Overview of Laser Cutting for Sheet Metal
Laser cutting can be a viable, effective, and cost-efficient option for sheet metal fabrication. Laser equipment is unique in that laser cutters do not make direct contact with the material, they use high-energy power sources, have tighter cutting tolerances, and are generally automated to maximize precision. A major benefit of laser cutting machines is they can produce complex contours. However, the quality depends on the operator's expertise and using the appropriate type of technology for the desired result.
Laser cutters work by firing a concentrated stream of photons onto a precise area of the sheet metal, which trims excess material and shapes the metal into the desired design. Laser cutting can be very effective in cutting various grades of steel, such as stainless and carbon steel. However, they can be less effective on light-reflective or heat-conductive metals, like aluminum or copper.
Types of Lasers
The most common types of laser cutters used in manufacturing are:
Nd:YAG (neodymium-doped yttrium aluminium garnet; Nd:Y3Al5O12). This is a crystal that is used as a lasing medium for solid-state lasers. These are one of the most common types of laser, and are used for many different applications. Nd:YAG lasers operate in both pulsed and continuous mode. Nd:YAG lasers are used in manufacturing for engraving, etching, or marking a variety of metals and plastics, or for metal surface enhancement processes. They also are extensively used in manufacturing for cutting and welding steel, semiconductors and various alloys.
CO2: A carbon dioxide laser is more powerful than Nd:YAG lasers and use gas instead of a crystal for focusing light. Carbon dioxide lasers are the highest-power, continuous wave lasers currently available. The CO2 laser’s gas mixture contains carbon dioxide (CO2), helium (He), nitrogen (N2), and possibly some hydrogen (H2), water vapor and/or xenon (Xe). Such a laser is electrically pumped via a gas discharge, which can be operated with DC current, with AC current (e.g. 20–50 kHz) or in the radio frequency (RF) domain (RP Photonics Encyclopedia.)
There are many different methods used in cutting with lasers depending on the material being cut. Some of the methods are:
Melt and blow
Thermal stress cracking
Stealth dicing of silicon wafers
Configurations of Cutting Machines
There are three typical configurations of laser cutting machines used in manufacturing, which determine the way the laser beam is moved over the material to be cut or processed:
Moving material lasers have a stationary cutting head and move the material under it. This method provides a constant distance from the laser to the workpiece. It requires fewer optics, but requires moving the workpiece, which tends to be the slowest method.
Hybrid lasers provide a table, which the material moves in one axis (usually the X-axis) and the head along the shorter (Y) axis. The result is a more constant beam delivery path.
Flying optics lasers feature a stationary table and a cutting head (with laser beam) that moves over the workpiece in both of the horizontal dimensions. Flying optics cutters keep the workpiece stationary during processing and often do not require material clamping. The moving mass is constant, so dynamics are not affected by the varying size of the workpiece. Flying optics machines are the fastest type, which is advantageous when cutting thinner workpieces.
Laser cutting involves removing material to shape a product. Most laser cutting systems use CNC parameters, which control the level of precision and cutting speed. CNC programming can also regulate power output, enabling the laser to adjust to contours and material thicknesses.
Research and Development
Ongoing research is being conducted to improve the quality and cleanness of laser cutting technology. As these systems continue to improve, more applications likely will emerge.