There will always be a need to install constraining (safety) devices to threaded fasteners in applications where vibration, kinetic energy, or the need for high reliability is present. Their purpose is to restrict (to a minimum) the unintentional rotation of the fastener. The traditional method (devised in the early 1900’s) is through the use of Hand Twisted Safety Wire (often called Lock wire). The only changes which have occurred since the early uses of Safety Wire are the tremendous costs in the installation of this material, and the levels of sophistication in the systems on which Safety
Wire is being installed. It is used in Jet Engine systems, Airframes, Electronics, Space Vehicles,
Safe-T-Cable™ was invented to address these problems in modern Airframe and Engine Systems. The Safe-T-Cable™ Kits are consistent in their construction/ application, and the user-friendly tooling guarantees a secure and reliable installation each time it is used. Operator training is simple, Inspection is objective, and rework is virtually eliminated. This results in fewer demands on the Operators, Inspectors, and Maintenance personnel.
Safe-T-Cable™ is constructed of high tensile strength, stranded cable. It is more flexible than its Safety Wire counterpart, although the working diameters are equivalent. This provides a stronger assembly which has greater strength and lighter weight. The cable ends are electrically fused to form an easy threading end.
The cable is pre-cut to various lengths, and is supplied with a square-formed end cap attached to one end. Safe-T-Cable™ is available in four nominal diameters. The .040 inch diameter cable is constructed of 737 stranded ropelay material. Ropelay construction is also used for the 337, .032 inch diameter cable while the .022 inch diameter cable is made of 137 unilay material.
The ferrules are precisely manufactured to a size and hardness which assures their compatibility with the cable and application tooling. They are supplied (50 pieces each) in an easy loading disposable cartridge, which provides orderly containment of individual ferrules, and the easy release of individual ferrules as they are required. This feature minimizes the possibility of Foreign Object Damage (FOD).
The application of Safe-T-Cable™ is consistent from one installation to the next due to the repeatability and dependability of the application tooling and the quality of the materials used in the manufacture of Safe-T-Cable™ Kits. All that is required to assure overall reliability in manufacturing and maintenance use is a periodic test of a few crimped cable assemblies. DMC offers full instructions and the test equipment to perform these simple tests in either remote or test lab locations.
The same high performance alloys used in aerospace fasteners and other components are also used in the construction of Safe-T-Cable™ to provide strength and corrosion resistance that is required for durability and long life. All components (End Fitting, Cable, and user applied Ferrule) are made of the same material. 321 Stainless Steel (AS3510) is the most common Safe-T-Cable™ material. It is used for most engine and airframe applications. Inconel 600 (AS3509) is appropriate for high temperature and/or non-magnetic applications, and the new Inconel 625 (AS3655) has superior corrosion resistant properties. Consult DMC for further material selection information.
The pre-assembled cables have a square formed end cap securely attached to one end. This provides a positive stop when threaded through a fastener. The other end is electrically fused such that it will easily thread through the series of fasteners that are to be secured. The flexible cable material is lightweight and easy to handle. The stainless steel materials will not corrode or deteriorate while in use. (See chart on the following pages for material, size, and part number.) All Safe-T-Cable™ kits and assemblies are supplied 50 pieces per package.
FERRULES AND CARTRIDGE LOADING SYSTEM
The individual crimp ferrules are preloaded into a disposable cartridge unit (50 pieces per cartridge) which