Over the past decade, laser cutting has developed into state-of-the-art technology. It is estimate that there are more than 40,000 cutting systems worldwide for high-power metal and non-metal cutting. When including low-power applications. Such as plastics cutting and paper cutting, the numbers are even higher.
Impressive examples of modern laser cutting applications are:
*Cutting of hydro-formed parts and tubes
*High-speed cutting of thin-sheet metal
*Cutting of thick section-material
Developing lasers with higher output powers without sacrifi cing beam quality has been one important goal in the past. Other efforts focused on improving the drive technology of the motion system and enhancing material handling around the cutting table.
Predictions are that laser cutting based on improved cutting speeds, little tool wear and unlimited flexibility will further replace competing technologies. There are market surveys suggesting that the number of fl atbed laser cutter installations will double over the next ten years. In addition, laser manufacturers will address new markets such as cutting tubes and pipes.
Continuous wave (cw) or pulsed laser operations
The highest cutting speeds can be obtained at high power levels in cw-mode operation. Continuous wave (cw) means that the laser power output is constant, without interruption over time.
At high speeds, we use the laser power almost entirely to melt or vaporise the material on the cut front and there is relatively little heat conduction into the base material. However, some of the heat is conducted into the base metal when the cutting direction is reversed or when cutting around a sharp corner. This reduces the feed rate and causes the workpiece to heat up, to the effect that cutting quality deteriorates.
When cutting filigree structures or piercing holes into thicker material.
It can be especially difficult to achieve acceptable cutting qualities with a high-power cw laser. Pulsed processing can produce better cuts under such circumstances. High peak power in the short pulses ensures effi cient heating with an effective removal of hot material from the kerf while low average power keeps the workpiece cool.
The cutting speeds obtainable in pulsed cutting are much lower than with continuous wave (cw) laser beams. We usually reduce average power to some hundred watts in order to achieve a signifi cant increase in cutting quality by pulsing. This often results in cutting speeds that are only 10% of those obtainable in the cw mode. When cutting metallic materials, the peak power generally must be within a range of 1 to 10 kilowatts. And each pulse must be long enough to melt a layer of the cutting front, which is typically 1–3 milliseconds.