Laser Marking of Coated Materials: How to Avoid Burning

The coating materials used in the process tend to burn easily when subjected to the heat of the laser beam, which can adversely affect the quality of the marking.From three angles--parameter settings, material characteristics, and process optimization--he shared how to avoid scorching by adjusting key parameters such as laser power, frequency, and speed, and by combining these with techniques for processing the surface of the material.

Why does the coating material easily burn?

The material of the coating is different from that of normal metals. The surface coating (such as a coating from electroplating or spraying) is uneven in thickness and chemical composition, and is also a poorer heat conductor.If the energy is too high or the laser stays in the same place for too long, the coating could carbonize or fall off, leaving behind a burned black mark.Especially with common materials like gold plating and black oxidation, a slight mistake can result in a "crash.

The key method for solving the problem of burnt food.

First, you have to get to know the nature of your materials.

Don't rush to print! First make sure you know the type and thickness of the coating.For instance, the heat-resistance of nickel plating and anodization are very different.You can try different parameters on small samples, and observe the point where the chips are burned.Remember to look at the details under the microscope. Sometimes it may look fine to the naked eye, but when you zoom in, the edges may be blurry.

Power and speed must be in perfect balance.

Turning down the power is not the solution! Many people, to prevent burning, simply turn the power down to the lowest setting. The result is that the markings are unclear.The correct approach is to use a medium power flash with a fast shutter speed to ensure good color reproduction.For example, they would start by testing at 50 % power and 800mm / s speed, then fine-tune until they found the right balance.

Use auxiliary gases and marking mode.

Adding an air nozzle to the laser head to use compressed air to cool the area being engraved prevents heat buildup.If it is a delicate design, try the "filling interval" mode, which allows the laser to work in a dot matrix rather than drawing a continuous line, giving the material time to cool.

The details of daily operation.

Calibrating the light path and focal distance on a regular basis.

If the laser head is off-center or the focal length is incorrect, the energy distribution will be uneven, and the disc will be burned in spots.We recommend that you check the quality of the beam spot with calibration paper once a week, and that you test the focal length before marking--especially when changing to a workpiece of a different thickness.

The pre-treatment cannot be done half-heartedly.

If the metal surface is oily or oxidized, first wipe it clean with alcohol, and if necessary, treat it with sandblasting.The clean surface reduces laser reflection, lowers the energy required, and cuts the probability of charring in half!

The temperature and humidity must also be controlled.

High temperatures or humidity can affect the speed of heat dissipation from the material and the stability of the laser.Keeping the temperature at about 25 degrees and the humidity under 60 percent will greatly improve the tolerance of the parameters.