What do laser parameters mean?

There are many different laser parameters including power, speed, ppi, Hz, pass, Air Assist and z-offset, but what do they actually mean? This page offers a brief explanation of the different parameters.

The most important settings in the material database are the power and speed laser parameters, which can be set as a percentage between 0 and 100%.

The Power laser parameter describes the output power of the laser. 100% is the maximum power. A higher power is needed for dark wood or stamp engravings, while lower values are used for materials such as paper.

The Speed laser parameter describes the movement of the laser head. Fast speeds lead to short exposure times, while slow speeds lead to long exposure times. For example, large-scale engraving of TroLase materials are engraved at high speeds between 80 and 100%, but for photo engravings with lots of detail on wood, the speed should not exceed 10%. This setting also affects the quality of the finished laser cut.

Note that laser cutting and engraving speeds are not comparable, cutting is slower than engraving (a "high" cutting speed is 10%).

The PPI parameter (=pulses per inch) determines how many laser pulses per inch are used for the laser engraving. This should be the same or a multiple of the dpi selected in the print setting to ensure that you achieve a good result. If you set this parameter to "Auto," JobControl automatically determines the optimal resolution of the laser pulses.

During the laser cutting process, Frequency is a decisive parameter and is given in Hz (=Hertz). It specifies the number of laser pulses per second. In a CO₂ laser machine, the value can be set within a range of 1,000 to 60,000 Hz. For example, if you want to achieve a smooth edge when acrylic laser cutting, you need higher temperatures, thus meaning this value is set to at least 5,000 to 20,000 Hz. On the other hand, laser cutting wood a low frequency of 1000 Hz is necessary in order to achieve the brightest possible cutting edge (for example).

The Pass parameter determines the number of engraving or cutting passes required. With some materials it can be advantageous to laser engrave with a lower power and higher speed, and then repeat this process several times. This results in less stress on the material per pass. This approach is suitable for relief engraving.

Every material reacts differently to a laser process. During laser engraving and laser cutting, the supply of compressed air can significantly influence and improve the results. Furthermore, Air Assist protects the lens against damage as it prevents dust from adhering to it. The Air Assist is switched on and off automatically by the software. If the Trotec Laser is delivered from the factory with Air Assist and pump installed, the two units are directly integrated in the enclosure. Trotec laser systems are equipped with Air Assist; optional gas-kit available for connection to an external compressor.

The z-offset describes the focus setting. If z-offset is set to zero, the laser works "in focus," focusing precisely on the material surface. However, there are also applications where working defocused is desired. When engraving large areas on TroLase, we recommend defocusing 2mm for a consistent engraving result. The following z-offset values are possible: - 5 mm (table moves up, i.e. closer to the material) up to 127 mm (table moves down, further away from the material).