Fully closed-loop semi-automatic laser cladding cell in a serial production of small tools

Various small metal forming tools utilized in hot extrusion of non-ferrous metals and alloys are susceptible to severe wear and sticking at high temperatures, thermal softening and fatigue leading to premature failures and extra interruptions in production due to frequent tool replacements. Laser cladding combined with appropriate material selection proved to be a suitable technique to increase the tool life significantly. To implement this, a fully closed-loop semi-automatic laser cladding cell was developed. The procedure consists of induction unit for preheating and Nd:YAG laser for cladding, which both are adaptively controlled. In order to clad more than one surface of the tool, the most flexible way to do the cladding was to keep the laser and powder nozzle stationary while the robot manipulates the tool. Due to small dimensions of the tool and cooling channels beneath the surface to be clad, heat accumulates largely during the cladding process, which leads to increasingly higher levels of dilution and lower levels of hardness between different surfaces. Using adaptively controlled laser power, surfaces with equal dilution and hardness were obtained. With adaptively controlled induction heating unit, preheating phase of the process was suppressed down to minimum, and accuracy as well as repeatability was improved substantially compared with conventional preheating methods, which are also impractical in serial production.