06 - Hybrid laser-arc welding-1.pdf

Hybrid laser-arc welding prof. Pasquale Russo Spena  Hybrid laser-arc welding Hybrid Laser Arc Welding (HLAW), also known as laser hybrid welding or simply hybrid welding, is a metal joining process that combines laser beam welding and arc welding...

Hybrid laser-arc welding prof. Pasquale Russo Spena  Hybrid laser-arc welding Hybrid Laser Arc Welding (HLAW), also known as laser hybrid welding or simply hybrid welding, is a metal joining process that combines laser beam welding and arc welding in the same weld pool to compensate for their drawbacks or weaknesses as individual technology. The concept of HLAW was first introduced in the 1970s. GMAW is the most popular arc process for HLAW. GTAW and plasma arc can be other alternatives. Laser can be of different sources (e.g., diode, Nd:YAG) P. Russo Spena - Manufacturing and Assembly Technologies - a.a. 2023-24  Hybrid laser-arc welding Main drawbacks of laser welding: - high costs of laser apparatuses - difficult melting of highly reflective or highly thermal conductive metals - small gap tolerance - easy formation of welding defects such as porosity in deeply penetrated weld fusion zones. Main drawbacks of arc welding: - shallow penetration of weld beads in most cases - slower welding speeds - easier formation of humping weld beads at high-speed welding - thermal distortion P. Russo Spena - Manufacturing and Assembly Technologies - a.a. 2023-24  HLAW advantages HLAW process combines the advantages of both processes: - deep and narrow penetration - low heat input - minimal weldment distortion - high possible welding speeds on considerable weld seam volumes - gap-bridging ability - simple feeding of filler material (joint filling is not possible with autogenous LW) - applicable to a wide range of metal alloy systems - time-consuming rework is usually not required - automated process (i.e., precise welds) P. Russo Spena - Manufacturing and Assembly Technologies - a.a. 2023-24  HLAW disadvantages However, there are certain limitations that restrict HLAW: - precise alignment and strict part fit-up are required to maintain weld consistency and quality with HLAW - butt joints with a gap exceeding 1 mm (0.039 in.) are difficult to weld - only for automated applications - short history may be an obstacle for implementing HLAW in applications already using established welding processes. - expensive systems (10 to 50 times than GMAW) - additional safety measures are necessary than GMAW P. Russo Spena - Manufacturing and Assembly Technologies - a.a. 2023-24  HLAW process orientation Schematic of HLAW process orientations. Laser leading Arc leading The choice between these configurations depends on several factors, such as metal base characteristics, power of laser source, and type of arc source. P. Russo Spena - Manufacturing and Assembly Technologies - a.a. 2023-24  HLAW A laser beam is used for laser welding while the arc welding electrode is positioned behind, about 1-3 mm, the laser focal point. The laser beam promotes the keyhole (penetration) while the arc the formation of the weld seam. The Laser-Hybrid welding process is ideal for joining thin-sheet metals up to roughly 3 mm thick in automotive series production: higher welding speed and reduction in filler metal usage. Depending on the thickness of the material, a welding speed of up to 7 m/min can be achieved. P. Russo Spena - Manufacturing and Assembly Technologies - a.a. 2023-24  HLAW P. Russo Spena - Manufacturing and Assembly Technologies - a.a. 2023-24  HLAW Penetration-mode hybrid laser arc welding on steel. hybrid laser arc welding on a carbon steel square butt joint. P. Russo Spena - Manufacturing and Assembly Technologies - a.a. 2023-24  HLAW joint comparison ah36 steel Hybrid welding laser welding arc welding P. Russo Spena - Manufacturing and Assembly Technologies - a.a. 2023-24  HLAW process parameters Main process parameters of HLAW: - individual parameters for laser a) laser power (typically from 200 W to 20 kW) b) spot diameter of the focused beam (typically from 0.2 to 1 mm) - individual parameters for arc a) arc current, voltage, and polarity b) wire feed rate c) electrode (e.g., diameter, composition) d) electrode distance from the work e) shielding gas - travel speed (typically from 1 to 3 m/min) - process orientation - process separation (i.e., the distance between laser focus and electrode wire) P. Russo Spena - Manufacturing and Assembly Technologies - a.a. 2023-24  HLAW torch Example of HLAW heads A specially designed robot holder connects the Laser-Hybrid head to a standard industrial robot. P. Russo Spena - Manufacturing and Assembly Technologies - a.a. 2023-24