Product Code: ICAL05_P573

A Method to Improve Efficiency and Reliability of Laser Cladding Processing by Plasma-Augmented-Laser-Cladding
Authors:
Johannes Wilden, TU Ilmenau; Ilmenau Germany
Jean Pierre Bergmann, TU Ilmenau; Ilmenau Germany
Markus Dolles, TU Ilmenau; Ilmenau Germany
Presented at ICALEO 2005

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 is presented and confirmes 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 can 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.
Further more the suitability of fibre coupled high power diode laser for PALC hasn�t will be investigated and reported in this paper. The coating material was fed in form of wire. The process setup and the geometric conditions will be pointed out. The investigations confirmed the assumption that cladding metal surfaces with PALC shows a higher efficiency than conventional laser process. In this case PALC allows a better processability, as well. Due to the additional energy source the processes speed is raised of factor three so that the losses caused by heat conduction into the substrate can be further minimized.