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How to Use Heat Shrink Tubing: Shrink Temperature, Size Selection, and Heat Gun Tips
How To Guide · Heat Shrink Tube · Usage
Correct Use of Heat Shrink Tubing
Correct Use of Heat Shrink Tubing
Shrinkage Temperature, Size Selection, and Heating Tips
We explain the relationship between shrinkage temperature and shrinkage rate with our own measurement data graphs.
Heat shrink tubing is a simple product that "shrinks when heat is applied," but if you get the heating temperature, size selection, or heating method wrong, it may not shrink properly or the insulation may melt. This page explains practical tips for immediate use on-site, including our own measurement data.
Relationship between Shrinkage Temperature and Shrinkage Rate [Our Measurement Graph]
The graph below shows actual measurement data of heating temperature and shrinkage rate for our polyolefin heat shrink tubing (THT series). We have measured the detailed behavior not published in catalogs in-house.
| Temperature | Shrinkage Rate (目安) | Condition/Comments |
|---|---|---|
| 〜70℃ | approx. 5% | Almost no change. Boundary for shrinkage to begin. |
| 80℃ | approx. 20% | Shrinkage begins. Near the limit for a hair dryer (low setting). |
| 90℃ | approx. 50% | Rapid shrinkage. A few seconds with a heat gun. |
| 95〜100℃ | approx. 58〜60% | Reaches maximum shrinkage rate. No further change with more heating. |
| 120℃ and above | approx. 60% (no change) | Overheating. Risk of discoloration or melting of the covering. |
Key point: The shrinkage rate changes rapidly within the 10℃ range of 90℃ to 100℃. Moving the heat gun to pass through this temperature range quickly is the key to a clean shrinkage finish.
Actual Shrinkage (Video)
How to Choose the Size | Inner Diameter, Recovered Inner Diameter, Wall Thickness
Selecting the size of heat shrink tubing fundamentally involves checking three numbers.
| Item to check | Meaning | Selection guideline |
|---|---|---|
| Pre-shrink inner diameter | Inner diameter before the tube is applied | Choose a size 20-30% larger than the outer diameter of the object |
| Recovered inner diameter | Inner diameter after maximum shrinkage | Must be smaller than the outer diameter of the object (to ensure snug fit) |
| Wall thickness | Thickness of the wall after shrinkage | For insulation/waterproofing, 0.8mm or more is a guide |
A common mistake is that the "tube won't fit" because the pre-shrink inner diameter is too small. Please reselect a size of object diameter x 1.2 to 1.3. If it is "loose or gapped after shrinking," consider changing to a product with a larger shrink ratio (such as 3:1).
Heating Method | How to Use a Heat Gun and Hair Dryer
RECOMMENDED · STANDARD HEATING METHOD
When using a heat gun
-
1
Set temperature: 200〜300℃ (adjust distance so tube surface reaches 90〜100℃)
-
2
Distance: 3〜5cm away from the tube. Too close will burn one spot.
-
3
Movement: Move evenly from end to end. For finishing, rotate the tube to heat all sides for a better fit.
SUPPLEMENTARY · ALTERNATIVE HEATING METHOD
When using a hair dryer
The maximum temperature of a household hair dryer is about 80°C, so it can only be used for thin-walled, small-diameter tubes. For large-diameter and waterproof types, a heat gun is necessary as sufficient shrinkage cannot be achieved. In some cases, it may be compatible with tubes that have a shrinkage start temperature below 70°C.
Common Mistakes and Solutions
| Mistake | Cause | Solution |
|---|---|---|
| Uneven shrinkage / wrinkles remain | Localized heating | Heat slowly and evenly from end to end |
| Tube burnt / melted | Overheating / too close distance | Move heat gun away from tube / increase moving speed |
| Turned cloudy white after shrinking | Overheating PVC tube | Switch to polyolefin or reduce heating temperature |
| Edges curling up | Overheating edges only | Heat from the center towards the ends |
| Cannot pass through harness | Connector snags | Use post-installation compatible tubes |
Recommended Products by Application
| Application / Condition | Recommended Product |
|---|---|
| General insulation/protection (standard product) | THT (Polyolefin, 60% shrink rate, starts shrinking from 70℃) |
| Flame retardancy required (UL standard) | List of UL standard compliant heat shrink tubing |
| Waterproofing / moisture proofing required | List of waterproof heat shrink tubing (with adhesive) |
| Large diameter of 50φ or more | List of large diameter heat shrink tubing |
| Want to install tube later | List of post-installation compatible tubes |
| Heat resistance of 125℃ or higher required | List of heat-resistant shrink tubing |
Summary · Key Usage Points
Shrinkage Temperature
90〜100℃ is the inflection point
Shrinkage begins at 70℃. Reaches maximum (approx. 60%) quickly between 90〜100℃.
Size Selection
Object diameter × 1.2〜1.3
Check pre-shrink inner diameter, recovered inner diameter, and wall thickness before selecting.
Heating Method
Evenly from end to end
Heat gun 200〜300℃, 3〜5cm distance, do not apply heat to one spot continuously.
For more detailed selection advice, please contact us. We will recommend the optimal product based on your application, environment, and size requirements.
Consultation for Size Selection and Samples Here
We will propose the optimal product if you inform us of your application, environment, and size.
