power diode lasers are nowadays available till 6 kW and can be coupled in fibres, allowing an easier processing. Investigations regarding laser alloying with high power diode laser confirm the appreciable reliability of this laser class. In order to improve efficiency of laser surface processing the hybrid process plasma-augmented-laser-cladding (PALC) with an Nd:YAG laser source was presented and confirmed that due to the pre-heating of the powder through the plasma transferred arc and the activation of the metallic surface a higher processing velocity (factor three) and efficiency could be reached by summing only one third of the energy with a PTA-equipment. Further more when processing with higher velocity the energy loss due to conductivity decreases so that a further positive increase of efficiency can be depicted. The suitability of fibre coupled high power diode laser for PALC hasn’t yet been investigated, even if the set of this laser type would be very advantageous. In this paper investigations regarding the process design and the necessary set up of the hybrid PALC-process with a 3 kW fibre coupled high power diode laser and wire coating metal are reported.
