What are the reasons for automatic glass cracking?
2 Answers
Glass may crack automatically due to the following reasons: 1. External force impact, such as being hit by flying stones or debris; 2. Excessive temperature difference between the interior and exterior of the vehicle, caused by extreme air conditioning cooling under intense sunlight, leading to thermal expansion, contraction, and uneven cooling; 3. Presence of bubbles, cracks, or impurities in the glass during production; 4. Insufficient installation clearance or direct contact between the glass and the frame, creating pressure on the edges or corners; 5. Glass processing factors, such as drilled holes or cut corners, which make the glass more prone to cracking; 6. Severe weather conditions like strong typhoons, causing failure in wind pressure resistance design. Automotive glass is manufactured by heating the glass to near its softening point in a furnace, then rapidly transferring it to cooling zones with varying intensities for uneven cooling.
I've been repairing cars for many years, and there are quite a few common reasons for car windshields cracking on their own. Temperature changes are one of the main culprits—for example, after a car is left in the scorching summer sun, the internal temperature skyrockets, and suddenly turning on the air conditioning causes rapid cooling. The uneven expansion and contraction between the inner and outer layers of the glass can lead to stress buildup, resulting in cracks. Or in winter, heating the car too quickly after it's frozen can also cause cracks due to extreme temperature differences. Another common cause is small stones or debris hitting the windshield, which might go unnoticed at the time but accumulate into micro-damages over time. Manufacturing flaws like bubbles or impurities shouldn’t be overlooked either, as these hidden defects weaken the glass. Improper alignment during installation or loose glass mounts can add extra stress. Long-term driving on bumpy roads accelerates aging due to vibration fatigue. If you notice a crack, don’t delay—get it checked by a professional shop immediately and replace the windshield to avoid safety hazards.
