Advantages and Limitations of Lamp Pumped Nd:YAG Lasers for Micro-cutting of Shape Memory Alloys

This paper deals with laser micro-cutting of shape memory alloys, which is currently used in the manufacturing of micro components such as miniaturized actuators in robotic systems and coronary stents in medicine. The influence of the laser pulse energy on the characteristics of micro-cuts produced in 400 μm thick sheets of nickel-titanium alloy, by means of a flash lamp pumped Nd:YAG laser, was investigated. Experimental results showed that micro-cuts produced using this laser are characterized by a narrow kerf width, cut surfaces with a high perpendicularity and low roughness, and the absence of dross in the bottom side when the pulse duration is reduced to 0.25 ms. In particular, it was found that the minimum kerf width is approximately 60 μm and the Ra values of cut surfaces are in the range of 1-2 μm. Since a single laser scan is sufficient to produce micro-cuts, when using such lasers it is also possible to achieve shorter machining times than the ones obtainable by ultra short pulse lasers, which still have the advantage to induce negligible heat affected zones.