Energy coupling and process efficiency in double-focus welding with Nd:YAG

Abstract

Double focus welding is a proven technique to reduce or even to avoid blowholes and porosity in the welding process of aluminium. The application of two focal spots arranged close to each other offers advantages concerning process stability and quality, as well as flexibility. This is a result of a more stable keyhole geometry. The opportunity of designing a task-adapted intensity distribution opens possibilities for the bridging of gaps and the shaping of the weld seam geometry. The central issue of this contribution is to examine the dependence of the energy coupling, thermal efficiency and process efficiency when welding with different spot distances, focus orientations and welding velocities. In the experiments, the energy coupling and the process efficiency were measured and used to calculate the thermal efficiency. It was found that these figures depend on the shape of the keyhole(s) and the welding speed.Double focus welding is a proven technique to reduce or even to avoid blowholes and porosity in the welding process of aluminium. The application of two focal spots arranged close to each other offers advantages concerning process stability and quality, as well as flexibility. This is a result of a more stable keyhole geometry. The opportunity of designing a task-adapted intensity distribution opens possibilities for the bridging of gaps and the shaping of the weld seam geometry. The central issue of this contribution is to examine the dependence of the energy coupling, thermal efficiency and process efficiency when welding with different spot distances, focus orientations and welding velocities. In the experiments, the energy coupling and the process efficiency were measured and used to calculate the thermal efficiency. It was found that these figures depend on the shape of the keyhole(s) and the welding s...