Surface pretreatment for adhesive bonding by conventional methods and lasers: a comparative study on human and environmental safety

The article describes the results of identification and analysis of the environmental aspects of metal bonding technology. It was shown that in each of the stages of gluing operations, starting from surface preparation, through preparation of adhesive mass, application of the mass, joining, curing and finishing of the joint, negative aspects for the environment can be indicated. Two particularly problematic stages have been identified: the preparation of the surface before bonding and the preparation of the adhesive mass. These are initial stages, but they are characterised by different forms of human and environmental impact. A modification of the first stage was proposed as an alternative approach. The traditionally used mechanical treatment for steel and chemical treatment for aluminium alloys was replaced by laser treatment. The roughness and wettability of the laser-prepared surface were measured. The numerical results obtained for both the 25HM and X6Cr17 steels investigated, and the 2024 and 5083 aluminium alloys, lead to the conclusion that laser processing can satisfactorily replace environmentally burdensome technology. However, this replacement is not absolutely unconditional. In the following part of the article, it is shown that the use of lasers may involve different environmental aspects and health risks than before. The analysis concludes that new forms of risk should be taken into account when choosing a laser surface preparation technique. However, the best solution, which requires further research, is not only to eliminate chemicals from the surface preparation stage, but also adhesives.