Feasibility of Fillet Edge Weld Using Laser Wobble Technique
Abhishek Das, Tom Dale, Iain Masters, Widanalage Dhammika Widanage
Abstract
In many industrial applications, especially for automotive, aerospace and electronics, laser welding is the preferred joining process due to its high flexibility, short process time and high precision. In conventional single-mode laser welding, the laser beam is fine (typical spot diameter 10 – 40 µm) producing a very narrow weld profile. Wobbling or oscillating the laser beam ensures the weld width and depth of penetration can be achieved in a controlled manner. The wobble technique is most useful for highly conductive and reflective materials as it helps to reduce the spatter formation, back-reflection and instability with the laser. Joining with an overlap configuration created using the wobble technique have been most commonly investigated. But the fillet edge weld is considered more useful for sealing applications without the need for additional filler material. This paper investigates the feasibility of producing fillet edge welds, using the wobble technique, to join 0.3 mm thin aluminium to 1.5 mm thick aluminium sheet. A 1.0 kW CW IR laser was used to produce the fillet edge welds aiming for both joining and sealing applications. The effects of process parameters including laser power, welding speed, wobble amplitude and wobble frequency were studied to evaluate the weld quality. Joint strength and weld microstructural features including penetration depth and interface width were evaluated as indicators of weld quality. The relations between the input laser process parameters and output quality indicators were identified and the weld quality was classified into under-weld, good-weld and over-weld categories. In the case of the good-weld condition, average lap shear strength was around 418.64 N. The results suggested that preferred penetration depth and interface width can be obtained by controlling the laser power, welding speed and wobble amplitude. Overall, this paper demonstrates the feasibility of obtaining good fillet edge joint using laser wobble technique.