Laser Welding of Copper Using Multi Mode Fiber Lasers at Near Infrared Wavelength

Abstract

Due to the increasing electrification of automotive drives and the expansion of decentralized renewable energy generation, the consumption of copper for the fabrication of electrical components such as electric motors or conducting paths increases. To join these components, laser welding is more frequently used since it represents a flexible and fully automatable joining process. Because of the high thermal conductivity, the low absorption coefficient for infrared wavelength of common laser beam sources and the resulting limited process efficiency, welding of copper alloys represents a major challenge for laser assisted processes. In this paper, experimental investigations are presented to identify arising process limits during laser welding of pure copper materials with multi-mode fiber lasers at near infrared wavelength depending on the applied laser power and welding velocity. In addition, a potential stabilization of the welding process by shielding gas support was examined. Further investigations were focused on the influence of shielding gas on the molten pool geometry.

Advances in macro-scale laser processing

“…Consequently, these ejections as well as pores can be avoided by a proper modulation of the laser power, which counteracts the formation and stability of bubbles [83]. Other investigations confirmed the influence of the laser power and welding speed, while an important influence of the shielding gas (Helium and no shielding gas were compared) was shown [144]. The negative influence of ambient air instead of Helium can be understood qualitatively from the changes in the melt pool cross section with a narrow throat and the increased weld depth, which both increase the probability for melt ejection.…”

“…The high reflectivity complicates the laser process, so that beam sources with high intensities or wavelengths in the visible range must be used. [55,144]…”

Measuring the effects of a laser beam on melt pool fluctuation in arc additive manufacturing

“…This produces a lot of qualitative data that, although valuable, can prove quite difficult to measure (and communicate to others). A common way to display findings from HSI is to present a single frame or sequences of frames (Fathi et al , 2010; Heider et al , 2013; Liebl et al , 2014; Moradi et al , 2013), which can be useful to describe observed phenomena, e.g. droplet shape and trajectory.…”

Copper Welding with High‐Brightness Fiber Lasers

“…Another issue in the copper welding process is instability when welding at low speed [1]. For a welding speed of less than 5 m/min, we typically face problems with weld instabilities such as spatter, blowholes and irregular weld seam surfaces.…”