Control of temperature fields and melt formation in laser transmission welding using adapted laser wavelengths
- The usage of laser transmission welding of polymers as a joining technique in industrial applications is often limited by the optical properties of the joining partners and the limited gap-bridging capability. By using alternative laser wavelengths or multiple beam sources it is possible to adjust the radiation to the properties of the materials and increase the weld seam quality. Especially for scattering materials, parts without specific laser absorbing additives and in applications where relatively large gaps occur due to manufacturing tolerances of the parts, adapted wavelengths can lead to improved results. In this work, the gap bridging during quasi-simultaneous laser transmission welding is investigated in welding experiments and thermomechanical FE-simulations. Usage of a laser wavelength in the range of 2.0 μm is found to be beneficial in terms of gap-bridging, compared to usually applied diode or solid state lasers emitting at about 1 μm due to the higher intrinsic absorption in unmodified thermoplastic materials. This leadsThe usage of laser transmission welding of polymers as a joining technique in industrial applications is often limited by the optical properties of the joining partners and the limited gap-bridging capability. By using alternative laser wavelengths or multiple beam sources it is possible to adjust the radiation to the properties of the materials and increase the weld seam quality. Especially for scattering materials, parts without specific laser absorbing additives and in applications where relatively large gaps occur due to manufacturing tolerances of the parts, adapted wavelengths can lead to improved results. In this work, the gap bridging during quasi-simultaneous laser transmission welding is investigated in welding experiments and thermomechanical FE-simulations. Usage of a laser wavelength in the range of 2.0 μm is found to be beneficial in terms of gap-bridging, compared to usually applied diode or solid state lasers emitting at about 1 μm due to the higher intrinsic absorption in unmodified thermoplastic materials. This leads to increased temperatures in the transparent joining partner and therefore greater thermal expansion. Furthermore the radiation shows an increased penetration depth in carbon black filled, laser absorbing materials, also leading to increased thermal expansion and improved gap bridging. The wavelength of 2.0 μm is also found to improve the strength of weld seams when turbid materials or materials with scattering additives are used as laser transparent parts, since scattering at small particles is strongly wavelength dependent, so the longer wavelength features better control of the resulting intensity distribution in the joining zone.…


| Author: | Andreas Schkutow, Thomas Frick |
|---|---|
| URL / DOI: | https://wlt.de/lim/Proceedings2017/Data/PDF/Contribution72_final.pdf |
| Parent Title (English): | Proceedings of LiM 2017 |
| Publisher: | Wissenschaftliche Gesellschaft Lasertechnik e.V. |
| Document Type: | conference proceeding (article) |
| Language: | English |
| Date of first Publication: | 2017/06/26 |
| Release Date: | 2025/02/26 |
| Tag: | laser transmission welding; adapted wavelength; melt pool geometry; gap bridging |
| Pagenumber: | 9 |
| Konferenzangabe: | WLT LiM - Lasers in Manufacturing Conference, 2017, Munich |
| institutes: | Fakultät Maschinenbau und Versorgungstechnik |
| Institut für Chemie, Material- und Produktentwicklung | |
| Research Themes: | Materialien & Produktionstechnik |
