Lasers have many uses. One way they are used is to cut sheet metal. On mild steel, stainless steel and aluminum, the laser cutting process has high precision, excellent cut quality, very small kerf width and small heat affected zone, and can cut very complex shapes and small holes.
Most people already know that the word “LASER” is actually an acronym for Light Amplification by Stimulated Emission of Radiation. But how does the light pass through the steel plate?
A laser beam is very high intensity light with a single wavelength or color. For a typical CO2 laser, this wavelength is in the infrared part of the spectrum and is therefore invisible to the human eye. When the beam travels the machine beam path from the laser resonator that produces the beam, the beam is only about 3/4 inch in diameter. It can be reflected in different directions by numerous mirrors or “beam benders” before finally being focused on the plate. The focused laser beam passes through the nozzle hole before hitting the plate. A compressed gas such as oxygen or nitrogen also flows through the nozzle orifice.
Focusing of the laser beam can be done with special lenses or curved mirrors, which take place in the laser cutting head. The beam must be focused precisely so that the shape of the focal spot and the energy density in this spot are perfectly circular and coherent, and centered in the nozzle. By focusing the large beam on a precise point, the heat density at this point is very high. Consider using a magnifying glass to focus the sun’s rays on the leaves and how to start a fire. Now consider the concentration of 6 kilowatts of energy at a point and you can imagine how hot that point would get.
High power densities result in rapid heating, melting, and partial or complete evaporation of materials. When cutting mild steel, the laser beam is hot enough to start a typical “oxy-fuel” combustion process, and the laser cutting gas will be pure oxygen, just like an oxy-fuel torch. When cutting stainless steel or aluminum, a laser beam simply melts the material and high pressure nitrogen gas is used to blow the molten metal out of the cut.
On a CNC laser cutter, the laser cutting head moves over the sheet metal in the shape of the desired part, cutting the part from the sheet metal. The capacitive height control system maintains a very precise distance between the tip of the nozzle and the cutting board. This distance is important because it determines the position of the focal point relative to the surface of the board. Raising or lowering the focal point from above, at, or below the plate surface can affect the quality of the cut.
There are many, many other parameters that also affect the quality of the cut, but when all the parameters are properly controlled, laser cutting is a stable, reliable, and highly accurate cutting process.
We provide customers with a one-stop solution for customized laser micromachining services. We have deep research in the field of medical precision laser cutting, and the cutting accuracy can reach 10um.