How to save a bundle: Not just any old cable tie

Where you use it, what you’re fastening, and how the environment comes into play are all keys to selecting the right tie.

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Where you use it, what you’re fastening, and how the environment comes into play are all keys to selecting the right tie.

Cable ties, when invented and introduced by Thomas & Betts in 1958, provided a dependable, quick and easy method of bundling and fastening wire and cable in the aerospace industry. Since then, however, the development of cable ties has been driven by new applications beyond aerospace, as well as demand for better ergonomics, labor and cost savings, and improved performance capabilities. These developments over the last 48 years have created a variety of cable tie choices designed to provide an optimum solution for any bundling application.

Application drives the selection

Your application’s environment, such as whether it is indoors or outdoors, its temperature, and the presence of moisture or chemicals, will determine your choice of cable tie material. Additionally, what the cable tie must bundle will determine its length and the tensile strength required.

Cable ties can be classified as either one-piece or two-piece construction:

  • One-piece cable ties typically have a plastic locking device molded into the head of the tie. The locking device ratchets the notched strap to tighten and lock. This design has a lower cost of manufacturing and is used for general-purpose applications.
  • Two-piece cable ties consist of a stainless-steel locking device embedded into the head of the tie, and a smooth locking strap. This design offers high tensile strength, and resistance to mechanical and environmental stress for applications that demand greater performance than what a general purpose cable tie offers. The smooth, infinitely adjustable strap also allows for the exact bundled tightness. The head of the two-piece cable tie engages the strap when installed, and permanently locks in place. In addition, the two-piece design has a lower profile and smoother cross-section, and is more resistant to brittleness and breakage in harsh environments because the uniform cross-section distributes stress across the strap more evenly than with one-piece cable ties. It is particularly appropriate for harsh conditions, such as ultraviolet exposure, extreme temperature, and exposure to moisture or chemicals, as well as for applications where retrofitting is not an option.

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These double-loop cable ties from Thomas & Betts are designed to enable parallel routing of two bundles of cable with a single cable tie. The tail loops twice through the head of the tie in separate locking pawls.
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In addition to the choice between one- and two-piece construction, your cable tie selection criteria must include the most appropriate material for the application. Material selection will depend upon whether the application occurs indoors or outdoors; the environment’s temperature range; the presence of moisture, chemicals and radiation; flammability issues; and cost.

Materials include Nylon 6.6, which is the standard polymer version and is available in a weather-resistant material version and designed to withstand ultraviolet exposure. It is also available in flame-retardant and heat-stabilized versions. Thomas & Betts, for example, uses heat-stabilized nylon for its Ty-Rap Extra-High Temperature Cable Ties, which were designed for extended use in extremely high-temperature environments, such as metal processing and paper mills, as well as for bundling cable for lighting.

Cable ties made of heat-stabilized nylon offer resistance to temperatures up to 300° F comparable to metallic fastening devices, but are easier to install and less costly.

Battling the elements

Other cable tie materials to consider are:

  • Nylon 12, which is also ultraviolet- and weather-resistant, especially in low-temperature applications.
  • Fluoropolymers, which include ethylene tetrafluoroethylene (ETFE, trademarked as Tefzel by E.I. DuPont deNumours and Company), for ultraviolet and radiation resistance, and ethylene chlorotrifluoroethylene (ECTFE, trademarked as Halar by Solvey Solexius), for applications that require flame resistance and low-smoke generation.
  • Acetal, which is ultraviolet-resistant and performs well in low-temperature applications.
  • Polypropylene, which is resistant to weather and chemical exposure.
  • Hook-and-loop material (Velcro), which offers reusability.
  • Stainless steel, which is highly resistant to all conditions and offers the greatest tensile strength, but is costly and rougher on bundled items.

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Designed to prevent snagging when cable is trimmed and the harness is pulled through a bulkhead, the tamper-proof Push-Mount tie from Device Technologies helps prevent damage from sharp edges and can snap quickly into place.
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Each of these materials offers its own combination of resistance to the elements, temperature range and cost. Nylon and polypropylene cable ties are low to moderately priced, while specialty cable ties made from fluoropolymers, acetal or stainless steel are more expensive. Thomas & Betts’ recently introduced Ty-Rap Detectable Cable Tie (shown below), available in either Nylon 6.6 or polypropylene, features metallic additives that enable the tie to be identified by metal detectors that screen for contaminants in processing environments. Both materials also are dense enough to be detected by X-ray equipment. The polypropylene version is also buoyant for easy detection in liquid processing applications.

Sizing up the situation

In addition to material, other considerations for selecting a cable tie should include:

  • Required tie length, which can be determined by the diameter of the bundle. (Common cable ties vary in length from 3.6 to 48 inches.)
  • Required tensile strength, which is determined by the weight of the bundle’s load.
  • Cable tie color, for which an assortment is available to match equipment or to function as color-coding in identifying circuits.
  • The application for which the cable tie will be used. The choice of cable tie design is determined by the application’s performance requirements, and if the installation is permanent or temporary.

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The Detectable Cable Tie, from Thomas & Betts, is made with metallic additives that enables it to be identified by metal detectors that screen for contaminants in processing environments.
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Standard cable ties have developed beyond their original application in the aerospace industry to bundle and fasten wire and cable for any electrical or wire harnessing application. The expansion of cable tie applications has led to variations of the standard design. Examples include screw-mount cable ties for surface mounting applications; push-mount cable ties for pre-drilled hole mounting, such as copier machine and appliance assembly; messenger hanger and lashing cable ties for utility and railway applications; low-profile head cable ties for electronic assembly; cable tie strap and separate locking head for telecommunications cable, pipelines, large duct work and packaging; and restricted bundle cable ties for luggage and badges.

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Unirap ties from FCI feature compact heads and pre-bent tips designed to simplify cable bundling. These specialty ties, built for such applications as aerial support, mounting bases, and military, are resistant to a variety of environmental fluids and acids, as well as flame.
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Another example of the range of designs is the double-loop cable tie, which enables parallel routing of two bundles of cable with a single cable tie. The tail loops twice through the head of the tie in separate locking pawls.

Other styles include nail-on cable ties for landscaping and residential uses, which enable bundles to be secured to wood surfaces; plug-mount cable ties for masonry construction, which lets bundles be secured to masonry surfaces with a plug on the cable tie’s head that fits into drilled holes; and button-head cable ties for automotive chassis and electrical equipment applications, which resemble rivets when installed. Reusable cable ties for temporary bundling are also available.

Among developments in cable tie design is the need for specific application identification. Bi-colored, striped cable ties, for example, are often used for telecommunications and data-communications cabling. In addition, write-on identification plates can be secured to bundles with cable ties, snap-on marker tags can fasten to the head of a conventional cable tie, and cable ties molded with the identification plate on or below the head are also available. Tags can be labeled with permanent-ink markers or can be heat stamped.

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With ties made for miniature to heavy cross-section applications (18 to 175 pounds), Panduit's Super-Grip line feature a high-grip strength designed to prevent lateral tie movement on the bundle, and strap flexibility to conform to irregular bundle shapes.
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Before choosing a particular cable tie, make sure you test it to verify your selection’s performance and suitability for each application.

Don’t forget the tools

In addition to selecting the best cable tie for the application, using a cable tie installation tool eliminates the risk of applying incorrect tension when ties are fastened by hand.

A suitable cable tie installation tool includes a tension adjustment knob that ensures the correct tension level for each application. Excessive tightening of a one-piece cable tie, for example, will cause the tie’s teeth to dig into the wire or cord insulation.

Other tools include cable tie dispensers, which clip onto a belt or tool pouch, freeing the installer’s hands and reducing the number of cable ties that are dropped or lost.

Finding one that fits

Developments in cable tie design and the use of different materials have provided a wide range of choices in determining the correct cable tie for a particular application. The demands made by your application’s load and function will determine the cable tie’s type, design, tensile strength, length and sometimes its color. In addition, the application’s environment, including temperature, ultraviolet exposure and the presence of corrosive elements, will determine the best material to select.

Finally, the cost of the cable tie should be weighed against how critical the application’s demands really are. A lower cost cable tie may not function as well for demanding applications where tensile strength or resistance to elements is important. But the range of choices available ensures that there is an effective cable tie solution for any application.

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ROB DeWEEZ is product manager for Thomas & Betts Industrial Products Group (www.tnb.com), Memphis, TN.

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