Heat-shrink tubing, commonly known as heat-shrink, is a polymer based tubing that is often used to seal, insulate, and protect wires and cables. As denoted by the name, heat-shrink tubing is designed to contract when an external heating source is applied to it, thus adhering to the cables and wires to which it is wrapped around. For use cases involving harsh environments and extreme conditions, fluoropolymers based heat shrink tubing is the way to go. Fluoron is uniquely equipped to custom manufacture fluoropolymer based heat shrink tubing, and offers services to do this at the large diameter scale unlike conventional offerings.
A Key Quality of Fluropolymers
A key advantage of fluoropolymer heat shrink tubing is its ability to withstand high temperatures. PTFE, for example, can operate at temperatures up to 260°C (500°F), while FEP and PFA can operate at temperatures up to 200°C (392°F) and 260°C (500°F) respectively. On the low temperature end of the spectrum, PTFE, FEP and PFA are able to operate at the cryogenic level – meaning that performance is also maintained in cold corrosive environments, like ones that involve sulfuric acid. This makes them suitable for use in applications where traditional heat shrink tubing would not be able to withstand the heat generated, such as in high-temperature industrial or commercial aerospace applications.
Though it can be made from a variety of materials, Polytetrafluoroethylene. (PTFE), Fluorinated ethylene propylene (FEP), and Perfluoralkoxy (PFA) are prime candidates for heat shrink tubing. The use of fluoropolymer heat shrink tubing provides incentives for cost saving in the aerospace industry as well. Traditionally, exotic metals with high melting points and anti-corrosive properties have been used in aerospace applications. However, their high cost to acquire, relative difficulty to form into custom shape, weight properties and high cost have proved detrimental to legacy aerospace systems. These parts are usually made from titanium and nickel alloys, and included in aircraft components such as engine enclosures, fuel enclosures and hydraulic tubing. In the same vein, fluoropolymer based tubing provides the same, if not superior features, higher availability and lower cost – especially for scenarios involving large diameters.
Fluoropolymer Heat Shrink Tubing in Aerospace Applications
Applications for fluoropolymer heat-shrink tubing in the aerospace industry are extremely versatile. Avionic systems within the aerospace industry are often exposed to a spread of harsh conditions. These conditions can range from: extreme temperature, exposure to moisture, exposure to dust, chemical contaminants, vibrational resonance, and mechanical stress and strain. However, fluoropolymer heat shrink tubing provides protection from all of these conditions when properly secured and adhered to the respective system components that will be deployed under the aforementioned conditions. Due to its inherent properties of being inert, lightweight and durable, fluoropolymer heat shrink can be deployed in chemically caustic environments. Unlike traditional heat shrink, it is highly resistant to chemical degradation – making it the prime candidate for high temperature fuel lines, engines, and electrical power systems, and electronic subsystems on an aircraft. The resistance to chemical degradation also bodes well for keeping the previously mentioned materials safe from contamination. This is especially important for fuel systems, whose purity must meet a quality standard in parts-per-million (ppm) to assure a smoothly running system. Due to its lightweight properties, fluoropolymer tubing can also be custom shaped depending on the use case. Custom shaping is achieved by thermoforming the fluoropolymer, to manipulate its physical shape while persevering its physical and chemical properties.For example, at the large diameter, Fluoron has the ability to provide custom tubing for nose cones on aircrafts as opposed to the conventional tubing used. As such, this minimizes drag and other aerodynamic forces experienced by the aircraft while maximizing in-flight modulation.
Anti-Static Properties of PTFE Based tubing
Another useful property provided specifically by Fluoron’s PTFE based heat shrink tubing is its anti-static benefits. Static electricity has been recognized as a workplace hazard that introduces another layer of complexity to safety critical systems, like ones in aerospace. In a heterogeneous environment, where components are in close proximity, rubbing together, or enclosed in the same constrained space, many problems can arise. At a small scale, static can fry electronic systems – causing immediate or delayed major failure of circuit level components. At a large scale, introduction of static to a system can increase chances of electrical fires and even explosions. Traditionally, fluoropolymers are insulators, and therefore do not allow free electrons to easily move through them. This buildup of non-moving electrons is what results in static electricity being introduced to a system. However, with a custom PTFE and graphite process used by Fluoron engineers, the possibility of introducing static to a system is eliminated. The process of adding graphite employs the use of graphite fillers in the tubing, which adds a layer of conduction below the surface thus allowing the electrons to move freely and avoid static buildup. The addition of graphite also follows a convention called the percolation threshold. In the percolation threshold, for a certain concentration of graphite introduced to the fluoropolymer there is a linear increase in conductivity of the fluoropolymer material. Therefore, after a certain point, adding extra graphite does not increase electric conductivity and anti-static benefits.
Flouron’s Large Diameter Heat Shrink Tubing Product: Fluorostat
Within the Fluoron product portfolio, Fluorostat provides the ability to do large diameter heat shrink tubing for the aerospace applications noted above. Fluorostat is carbon filled using the custom process provided by Fluoron engineers and utilizes a proprietary seaming technology in its manufacturing. As such, this enables the needed anti-static properties to protect systems from component level electrical failure or subsystem level flammable failure. It is currently offered at 0.060’’ and 0.0090’ thickness – either of which can be thermoformed into a custom shape, used as a liner, or used for tubing. As such, Fluoron is the only company on the market that is able to offer this carbon filled PTFE material in the form of a heat shrinkable jacket.
