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In this work five different laser sources, three different CO2 lasers, a ND-YAG and an High Power Diode Laser (H.P.D.L.) have been used to evaluate the joining quality of PE, PP and PC both in thin films (from 0.01 to 0.1 mm thick) and rigid sheets (from 2 to 5 nmi thick), as well as in particular lap joints (thin films on rigid sheets). Joining process parameters, such as laser power level, welding speed, pressure and type of covering gas, focusing lens, different joint types, using similar or different polymers, have been analyzed to investigate their influence on the quality of the obtained joints.

An excimer laser paint stripping process on metallic surfaces has been investigated, applicable to all those situations, such as adhesive bonding or spot welding, where a localised removal of the surface coating on single parts before assembly could be less expensive and better in quality than the ones realised with traditional methods. This process, due to the properties of the UV laser radiation used, is also suitable for paint stripping on already thermal treated metallic surfaces and plastic composites surfaces. The absence of contact of the laser “tool” with the coating and the easy removal of products formed during the process is another important advantage of this method. Treating radioactive or contaminated parts is also possible, keeping the process in a closed chamber. Several kinds of polymer coatings have been tested for paint stripping experiments applied on aluminium and low carbon steel substrates, with different composition, colours, and thicknesses. The results obtained show that high quality surfaces can be obtained using this treatment, but the processing time is long. These characteristics make the method suitable for treatment of small zones when either high surface quality, or absence of contact, is essential.