Laser Cutting 101

What is laser cutting and how does it work?

The laser beam is a heat source which can melt metals rather quickly. When the concentrated beam comes into contact with the material, in this case, metal, the beam’s energy is absorbed into the metal, causing it to melt. However, the laser beam is unable to cut through material on its own, which is why the use of an assist gas is necessary. It also helps to push the molten metal out of the cut. These assist gasses can be oxygen, nitrogen, or compressed air, depending on the type of laser cutting machine. 

The three main step steps in laser cutting:

• Laser generation: Source of the laser, either CO2 or fiber laser, which generate a beam of light, resulting into the laser delivery
• Laser delivery: This step occurs in the cutting head, where the laser beam is precisely controlled to a specific speed and power.
• Cutting: Cutting of materials occurs when the laser beam interacts with the metals, generating intense heat and resulting in the removal of material through either melting or expulsion facilitated by the assist gas, oxygen or nitrogen.

The laser cutting process integrates optics, computer-aided design programs and computer-controlled lasers to create highly precise and intricate cuts across materials.

Parameters to achieve the perfect cut:

1. Power
2. Frequency
3. Feed rate
4. Duty cycle
5. Amount of gas
6. Proper setup of equipment
7. Machine maintenance

Test cuts and Fine-tuning parameters

Fine-tuning the laser parameters and performing regular test cuts is a necessary step to ensuring a quality cut. Parameters will vary depending on the type of material being cut, and test cuts will help optimize the laser settings for a perfect cut.

Parameters and how they affect the cut

Power: Measured in watts and refers to the amount of energy being delivered from the laser and to the material being cut. Higher power consumes more energy, but performs faster and efficient cuts through a variety of materials. More power is needed to cut through thicker materials, but is more likely to deliver a clean cut.

Feed Rate: The feed rate is interchangeable with speed. Specific feed rates, or speeds, produce different cuts. Increasing the feed rate will tighten the focus range, emphasizing the importance on properly setting up and prepping the laser and its optics, but increasing it too far increases the risk of cutting instability. There is a small range that can be used to achieve the best cuts at the highest efficiency.

Frequency: Frequency is a method of pulsing or turning the beam on and off at a high rate. This is either measured in hertz, or pulses per second, and may have the ability to turn on and off thousands of times per second, depending on the machine.

Duty Cycle: Duty cycle controls the number of pulses per second, and works in close proximity with the frequency. This parameter allows for cooling in between pulses. Less duty gives more cooling time, while adding duty adds heat.

Assist Gasses: Assist gasses are a secondary stream of inert or non-reactive gasses used in combination with the primary CO2 laser beam during its cutting operations. Standard air will not work for all materials and could cause discoloration or reduces success rates.