Dunbar 1635F Heat Shrink Tubing
The Dunbar 1635F is a flexible, flame-retardant, 2:1 heat shrink tubing made from crosslinked polyolefin. It is one of the most widely specified products in the heat shrink category, used across military, aerospace, and commercial applications for electrical insulation, wire strain relief, and component protection.
At Electro Insulation, we supply Dunbar 1635F heat shrink tubing and provide value-added services including cut-to-length tubing, hot stamp and thermal transfer printing, kitting, and custom packaging. Available in 12 standard colors and sizes ranging from 3/64" to 5", this tubing is built to meet demanding project requirements. Request a quoteor call us at 1(800) 247-2114 to speak with a tubing specialist.
For more detailed specifications, view the Dunbar 1635F Technical Data Sheet.
Key Features of Dunbar 1635F
The Dunbar 1635F delivers a 2:1 shrink ratio, meaning the tubing reduces to 50% of its original diameter when heat is applied. Longitudinal shrinkage is held to 5% or less, which helps maintain positioning on the component during recovery.
This tubing carries a UL VW-1 flame rating (CSA OFT) and is rated for 600V at 125°C under UL 224 (File Number: E319303). Clear tubing is the exception and does not carry the VW-1 rating. The Dunbar 1635F also provides strong resistance to abrasion, chemicals, and oils, making it a reliable choice in environments where exposure to these elements is a concern.
All Dunbar 1635F tubing is both RoHS and REACH compliant. It is also printable at low temperatures via thermal transfer or hot stamp methods, which supports wire identification and traceability requirements onmil-spec projects.
Ideal Applications for Dunbar 1635F
The Dunbar 1635F is designed for a wide range of uses. Its primary applications include insulation for electrical and electronic devices, wire strain relief, and protective covering for components such as resistors and capacitors.
Because this tubing meets SAE AS23053/5 Class 1 and Class 3 requirements (formerly AMS-DTL-23053/5), it is QPL (Qualified Products List) approved for military and aerospace programs. Class 2 (clear) tubing is also available for applications where visual inspection of underlying components is necessary.
Beyond military use, the Dunbar 1635F serves commercial and industrial projects that require wire bundling, color coding, solder insulation, and lightweight harnessing. Its continuous operating temperature range of -55°C to +135°C makes it suitable for both extreme cold environments and high-heat enclosures. Available in 12 standard colors (black, clear, red, white, blue, yellow, brown, gray, orange, green, violet, and yellow/green), it supports detailed wire identification and color coding across complex harness builds.
Technical Specifications
The following specifications are verified from the Dunbar 1635F product datasheet (Rev. March 2024).
Physical Properties
Unaged tensile strength (ASTM D638): Min. 1,500 psi. Elongation: Min. 200%. Aged elongation (ASTM D638): Min. 100%. Fluid resistance tensile strength (24°C/24 hrs, 6 fluids): Min. 1,000 psi. Fluid resistance dielectric strength: Min. 400 Volts/mil. Heat shock (250°C/4 hrs): No cracks, flowing, or dripping. Low temperature flexibility (-55°C/4 hrs): No cracking. Secant modulus (ASTM D882): Max. 25,000 psi. Specific gravity (ASTM D792): Max. 1.35 (Max. 1.00 for clear).
Electrical Properties
Dielectric strength (ASTM D2671): Min. 500 Volts/mil. Volume resistivity (ASTM D876): Min. 10¹⁴ Ω·cm.
Chemical Properties
Copper corrosion (175°C/16 hrs): No corrosion. Fungus resistance (ASTM G21): No growth. Water absorption (ASTM D570): Max. 0.5%.
Operating Parameters
Minimum shrink temperature: 90°C. Continuous operating temperature: -55°C to +135°C. Shrink ratio: 2:1 (radial), 5% or less (axial). Concentricity (ASTM D2671): Min. 70%.
Sizes range from 3/64" (1.2mm expanded ID) through 5" (127mm expanded ID), with metric sizes available by special order. The Declared Dimension Life (DDL) is 10 years.
FAQ
What products does the Dunbar 1635F cross-reference to?
The Dunbar 1635F is a direct cross to several industry-standard part numbers, including the Sumitomo B2, Raychem RNF-100, Alpha FIT-221, 3M FP301, and Canusa CPX-100. If you are currently specifying any of these products, the Dunbar 1635F meets the same SAE AS23053/5 requirements and can serve as a qualified replacement.
What is the difference between Class 1, Class 2, and Class 3 on the Dunbar 1635F?
Class 1 is flame resistant and covers the standard colored tubing options. Class 2 is the clear (non-flame-resistant) version, which does not carry the UL VW-1 rating. Class 3 is a highly flame-resistant grade. All three classes fall under the SAE AS23053/5 specification, and the Dunbar 1635F is QPL approved for Classes 1, 2, and 3.
What heat source is needed to shrink the Dunbar 1635F?
The minimum shrink temperature for Dunbar 1635F is 90°C. A standard hot air gun is the most common method, though an oven can also be used for batch processing. Ensure the heat source can reach and maintain at least 90°C for full recovery to the 2:1 ratio.
Does the Dunbar 1635F have a shelf life?
Yes. The Dunbar 1635F carries a Declared Dimension Life (DDL) of 10 years. This means the tubing will maintain its specified expanded dimensions for up to 10 years from the date of manufacture when stored under proper conditions.