Custom cable materials that withstand extreme temperatures

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Posted On:
December 02, 2020

Excessive heat or frigid cold: discover custom cable materials that withstand extreme temperatures

What are the key cable components and material selections for designing a reliable custom cable used in harsh application environments?

Conductors

At the core of the cable are conductor materials. Selecting the right material makes a big difference on longevity and signal reliability of the cable.

Conductors for High-Temperature Environments

When designing for cables in high temperature environments, consider nicklel-plated copper or alloy conductor materials:

  • Nickel-plated copper
    • Nickle-plated copper is often used in high-temperature applications and can withstand up to 450°C. In addition, the nickel plating offers corrosion and wear resistance.
  • Alloys
    • Alloys are a combination of two or more metals. Silver, nickel, copper, beryllium, cadmium, RoHS-compliant chromium are selected for their overall toughness, break strength, and flex-life. Alloys are another great option for high-temperature applications.

Conductors for Frigid Temperature Environments

If the cable is being designed for frigid temperatures, you will want to keep flexibility in mind. A solid conductor will be more rigid and easier to break when put under stress.

If flexibility is important for your application, select a conductor with a high strand count. As a general rule, the higher the strand count, the more flexible the conductor will be.

Tubing

Tubing is a component with a variety of functions inside of a custom cable. For example, a tube could be used to dissipate heat or to vent pressure or steam. The tube could even be used to carry warm water in order to help protect the cable from getting too cold and failing.

Tubing for High-Temperature Applications

Depending on the specific high-temp application, your cable design engineer will want to ensure that the tube wall thickness and material is suitable for the high-heat exposure and will not break down and potentially expose the conductors.

Tubing for Cold Applications

Tubing may be used inside a cable to vacuum liquids or supply air or other gases. If exposed to a cold environments, a tube material and construction will be selected to ensure the tube will not kink or collapse in the cold environment. Durometer or shore hardness of the material is an important factor. A low durometer may be more flexible, yet some materials can become more brittle and prone to cracking and breaking in cold temperatures. A Northwire Cable Design Engineer will help you make the right choice for your tubing material.

Insulation and Jacketing

When choosing conductor insulation and cable jacket materials for extreme temperature environments, fluoropolymers offer many benefits for both extreme heat and frigid cold. Keep durometer or shore hardness in mind when selecting your conductor insulation and cable jacketing material.

While fluoropolymers perform well in cold temperatures, they become more rigid. A lower durometer material will offer more flexibility but will be more prone to cracking.

Compare the features and benefits of common fluoropolymer materials:

PTFE

  • The most fluorinated of all fluoropolymers, PTFE offers superior performance in extreme temperatures and is resistant to chemicals, oils, solvents, cut, crush, and abrasion
  • The main downside to PTFE has been its ram extrusion with length restrictions based on how much resin can fit into the chamber; Northwire has resolved this downside with an extrudable PTFE that offers a more consistent wall thickness and no length restrictions!

PFA

  • PFA is the closest to PTFE in terms of superior performance characteristics
  • One trade-off for the high-performance characteristics is the price

FEP

  • The first melt processable fluoropolymer to be released
  • FEP does not have the chemical resistance featured by PTFE and PFA
  • Is a cost-effective alternative to PFA when chemical resistance is not imperative

ETFE

  • Features improved cold flow resistance, higher tensile strengths, and increased abrasion resistance
  • Maintains high temperature performance
  • Very good electrical properties
  • Chemical inertness

Other materials such as Santoprene, TPEs, or Northwire BioCompatic Silicone Alternative perform well in extreme temperatures. Northwire cable design experts can assist you with material selection specific to your end application.

As we all know, harsh environments can put added stress on devices and the cable connectivity solution. Below are some additional factors to think about when designing for extreme temperatures, which will impact design choices.

Flexibility

  • Will the cable be used in a static application or will it be moving? Cold temperatures can decrease the flexibility of a cable and make it very brittle. If flexibility is important, consider a TPE (thermoplastic elastomer) or a TPU (urethane) as both jacket materials are rugged and perform well in low temperatures.
  • If instead, the cable would be in a static environment, a good question to ask is whether the cable will be supported/contained or free to move in the wind? If the cable is able to move, brittle point is important because the jacket could crack if the cable could come into contact with other objects at sub-zero temperatures. If that is a possibility, be sure to check the cold bend radius of the material being selected.

Temperature Variation

  • Will the temperature stay relatively constant or will it fluctuate from cold to warm to hot and back to cold? If so, what is the cycle time of the fluctuation?

Liquid Exposure

  • Another consideration is whether the cable will be exposed to liquid. Especially if the temperature reaches the freezing point! You will also want to keep the termination to the connector in mind. If exposed to liquid, it may be wise to use an over-mold to help protect the connection points while being flexed and to help protect from any liquid it may encounter. A water-tight connector may be needed as well to prevent water ingress.

Connector Choice

  • Will the cable assembly be installed and frequently handled in freezing temperatures? If so, be sure to select a connector that features a high mating cycle count, so that the connector housing or internal pins do not crack and break when being connected and disconnected.

There are a variety of custom cable materials and added cable component options such as tubing to consider when putting a design together. Cable design experts are available to make recommendations for appropriate material selection based off of the needs of your specific application and the environment in which it needs to perform. Whether you have a napkin sketch or fully identified specifications, Northwire’s cable designers are here to help.

 

Contact a Northwire Cable Specialist today!