More Information About Fluropolymers
Fluoropolymer sleeving and shrinkable tubing is available in a variety of plastic compounds from the basic PVC and polyolefin to the more expensive fluoropolymers compounds, such as PTFE, PFA, and FEP. Each material has its strong point and proper selection of material should not always be made based upon cost. Electrical properties, temperature rating, and chemical compatibility should all be considered when choosing the proper size for your application. You should always try to select a tube that is in the middle of your shrink range. Selecting too high means that you have a lot of stress still built up in the material and selecting too low means that there is a possibility that the product might not shrink enough.
Polytetrafluoroethylene (PTFE) has the highest temperature rating of all heat-shrinkable tubing at a continuous 500°F. The biggest drawback is that PTFE heat shrink tubing products require a minimum temperature of 625°F to begin the shrinking process. This includes the part that is being encapsulated. If the subsurface doesn’t reach 625°F, the PTFE will come in contact with the part but will not shrink completely. Lower-temperature fluoropolymers, such as fluorinated ethylene propylene (FEP), have a little lower temperature rating but shrink at a much lower and more controllable temperature. FEP has a continuous working temperature of 400°F but will start to shrink around 230°F which allows for encapsulation of sensitive glass or plastic parts. Both fluoropolymers are chemically inert and may be used on all sorts of applications, such as corrosive fluid handling, and even medical applications, such as coatings for catheters. PTFE tubing is known for its low coefficient of friction which makes it great for push-pull type applications that dominate the automotive industry.
High-temperature wire splicing applications can benefit from an interesting match of PTFE and FEP tubing which, when combined, create a melt liner or adhesive liner. This liner bonds to bare wires and creates an impenetrable watertight barrier between the elements and the splice.
When selecting a PTFE heat shrink tubing product for your application, there are two other factors to consider: shrink ratio and wall thickness. PTFE tubing can be developed in an extremely high shrink ratio, such as a 4:1, which is perfect for covering oddly shaped parts, or a standard 2:1 shrink ratio. Wall thicknesses are based off of the American Wire Gauge (AWG), and are set at light wall, thin wall, and standard wall.