CO2 laser technology—the most common laser technology—operates using gas, mirrors and delicate lenses. Because of this, cutting aluminum can be extremely challenging.
Aluminum and other reflective metals, such as copper, brass, bronze, gold and silver, reflect back wavelengths that are directed at them. Most laser cutters align a beam with a flat sheet of material, which means that the reflection can be transmitted back through the delivery optics and into the laser itself. This “flashback” can seriously damage the laser, resulting in thousands of dollars worth of damage, as well as a prolonged repair and maintenance period. Such extensive damage is certainly something to be avoided. In this blog post, we look at various strategies to laser cut aluminum and other reflective metals effectively.
Some manufacturers seek to lessen the risk of “flashback” by placing a non-reflective coating or protective film on the cutting side of the material. However, this non-reflective coating will not completely eliminate the problem. The molten metal produced during the laser cutting process is reflective of itself and could cause just as much damage to the machinery, regardless of any protective film.
Generally speaking, the addition of alloying elements to the metal, particularly aluminum, reduces the reflectivity of the material. This means that the more commonly used 5000 series alloy is easier to cut and process than pure aluminum. However, while alloying can help to reduce the risk of “flashback,” it does not completely eliminate that risk.
Aluminum Cutting System
Because of the risks of laser cutting reflective metals, most modern equipment incorporates a failsafe or aluminum cutting system. This failsafe system detects if too much radiation is being reflected back through the optics and automatically stops the laser before severe damage can be caused. With such a system, as well as proper monitoring, laser cutting reflective metals is possible, but is less efficient.
Fiber Optic Laser Technology
Fiber Optic Lasers (“fiber lasers”) are the most advanced laser cutting technology today. Fiber lasers offer an efficient solution to the difficulties of laser cutting aluminum and other reflective metals. This technology operates using fiber optic cables rather than mirrors and delicate lenses. Because of this, reflective metals do not pose the same threat of damaging fiber laser cutters that they do CO2 cutters. For a more extensive comparison of fiber optic and CO2 laser cutters. It is important to note that fiber laser technology is particularly effective when cutting reflective metals under 5mm in thickness. When cutting thicker materials, cutting speed slows, and cut quality lessens.
Waterjet cutting technology is extremely helpful when it comes to cutting reflective metal sheets that exceed the recommended thickness for fiber laser cutting technology (under 5mm). Waterjet cutters can effectively cut materials of up to 230mm in thickness, exceeding CO2 laser capabilities.
And the Winner Is…
Hopefully, when dealing with the challenges of laser cutting aluminum and other reflective metals, you can make use of these potential solutions to facilitate the process. However, a CO2 laser is not always the most effective or safe choice for such a project. Investing in fiber laser technology presents the best solution to this problem.
At Mainstay, we recently invested in a new Trumpf Fiber Optic Laser Cutting Machine with BrightLine Fiber function. The machine has increased our cutting capability and our capacity as it relates to cutting. We can handle the demands of any project—reflective materials or otherwise. Contact Mainstay to start the conversation.