Fiber laser cutting of aluminum sheets: an experimental investigation into energy ratio of E_M/E_SP

Fiber laser cutting of monolithic lightweight metals like aluminum is commercially well established and is applied extensively in various industries including kitchen appliances, automotive, aerospace, medical and shipbuilding. There are several combinations of commercial laser cutting parameters for aluminum sheets, which are well known to achieve the higher efficiency. This paper investigates the specific point energy and melting efficiency when fiber laser-cutting the 6061 aluminum sheets using 10 bar nitrogen as the assist gas. In this research, four different thicknesses of sheet (0.8, 1.0, 1.5 and 2.5 mm) were cut. In order to minimize the laser energy loss, all sheets were cut using the maximum cutting speed for a variety of powers. The results of this research indicate that the specific point energy (E_SP) increases with sheet thickness. The average kerf width widens with increasing specific point energy. For a given thickness, the theoretical necessary melting energy (E_M) almost is steady as the specific point energy (E_SP) increases. The energy ratio of E_M/E_SP can be considered as a melting energy efficiency criterion. In the range of employed laser cutting condition, the E_M/E_SP is just 0.026–0.118. For a given power density, the E_M/E_SP reduces as the sheet thickness increases. For a given thickness, the E_M/E_SP increases with power density.