Fibre lasers belong to the group of solid-body lasers and produce a particularly small focal diameter. This allows that their intensity is up to 100-times higher than the one of gas lasers with the same average power emitted. It is particularly suitable for the metal marking by annealing, for the metal engravings and for the marking of plastics with a broad range of contrasts. Generally, fibre lasers are maintenance-free and they stand out for the long service life of the laser, of at least 25,000 hours. It is a suitable technology for metals, coated metals and plastics. Some researchers have studied the fibre laser cutting on AA221 aluminium alloys. The morphological features of the cutting surface were examined at the optical microscope and the characteristic sizes were measured by a Vernier pliers. An accepted cut with smooth surface and the presence of minor slags can be reached through the aid of appropriate parameters. The cutting surface has been characterized by three zones with different streak models that are HSZ on the top, VSZ in the middle and OSZ at the bottom. The OSZ oblique zone is the hardest of the cutting surface. The upper HSZ part is mainly caused by the gas flow because most part of the liquid metal in this zone is pulsed down, while in the VSZ middle and in the lower OSZ zone they are determined by the interaction of the gas pressure and the other forces exerted on the melting bath. Increasing the energy advantages of the laser process in order to improve the cutting quality while decreasing the OSZ fraction in the cutting surface, an excessive energy on the laser process would increase the quantity of slags and would diminish the cutting quality. Therefore, there is an optimal energy interval of the laser process in order to obtain an acceptable cutting that turns out to be equal to 25-35 J/mm.
Source: Cong Chen, Ming Gao, Ming Jiang, Xiaoyan Zeng, «Surface morphological features of fiber laser cutting of AA2219 aluminum alloy», The International Journal of Advanced Manufacturing Technology, pp. 1-8 (2016). DOI: 10.1007/s00170-015-8271-z