Advancing Laser Profile Welding
Laser profile welding is well-established as offering higher throughput speed, reduced scrap and improved weld metallurgical characteristics over established methods. Now, advanced laser-based systems are available offering functionality that makes the process itself more stable and highly automated. This article reviews one particular laser-based sub-system, the Coherent Profile Welding System (PWS), which offers a unique mix of capabilities and features that enable cost-effective, high throughput processing in demanding production environments.
The Coherent Profile Welding System
The Coherent Profile Welding System (PWS) leverages the inherent advantages of laser welding, together with several advanced features, to deliver high quality, rapid throughput, tube and profile welds on a variety of metals. The system combines a CO2 or fiber laser source, beam delivery system, process sensors, precision motion, and powerful software to offer an unmatched combination of weld quality, ease-of-use and operational flexibility.
The Coherent PWS is available with an industry proven Coherent DC 0xx CO2 laser, which is well-established as delivering a stable, high quality process on most materials. Alternately, another option is the Coherent HighLight-FL fiber laser with its special Adjustable Ring Mode (ARM) technology. The unique beam output characteristics of this source enable more precise control over the manner in which power is delivered at the workpiece than can be achieved with traditional fiber lasers. The Coherent PWS, configured with the FL-ARM, has already proven to be particularly advantageous with aluminum and various types of steel, especially, stainless steel.
The dimensions of the focused laser beam are typically small compared to the variations that are normally encountered in gap position during profile welding. Since the focused laser beam position must be precisely maintained with respect to work piece gap, “seam tracking” is essential in a profile welding system. Because of this, the Coherent PWS contains an integrated process sensor for welding gap detection and tracking. This sensor provides feedback that is used by the system’s precise, fast response linear actuators to always maintain accurate (within a few ten microns) laser beam positioning with respect to the gap. All this is accomplished automatically, and can be achieved at weld speeds as high as 60m/min.
Another important productivity feature of the Coherent PWS is an automatic system height focus capability. This enables the system to automatically adjust after a changeover to a new tube diameter or to compensate for part-to-part tolerance variations in actual tube diameter. This reduces setup time, speeds changeovers, and makes welding results more independent of material tolerances and less operator dependent.
The Coherent PWS also implements a new “reverse welding” feature. This eliminates any gap in the weld seam when the system is stopped and then subsequently restarted. Again, this improves operational flexibility and can reduce scrap rates. And, because the system is Industry 4.0 ready, it can be easily integrated within modern manufacturing plants structures.
A final system feature worth mentioning is the ability to generate a specific, predefined interior weld bead, as required by the application. This further extends system flexibility and improves results, while also reducing manufacturing costs.