At the end of 1974, Gnanamuthu of ACVO EVERETT RES LABINC put forward the world’s first laser cladding patent US3952180A, which opened the curtain of basic research work on laser cladding technology.
With many advantages such as low dilution rate, low heat input, and a wide range of materials, laser cladding technology has evolved many types in the process of industrial application and is widely used in various fields of additive manufacturing, re-manufacturing, and surface engineering.
According to the type of material to be laser melted and the form of coupling between the material and the laser beam, the common laser melting technologies can be divided into coaxial powder feeding laser melting technology, side axis powder feeding laser melting technology (also called lateral powder feeding laser melting technology), high-speed laser melting technology (also called ultra-high-speed laser melting technology).
Coaxial Powder Feeding Laser Coating Technology
Coaxial powder feeding laser cladding technology generally uses a semiconductor fiber output laser and a disk-type airborne powder feeder. The cladding head adopts a circular spot scheme with central light output, a circular powder feed or multiple powders feeds around the beam, and a special protective air channel, where the powder beam, light beam, and protective airflow intersect at a point. The melt pool is formed at this focal point during the cladding operation, and the cladding layer is formed on the surface of the workpiece with the relative movement of the cladding head and the workpiece.
Side Axis Powder Feeding Laser Cladding Technology
Side axis powder feeding laser melting technology is also called lateral powder feeding laser melting technology, which generally adopts semiconductor direct output laser or semiconductor fiber output laser and gravity powder feeder, and the melting head adopts rectangular spot + side axis broadband powder feeding scheme. When the cladding head works, the alloy powder is delivered to the workpiece surface for presetting through the powder feeding nozzle. With the relative motion of the cladding head and the workpiece, the rectangular laser beam scans the preset alloy powder and melts it to form a molten pool, which forms a cladding layer after cooling.
Ultra-high Speed Laser Cladding Technology
Ultra-high-speed laser melting technology is a new type of laser melting technology developed by Fraunhofer Institute for Laser Technology in Germany, which started to be promoted and applied in China in 2017. The ultra-high-speed laser melting technology adopts a semiconductor fiber output laser or fiber laser with better beam quality, a precision-designed high-speed laser melting head and a motion mechanism with high rotational speed or moving speed. The coupling of the laser beam with the powder beam and the inert gas flow is precisely designed so that part of the laser energy is used to heat the powder beam while the other part of the laser beam penetrating the powder beam heats the substrate, and the powder is melted or heated to a very high temperature before it enters the melting pool, thus shortening the time required for powder melting. Laser cladding up to 2m/min).
