20CrMnTi, commonly used material for spiral bevel gears, is a kind of good carburizing steel with high impact toughness, high strength and good fatigue resistance.

In the process of femtosecond laser ablation, the energy absorption is nonlinear. The mechanism of femtosecond laser energy intensity in different scales affects the material removal. The removal mechanism of femtosecond laser is different from that of nanosecond laser processing. It mainly completes ablation through the interaction of photon electron lattice system, which avoids the generation of thermal damage from the source.

The picture shows the femtosecond laser ablation mechanism of gear material. When the Gaussian pulse beam acts on the surface of the gear material, because the pulse of the femtosecond laser is very short, the electrons on the surface of the material absorb the laser photon energy through bremsstrahlung, which leads to the collision and coupling heating of the electron and photon, and the temperature of the electron will rise rapidly; the energy is transmitted to the lattice through the electron lattice coupling When enough energy is absorbed, the material will melt, evaporate and vaporize. When the equilibrium temperature of the electron and lattice of the gear material reaches the melting temperature of the material, the metal will be ablated, and finally the machining allowance of the gear material will be removed.