Publicação
Laser welding of morphologically dissimilar thermoplastic structures
| Resumo: | The rising demand for lightweight polymeric structures in automotive, aerospace, and packaging industries drives the development of sustainable joining technologies. Conventional adhesive bonding requires toxic chemi- cals and prolonged curing times, thereby limiting productivity and compli- ance with regulations. Laser transmission welding (LTW) has successfully joined commodity and engineering thermoplastics [1, 2]. This study eval- uates laser transmission welding (LTW) as a solvent-free alternative for bonding polypropylene to low-density polyethylene foam. Thermal analysis of both materials was incorporated in the study. Laser welding experiments incorporating systematic parameter variation (laser power, scanning velocity, clamping force, laser frequency, marking pattern, and laser wobble) aimed to assess joint strength while preserving material integrity. Joints were charac- terized using shear lap testing, scanning electron microscopy, computerized microtomography, and Raman spectroscopy. Among 32 combinations of laser power and scan velocity tested, 15 achieved or exceeded the baseline foam strength (0.90±0.02 N/mm). Morphological analysis revealed typ- ical welding-induced defects—foam cell collapse, void formation, and PP surface damage—but these were minimized through low energy settings. Further experiments confirmed that clamping force significantly enhances joint strength, with values reaching 1.35±0.04 N/mm at 75% deformation, but resulting in a complete collapse of the foam cell structure near the in- terface; while 25% foam deformation yields 0.92±0.03 N/mm with reduced morphological impacts. Optimized marking patterns further improved weld strength, attaining 1.09±0.06 N/mm and facilitating preservation of the materials’ morphology. Conversely, laser frequency and wobble exhibited no significant effect. These findings confirm LTW as a clean and efficient method for joining morphologically dissimilar polymers, offering significant potential for sustainable industrial manufacturing. |
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| Autores principais: | Ferreira, António José de Oliveira |
| Assunto: | Laser transmission welding Thermoplastics Foam Dissimilar bonding |
| Ano: | 2025 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso embargado |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | The rising demand for lightweight polymeric structures in automotive, aerospace, and packaging industries drives the development of sustainable joining technologies. Conventional adhesive bonding requires toxic chemi- cals and prolonged curing times, thereby limiting productivity and compli- ance with regulations. Laser transmission welding (LTW) has successfully joined commodity and engineering thermoplastics [1, 2]. This study eval- uates laser transmission welding (LTW) as a solvent-free alternative for bonding polypropylene to low-density polyethylene foam. Thermal analysis of both materials was incorporated in the study. Laser welding experiments incorporating systematic parameter variation (laser power, scanning velocity, clamping force, laser frequency, marking pattern, and laser wobble) aimed to assess joint strength while preserving material integrity. Joints were charac- terized using shear lap testing, scanning electron microscopy, computerized microtomography, and Raman spectroscopy. Among 32 combinations of laser power and scan velocity tested, 15 achieved or exceeded the baseline foam strength (0.90±0.02 N/mm). Morphological analysis revealed typ- ical welding-induced defects—foam cell collapse, void formation, and PP surface damage—but these were minimized through low energy settings. Further experiments confirmed that clamping force significantly enhances joint strength, with values reaching 1.35±0.04 N/mm at 75% deformation, but resulting in a complete collapse of the foam cell structure near the in- terface; while 25% foam deformation yields 0.92±0.03 N/mm with reduced morphological impacts. Optimized marking patterns further improved weld strength, attaining 1.09±0.06 N/mm and facilitating preservation of the materials’ morphology. Conversely, laser frequency and wobble exhibited no significant effect. These findings confirm LTW as a clean and efficient method for joining morphologically dissimilar polymers, offering significant potential for sustainable industrial manufacturing. |
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