Emergency Repair of Microcracks in Glass After Laser Marking

The guide offers a quick solution to the problem of microcracks appearing in glass after laser marking, and covers crack detection, choice of repair materials, repair procedures, and preventive techniques, to help reduce waste and losses.

Why should laser marking cause glass to crack?

Although laser marking machines are precise, glass has poor thermal conductivity, so local heating can cause stress to build up.In particular, when the power setting is too high, the focus is not precise, or the glass itself has impurities, it is like using a magnifying glass to burn paper. If you are not careful, you may leave behind tiny cracks that are difficult to see with the naked eye.If these cracks are left unattended, they may suddenly widen under the influence of external forces or temperature differences.

Three steps to quick detection.

The side-view method.

Turn off the main light in the room, and shine a flashlight at the glass at a 45 ° angle.The microcracks reflect a fine web of light, and can be seen 10 times more clearly than with the naked eye.

Alcohol development.

A cotton swab dipped in alcohol is then used to wipe the area. The alcohol seeps into the cracks and leaves a dark stain. This method is especially good for detecting cracks less than 0.1 millimeter in width.

Professional equipment.

If conditions permit, a 20x or greater industrial magnifying glass or fiber-optic microscope can be used to accurately judge the depth and direction of the crack.

These are all methods that have been personally tested.

Nanometer glass filler

1. First use a compressed air gun to clean the debris.

2. Use a syringe to fill the crack with filler, injecting it slowly.

3. UV light hardens the adhesive in 30 seconds.

We just tried this method in the workshop last week, and the repaired phone passed a 1-meter drop test.

The final step in the process is tempering.

Control the oven temperature at 280 ℃ ± 5 ℃, and slowly increase the temperature and hold for 15 minutes.Note: If the temperature rises over 300 ℃, the crack may expand. It is recommended that you use an infrared thermometer to monitor the temperature continuously.

Daily prevention tips.

1. Before engraving, wipe the glass surface twice with alcohol. Don't underestimate the effects of fingerprints and grease. These impurities can cause the laser power to be unevenly distributed.

2. Power parameters are tested at 60 % of the rated power, then gradually increased.

3. The lens must be cleaned with a brush after every 20 wafers are processed.

For particularly complicated cracks, it is best to contact the laser manufacturer to adjust the laser parameters.Remember, the earlier the treatment, the greater the chances for success.