Abstract: The laser machining equipment for etching grooves in a wall of a mechanical part, in particular of a connecting rod for a spark ignition engine, is provided with a fibre optic laser device and arranged to supply laser pulses. The fibre optic laser device is controlled so that said laser pulses have a peak power of more than 400 W and at least two times greater than the maximum mean power of said laser device and in that the duration of said laser pulses is below or within the nanosecond range (1 ns to 1000 ns). According to a first embodiment, the fibre optic laser device is controlled in a quasi continuous wave (QCW) mode. According to a second preferred embodiment, the fibre optic laser device is controlled in a Q-switch mode. The selected operating modes increase machining efficiency and produce a groove with an optimum transverse profile, particularly with a small mean radius of curvature at the bottom of the groove which then allows precise subsequent fracturing of the mechanical part with less force.

Abstract: A laser machining equipment for etching grooves in a wall of a mechanical part, or in a connecting rod for a spark ignition engine, includes a fiber optic laser device arranged to supply laser pulses. The fiber optic laser device is controlled so that laser pulses have a peak power of more than 400 W and at least two times greater than maximum mean power of the laser device, and duration of the laser pulses is below or within the nanosecond range of 1 ns to 1000 ns. The fiber optic laser device can be controlled in a quasi continuous wave (QCW) mode, or can be controlled in a Q-switch mode. The selected operating modes increase machining efficiency and produce a groove with an optimum transverse profile, particularly with a small mean radius of curvature at a bottom of the groove which then allows precise subsequent fracturing of the mechanical part with less force.

Abstract: A laser machining method includes A) generating, by a laser source, a laser beam having an initial wavelength between 700 and 1200 nanometers of laser pulses; B) doubling frequency of one part of the laser beam by a non-linear crystal; C) varying power throughout each emitted laser pulse so that the power profile has a maximum peak power or part of the pulse with a maximum power in an initial sub-period, and throughout an intermediate sub-period of longer duration than the initial sub-period, a lower power than the maximum power. The maximum power value is at least two times higher than the mean power throughout the laser pulse and an increase time to maximum power from a start of each laser pulse is less than 0.3 milliseconds. The machining method can concern welding highly reflective metals, copper, gold, silver, or an alloy including one of these metals.