MultiWire cladding optics enable a significant increase in process speed and deposition rates
From plain bearings to rocket nozzles, corrosion and wear protection coatings are an integral part of industrial production. Of particular importance here is the effectiveness and efficiency of the processes used – the goal is to coat as quickly as possible both in a material and energy-efficient manner.
Wire-based laser cladding combines all of these advantages and also supports comprehensive process automation and monitoring. With a material efficiency of 100 percent and comparatively low material costs, the process has proven to be an innovative alternative to conventional MIG/MAG welding.
Another plus point is that, unlike with powder deposition welding, there is no contamination of the environment by the coating material (powder overspray).
Limiting factor: The wire feed
The usual setup for wire cladding is a single lateral wire feed, in which the wire and laser beam meet from different directions on the workpiece surface that is to be coated. However, it is not only the limited deposition rate that speaks against this approach, as the process is then also directional – this means that the cladding process is interrupted after each path because the processing tools have to be set down, reoriented and, if necessary, moved back. .
Processing optics that utilize a coaxial wire feed at least now enable direction-independent and uninterrupted cladding. With this approach, the wire is fed centrally from above and melted using a laser beam split by beam shaping optics. However, the deposition rates are still limited, and the laser power is a maximum of 6 kW, both of which restrict the possible areas of application.
Laserline MultiWire optics: Direction-independent cladding processes with high application rates
Newly developed multi-wire optics from Laserline now enable direction-independent cladding processes with higher deposition rates and/or greater layer thicknesses. This flexible process is made possible by implementing three wire feeds, each feeding wire diameters of up to 1.6 mm, and thereby providing an application rate increase of up to 200 percent.
With a laser output power of 10 kW and a cladding thickness of 1.5 to 2 mm, the MultiWire-based surface deposition rate for steel and nickel alloys is 0.35 to 0.4 m2/h and the material deposition rate is 6 kg/h and 6.5 kg/h, respectively.
Depending on the application, it is also possible to equip the optics with only one or two wire feeds. The new nozzles are compatible with Laserline’s fixed OTS-3 and OTS-5 processing optics, as well as the OTZ-5 zoom optics, and can be swapped in with little effort thanks to their plug-&-play design. The latter also allow maximum freedom in the design of spot sizes and track widths.
Optics monitoring for quality control
Zusätzlich können die Laserline Bearbeitungsoptiken mit Monitoring-Lösungen verbunden werden, um den Gesamtzustand der Komponenten zu überwachen. Durch die Kopplung mit Prozess- und Temperaturüberwachungsmodulen wird zudem nicht nur eine umfassende Kontrolle des Beschichtungsvorgangs, sondern auch eine zuverlässige Qualitätsprüfung ermöglicht.
The occurrence of material defects such as pores, cracks and delamination can thus be avoided to the greatest possible extent. If irregularities do occur during processing, these are registered and the workpiece in question can then be simply rejected. The meltpool width can also be monitored in detail using software-supported infrared cameras. Thanks to their plug-&-play design, these can be mounted quickly and easily on cladding optics such as the OTS-5 and OTZ-5.
Outlook
In addition to classic cladding applications, the MultiWire approach is also suitable for 3D printing applications, making the process an interesting alternative to WAAM (wire arc additive manufacturing).
Customers currently have access to nozzles for cold wire applications, but new hot wire solutions are already being researched – as any feed wires are then preheated, it should be possible to either reduce laser power or achieve even higher deposition rates.
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