Heat Shrink Tubing Review and Application

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Heat Shrink Tubing Review

Heat shrink tubing is a material that contracts or shrinks diametrically when a specified heat source is applied. Heat shrink tube shrinkage is material or product dependant. Shrinkage rates vary from 5 percent of nominal diameter up to 50 percent or more. Heat shrink tubing is used to provide a protective covering for wire cable ends, packaging materials, bundling and organizing wire cable, sealing and protecting solder ends, and more. Heat shrink tubing can provide protection from temperature variations, moisture, corrosion, shock, and other harmful environmental challenges. Heat shrink tubing is available in many different diameters, colors, materials, dielectrics, etc.

Heat shrink tubing is manufactured in a multitude of varieties and chemical makeups with the exact composition of each type being dependent on the intended application. From near microscopically-thin-wall tubing to rigid, heavy-wall tubing, each type has precise design and chemical additives that make it suitable for meeting any of a wide variety of environmental demands. Heat shrink tubing is rated by its expansion ratio, a comparison of the differences in expansion and recovery rate.

Application: Heat shrink tubing should be sized based on the actual diameter of the cable or feature to be covered. Normally the shrink tubing diameter is large enough to fit over all associated coverings and obstructions. The shrink tubing specified minimum shrunk size should be smaller than your diametric application. Adequate shrink tubing overlap should be included in the finished length of the application. Be aware that the shrink tubing will shrink longitudinally as well.

Shrink Tube Materials

• PTFE (fluoropolymer) tubes have a wide operating temperature range (-55 to 175 °C), a low coefficient of friction, and high resistance to chemicals and punctures.
• Viton, another fluoropolymer with high chemical resistance, is widely used in hydraulic equipment. It is highly flexible, with a very wide operating temperature range of -55 to 220 °C, making it suitable for protecting sensitive devices against heat.
• Polyvinylidene fluoride (PVDF) tubes are intended for high temperature applications.
• Fluorinated ethylene propylene (FEP) is a lower-cost alternative to PTFE. It is a versatile electrical insulator and is inert to most chemicals and solvents. Additionally, it is highly resistant to extreme heat, cold, and Ultraviolet radiation, making it an excellent material for heat-shrink tubing applications.
• Elastomeric tubes maintain high flexibility even at low temperatures and meet stringent international specifications. Their operating temperature range is -75 to 150°C. The material is resistant to many chemicals (including diesel and petrol) and has good resistance to abrasion, even in severe environmental conditions. A common shrink ratio is 2:1.
  Silicone rubber offers excellent resistance to scrape abrasion and high flexibility. Its operating temperature range is -50 to 200°C
• Polyolefin tubes, the most common kind, have maximum continuous-use temperatures from -55 to 135 °C, and are used by the military, aerospace and railway industries. They are flexible and fast-shrinking, and manufactured in a wide range of colors (including clear), which can be used for color-coding wires. With the exception of black, they tend to have lower resistance to ultraviolet light; accordingly, only black is recommended for outdoor applications. A common shrink ratio is 2:1, but high-grade polyolefin heat shrink is also available with a 3:1 ratio.

Raychem pioneered EVA:The EVA based formulation with multiple chemicals added to perfect its usage for Electrical applications, has undergone Accelerated Ageing tests. The EVA formulations provide excellent UV and weather resistance to prevent dry banding and erosion.The formulations are Non Halogen and zero Halogen as well.

• PVC tubes are available in several colors and can be used outdoors.

Other special materials exist, offering qualities such as resistance to diesel and aviation fuels, and there is also woven fabric, providing increased abrasion resistance in harsh environments.