Abstract
Laser cleaning is a rapidly advancing method gaining attention and finding new applications. Compared to other surface cleaning methods, an advantage is that no sand or chemicals are used in the process, only energy. Noise, dust and waste are therefore significantly reduced, making it a more HSE friendly method.
Cleaning lasers are typically 1064 nm infrared Nd:YAG (neodymium-doped yttrium aluminium garnet), pulsed at 10 – 100 kHz, with power outputs ranging from 50 to 5000 W. Cleaning rate (m2/h) has so far been lower than blast cleaning, but more comparable to power tool cleaning (e.g. disc grinder, steel brush, needle gun). Most cleaning lasers will not provide surface roughness, but that can be achieved with a more powerful instrument. New instruments are rapidly introduced. This study aimed to investigate the surface cleanliness achieved by laser cleaning. Various surfaces, including coated, salt contaminated and corroded, were cleaned with 300 W and 2000 W lasers. In addition, fumes from the cleaning process were collected and analysed, to evaluate potential HSE issues with laser cleaning. Temperature changes during the process were measured on the surface and on the backside of the panels.
Following the cleaning process, the surface composition and structure were investigated by electron microscopy, and an epoxy was applied to evaluate coating adhesion. The more powerful laser had of course a higher cleaning rate, but both lasers were able to clean the surfaces. Surface composition analysis indicated that high temperature oxidation had occurred, which may be beneficial with respect to corrosion protection [1,2]. The epoxy coating demonstrated good adhesion on the cleaned surfaces, although the surface profile was little affected by the laser [3]. Fumes from the cleaning depended on contaminants and coatings present on the surface.