Laser Marking Ceramics: Temperature Control Is the Key

The cracking of ceramics after the laser has been applied is most often related to improper temperature control.It helps you set parameters, reducing processing losses and improving yield.

Why does laser marking cause ceramics to crack?

Ceramics are brittle, have poor thermal conductivity, and have a low coefficient of thermal expansion.The laser heats the material to a high temperature, and if the heat is not distributed evenly or the cooling process isn ’ t even, the stress within the material can be released suddenly, causing cracks. This is especially true of hard materials such as aluminum oxide ceramics.

These are the three key points in temperature control.

The higher the power, the better?

Many people think that "high power = high efficiency," but ceramics are extremely sensitive to high temperatures.He advises starting with a low power level when testing, for example, using a 20-Watt laser at 30 % power, and gradually adjusting the depth of the mark. This avoids overloading the laser with too much energy all at once.

Don't ignore the pulse frequency.

The frequency of the pulses determines the interval between laser actions.A frequency that is too high will cause the heat to build up and the ceramic will not have enough time to dissipate it. A frequency that is too low will result in an unclear mark.The frequency range is controlled between 20-50kHz, with the exact frequency depending on the thickness of the ceramic.

The cooling speed must be "just right.

After the glaze has been applied, the pottery is allowed to cool naturally.Don't rush to use cold water or a fan to cool it down--sudden changes in temperature will cause the glass to shatter.If conditions allow, the cooling can be assisted with a cooling chamber, with the rate of cooling kept at 5 ° C per minute or less.

Tips for real-world debugging.

1) Try it out with scrap: The composition of ceramic material can vary from batch to batch. It is recommended that five to ten sets of parameters be tested on scrap.

2. Observe color changes: After firing, the surface of a ceramic piece should be a light gray or white. If the surface turns black or yellowish brown, it means that the temperature was too high.

3. Listen for sounds: A slight cracking sound when the laser head moves may be a sign of imminent damage.

If the ceramic is still cracking too much, check to see if the focusing lens is dirty (which would affect the concentration of the laser energy), or consider coating the ceramic with a light-absorbing material to reduce the amount of laser power needed.