Ablation Drilling of Invar Alloy Using Ultrashort Pulsed Laser

Drilling a hole in Invar alloy is accomplished by using a nanosecond pulsed Nd:YAG laser. However, this process has a few problems, such as heat effect and poor edge quality. Therefore, the ablation properties of the Invar alloy were investigated by using an ultrashort pulsed laser, which is a regenerative amplifier Ti:sapphire laser with a 1 kHz repetition rate, a 184 fs pulse duration, and a 785 nm wavelength. To study the ablation characteristics of the Invar alloy, we measured the ablation shape, width, and ablated depth at the energy fluence of a single pulse. The optimal condition for hole drilling is a z-axis transfer depth of 4 μm, a circular feed rate of 0.2 mm/s, and a pulse energy of 26.4 μJ. A fine circular hole without burrs and thermal damage were obtained under the optimal processing conditions. The ultrashort pulsed laser system is an excellent tool for micro-hole drilling in Invar alloys without heat effects and poor edge quality.