- Processing of new Fe-, Co- or Ni-based alloys for high temperature and/or wear-resistant and mechanical fatigue-resistant applications.
- Repair with alloys with difficult welding properties, and that are highly susceptible to cracking.
The addition of material to overlay and repair is a procedure whereby a melted material is added to a certain area or surface of a base material or substrate. In repair applications, the filler material is usually similar to the base material, while in overlay processes, a different material is used to make the substrate more resistant to wear and/or corrosion. In the latter case, the least possible dilution of filler material with the base material is sought in order to obtain a differentiated chemical composition in the weld metal.
At LORTEK two technologies are available to overlay and repair with filler material. One is laser overlay or Laser Cladding (LC) and the other is electric arc overlay. The former is a metal deposition process that uses a laser source to generate a concentrated beam that melts the material, which is dispensed through a powder feeder to the nozzle. In the second case, a controlled electric arc generates the necessary energy to melt the filler wire. In both cases, material is added through the overlapping of beads in one or several layers on a flat or 3D shaped substrate, with a high deposition rate (up to 2.5 Kg/h for laser cladding, and up to 4 Kg/h with electric arc).
These technologies permit the use of a wide variety of high-quality commercial materials in the form of powder or wire. Alongside raw material manufacturers, with which LORTEK has partnerships, suitable mechanical properties can be obtained, and sometimes it is even possible to improve the wear and/or fatigue resistance in a wide range of service temperatures and complex operating conditions. These processes also permit obtaining gradual composition or multi-material components.
One of the advantages of the laser cladding process is that it permits controlling the energy density provided and the laser beam diameter, to effectively control the heat input per unit of area, and obtain defect-free filler, with low dilution and low thermal affectation of the substrate.
On the other hand, the electric arc overlay technology is a more economical process due to the lower cost of the filler material, of the equipment, and the higher deposition rate, although the dilution level and the residual stress and distortion are much higher than that achieved by means of laser cladding.
With material overlay, the working life of components such as punches and dies, and other tools can be increased. It can also be used to make partial repairs in localized areas of large or high-value parts both during manufacture and during maintenance operations.
Depending on the final application, similar or improved mechanical properties, with respect to those of the base material, can be obtained, providing that the filler material, the process parameters and manufacturing route have been adequately selected. LORTEK’s knowledge in terms of materials, advanced characterization and process, permits 360º accompaniment for the industrial implementation of these processes. Combined with the advanced automatic non-destructive inspection techniques developed by LORTEK, this guarantees the final quality of the product and of the filler material, providing the components with enhanced functionalities.
LORTEK has three solid state laser sources for laser overlay: a 6 kW disc laser, a 3kW Nd-YAG laser, and a 1kW fibre laser. It also has a semi-conductor source: a 3kW diode laser. This wide range of wavelengths and power permits processing a broad gamut of materials, using the most adequate laser for each specific application. It also has different headstocks with fixed or floating optics, which permit varying the laser spot during the process, as well as incorporating ports for on-axis sensors or camera to monitor the melted bath, or to measure the temperature. The laser beam is guided to the headstock by different diameter optical fibres.
The powder is provided through powder feeders from two heated hoppers with two types of nozzles: coaxial for standard powder, and three-jet nozzles with carbide inserts for the different applications and degrees of accessibility required. Different specialized CAM software packages are available to generate trajectories for direct deposition processes, in which the virtualization of kinematics, headstocks and nozzles, and the execution of simulations are possible.
With respect to electric arc overlay equipment, LORTEK has the following equipment:
Challenges to be faced in the coming years: