Heat shrink tubing is widely used for insulation, cable protection, and strain relief. However, under certain conditions, it may become brittle, split, or crack over time.

1. Overheating During Installation

Excessive heat can damage the tubing material and reduce its flexibility and strength.

Common signs include:

• ● Surface cracking
• ● Burn marks
• ● Blistering
• ● Brittleness

To prevent overheating:

• ● Keep the heat source moving
• ● Avoid heating one area too long
• ● Apply heat gradually

Heat guns usually provide more controlled heating than open flames.

2. Incorrect Tubing Size

Using tubing that is too small may overstress the material during shrinking and cause splitting.

If the shrink ratio is incorrect, the tubing may either crack or fail to seal tightly.

3. UV Exposure and Aging

Sunlight, moisture, and outdoor weather can gradually degrade some heat shrink materials.

Over time, the tubing may:

• ● Lose flexibility
• ● Become brittle
• ● Develop cracks

UV-resistant tubing is commonly recommended for outdoor use.

4. Mechanical Damage

Sharp cable edges, vibration, repeated bending, or pulling stress can weaken the tubing and eventually lead to cracking.

Conclusion

Heat shrink tubing commonly cracks because of:

• ● Overheating
• ● Incorrect sizing
• ● UV exposure and aging
• ● Mechanical stress
• ● Poor material quality

Choosing the correct material and applying heat properly can greatly improve long-term durability and performance.