Do you want to know how to get the most bang for your buck? A pulsed laser is your solution. First, what is a pulsed laser? Unlike a continuous wave (CW) laser which is on continuously during the cutting process, a pulsed laser turns on and off at a rapid pace. During these short pulses, energy is released at high peak powers. The pulsing action is what gives the laser most of its advantages. The laser is allowing the material to dissipate localized heat between pulses, creating a lack of a heat affect zone in the material. This results in a cleaner cut with better edge quality.
Oxygen vs. Nitrogen
During the cutting process, two gasses can be used, either oxygen or nitrogen, depending on the type of materials being cut. Metals can be separated into two categories: ferrous and non-ferrous. Simply put, ferrous metals contain iron and non-ferrous metals do not. For the most part, high-pressure nitrogen is used for ferrous metals and oxygen is used for non-ferrous metals, with the exception of aluminum. While oxygen can be used to cut aluminum, it is not ideal because the cut quality dramatically decreases due to the softness of the material.
Other than the choice of gas, the cutting process with a pulsed laser typically remains the same for all materials. The two processes are explained below:
1. Oxygen Assist
- Oxygen amplifies the effect of the laser’s heating of the material, allowing the laser to pierce through quickly. This is especially important in highly reflective material as you want to pierce through before it has a chance to reflect any of its energy back to the laser.
- Benefits: Less used in the process, lower operating costs.
- Limitations: Creates an oxide layer, which may or may not need to be removed before continuing onto the next step of the process. The Oxide layer appears dull and dark and requires chemical passivation or abrasive grinding for removal.
- Example Materials: Copper, Brass , Cold Rolled Steel, Bronze, Silver, and Gold
2. Nitrogen Assist
- Nitrogen is used as a way to blow the molten material through the kerf (cut edge)
- Benefits: Does not create an Oxide layer, leaves a bright and shiny edge on parts like stainless steel and aluminum.
- Limitations: Consumable. A lot of Nitrogen can be used depending on orifice size, the thickness of material, the speed of cutting and laser on time.
- At 2X the pressure of Oxygen, you are going to use roughly 2X the amount of gas to do the same job.
- Example Materials: Aluminum, Stainless Steel, Nickel
Pulsed laser vs. CW laser
The primary benefit of using a pulsed laser as opposed to a CW laser is cost. As stated above, a CW laser needs to be on continuously, meaning that it takes more power to complete a job. An air cooled 450W pulsed laser gives you the ability to operate at 4500W while using only single-phase 220 Volts of AC (alternating current) power. In order to perform a lot of the same tasks with a CW laser, it would take 3000W of laser power operating with 3-phase 480 Volt AC power. Not all facilities are equipped with 3-phase power and would have to pay an expensive fee to wire it in. A pulsed laser, however, only requires single-phase power. The power and performance of a pulsed laser versus a CW, in this case, makes it a far more economical choice from operating costs as well as upfront purchase price. Another way in which operating costs can also be reduced is in terms of the cooling process. In pulse mode in low duty cycle, materials can be air cooled, thus removing the need for an external cooling source.
Another benefit of the pulsed laser is size. A pulse laser is much smaller so fits in the footprint of the machine. Larger lasers, such as the CW laser, have to be on the outside of the machine, which takes up more floor space.
Speed can be a limitation when working with a pulsed laser; however, it only becomes a factor when working with thicker materials. When cutting materials of 16-gauge or less, the cutting time remains the same as that of a CW laser. Materials higher than 16-gauge can take up to double the time to cut.
Though speed can be reduced, the quality of the cut remains high. Ultimately, the CW laser is not capable of the same jobs as a pulsed laser.
Conclusion
The pulsed laser is ideal when it comes to cutting aluminum, brass or copper. The next time you’re looking to make high-quality cuts at a reduced cost, try swapping out that CW laser and go for high peak pulsed power.
Have more insights about using a pulsed laser of some thoughts about these? Join the conversation and leave your comment below.
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