In the laser cladding process a laser beam is generating a melt pool at the surface of the work piece. The cladding material will be supplied via a nozzle to the melt pool. Powder particles will pass the laser beam on the way to the melt pool. The powder particles are moving in a carrier gas. The carrier gas also avoids reactions of the particles with oxygen from the environment. An additional protection gas surrounding the particles stream can be applied in order to improve the protection. The powder particles are supposed to completely melt in the melt pool. By a complete melting of the particles the generation of a dense track can be achieved. The cladding is brought onto the surface track wise. In order to realize particularly high claddings, multilayer strategies are also possible.
Unlike conventional overlay welding, the heat input into the base material is comparably low. Therefore less heat affected zone and less distortion will be caused in the base material by the laser cladding process. In contrast to thermal spraying, laser cladding generates a dense layer which is fused to the base material. This causes a strong bonding in comparison to the thermal sprayed coatings.
By varying the process parameters and selecting different powder materials, a component's surface can be either alloyed or cladded with a carbide or similar coating. Typical deposition rates lie in the region of several cm sq. per minute for layers with a thickness of around 1 mm.
CHARACTERISTIC FEATURES OF LASER CLADDING
The main fields of application are to be found in machine-tool and plant engineering, and engine manufacturing for the aircraft and automotive industries.
Laser cladding can be used for a wide variety of purposes, including the application of wear-resistant or anticorrosion coatings, the repair of worn or poorly machined work pieces, deposition welding of shaped parts, and the complete manufacture of 3-D component.