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Speed vs. Power

Understanding the relationship between power and speed is an essential part of being able to produce high quality cuts and engravings, as well as optimizing your settings to finish jobs faster.

Always pay attention to units of distance and time when entering Speed settings

When entering Speed values recommended by your laser's manufacturer or other LightBurn users, make sure to use the same units of distance and time as those from the recommendation, or to convert the values to your preferred units.

A given number of millimeters per second is much faster than that same number in millimeters per minute. Mixing up units can lead to reduction in power output due to unexpectedly high speeds, or excessive power output — and even fire — due to unexpectedly slow speeds.

Change your displayed units in the Units and Grids tab of the Settings window. LightBurn automatically converts any existing values when you switch between units.

Speed vs. Power Basics

The two primary settings controlling the depth of a cut or the darkness of an engraving are power and speed.

Power controls the laser's intensity. Higher powers allow you to cut deeper or make darker marks for engravings, but at the cost of potentially charring or melting edges, making excessive smoke, and making a wider kerf.

Speed controls how fast the laser moves. Lower speeds will deliver more power and heat to the material by staying in one point longer. Higher speeds can complete a job faster, but will require higher power. High speeds can also make existing mechanical issues more apparent.

material test example

The image to the right shows a simplified example of a test grid similar to what LightBurn's Material Test Generator produces. This example helps show the relationship between speed and power:

  • In the top left corner, where the speed is high and the power output is low, the mark is faint and barely visible.
  • The marks get darker both going to the right (increasing power) and going down (decreasing speed).
  • In general, to make darker marks or deeper cuts, you can increase power, decrease speed, or do both.

You might also have noticed that the bottom right corner isn't noticeably darker than the circled mark. Beyond a certain point, increasing power or decreasing speed has limited usefulness. In this example, the circled mark would get similar results to a slower and higher power cut, but faster and with reduced power consumption.

For a more realistic example, see the picture below showing an actual material test. As with the example above, the marks get darker and deeper with increasing power and decreasing speed.

material test example 2

Optimizing Cut Settings

The best power and speed combination will depend heavily on not only your laser and material, but what you're doing.

  • For image engraving, especially with CO2 lasers, going slowly at a low power typically gives the best results. See 5 Steps to Perfect Image Engravings for more information.
  • When cutting, it's best to do use LightBurn's Material Test Generator to find a setting that cuts through the material cleanly without scorching. Look for the lowest power and highest speed that cuts through reliably.
  • If you're having issues with scorching or melting the edges of your material, try using multiple passes rather than continuing to increase power.

TODO: Image of lines cut at different power/speed combinations

For more help using LightBurn, please visit our forum to talk with LightBurn staff and users, or email support.