High-performance laser cladding with combined energy sources

Abstract

In the field of laser additive manufacturing, modern hybrid technologies offer advantageous solutions for combining the high quality level of laser surface claddings with the industry's economical requirements regarding productivity and energy efficiency. The technical approach is to supply energy sources in two fundamentally different ways. First, welding material in the form of wire is directly heated, i.e., by electrical resistance, almost to its melting point and is fed to the process region simultaneously with the laser beam. A newly developed coaxial wire head allows for omni-directional welding operation and, thus, the use of wire even for complex surface claddings as well as layer-by-layer fabrication of metallic parts. Second, an additional energy source is used to heat the substrate in order to compensate for the heat conduction losses. This technical variant is suitable for use with both wire and powder as deposition materials. Additionally, heating and cooling gradients can be precisely adjusted, thus improving the build-up of structures of hard and brittle metallic super-alloys. Currently, deposition rates up to 18 kg/h of metal alloys and metal matrix composites have been demonstrated using these laser hybrid techniques. Industrial applications are, among others, large hydraulic cylinders and tools of the oil and mining industries.