Safety wire 1917294 222373114 2008-06-29T00:31:54Z 208.127.137.105 /* Safety Wire Pliers */ {{Nofootnotes|date=February 2008 {{Refimprove|date=February 2008}} {{Cleanup|date=February 2008}} '''Safety wire''' is common in the [[aircraft]] and [[racing]] industries as an extra precaution to keep vital [[fastener]]s from unintentionally loosening and parts falling off due to vibration or other forces. This function is often referred to as ''positive locking''. It also allows rapid and easy visual inspection of fasteners to ensure that they have been tightened. Safety Wiring of fasteners is often a requirement to pass technical safety inspections in racing. Safety Wire itself is available in multiple [[American wire gauge|gauge]]s and different materials, depending on the application. In consumer aircraft and racing applications, stainless steel wire is used, most commonly in .032" diameter, although other gauges are used for specific circumstances. Typically, safety wire is threaded through a hole drilled into a fastener or part, then twisted and anchored to a second fastener or part, then twisted again, usually with the aid of safety wire pliers. == Application == ===Principle=== There are a few techniques for different applications. Non-proprietary safety wire systems all work on the same principle, which is that the tension of the wire on the fastener prevents it from working itself loose due to vibration or other forces. The wire itself maintains tension and remains in place by being twisted around itself and attached to the fastener to be secured on one end and an anchor point (which could be another fastener) on the other end. Since safety wire is made of a [[maleable]] [[alloy]], it retains its shape after being bent, rather than springing back to its original shape. This property allows it to remain locked around an object, such as when it is passed through a small hole on a fastener and then twisted. Since it remains twisted instead of unravelling, it remains too large on the other side of the hole to be pulled back through. ===Installation=== Safety Wire Installation is a fairly simple task, but needs to be done properly to ensure proper security for the fastener in question. First, a length of wire is cut off of a spool. The length of the piece of wire to be used is determined by the distance from the location where the fastener to be secured is to be attached to another fixed location, which will act as an anchoring point for the safety wire. The wire should be cut to be slightly longer than twice that distance. The next step is to take the removable fastener such as a bolt, drill a hole through an accessible part of it, fasten it in the desired location, and then thread one end of the safety wire through the hole while taking the other end around the outside of the hole in the same direction as the end that is going through the hole. The wire is then pulled taut. Using Safety Wire Pliers or the twisting tool of choice (simple [[pliers]] can be used effectively, if not efficiently), the wire is then twisted at the optimal number of twists per inch. The wire is then released from the tool, and the two loose ends should be adjacent to each other at this stage. One of those ends is then threaded through some anchor point on the object to which the fastener being secured is attached. The other end of the wire is then threaded around the anchor point, and on the opposite side of the anchor point the twisting process is repeated. When finished, the loose end is cut off with a pair of diagonal cutters or wire cutters (many Safety Wire Pliers have a wire cutting feature), such that enough twists are left to prevent the wire from unravelling. The remaining end can have a sharp edge from being cut, so technicians will often bend it down against another hard surface to prevent it from damaging other components, such as electrical wiring insulation, or from causing injury to future technicians working in the area. ===Removal=== Safety Wire is removable, and removal is necessary to remove a fastener that has been Safety Wired. Safety Wire is removed by simply cutting it, untwisting it, and unthreading it from the secured fastener and the anchor point. Cut Safety Wire has sharp ends and users should be careful to not injure themselves or damage delicate components that are nearby. Any scraps from installation or removal should be disposed of properly. Although maleable, Safety Wire cannot repeatedly be deformed without breaking. Therefore, once used, Safety Wire should not be reused as it will be weaker than when first installed. ===Proper Techniques=== When using the most common gauge of safety wire, which is .032, the optimal number of twists per inch is 7 to 9. When using .041 or .040, optimal performance is achieved by twisting the wire 5 to 7 times per inch. On the smallest wire .020, 8 to 10 twists per inch is optimal. Equally important are the direction that safety wire is lead from the fastener to be secured and the choice of anchor point. The safety wire should be threaded through the object fastener such that it creates tension in the ''opposite direction'' of the fastener's removal. For example, if a standard automotive bolt in the U.S. is being secured, then the safety wire when installed should put tension on the bolt in a ''clockwise'' direction, since that is the direction that the bolt turns to tighten. When securing a single fastener, the anchor point for the safety wire should be a fixed point on the object. The fixed point should be something that will not move itself, and that will not be able to release the anchor end of the safety wire. It should also be free and clear of any moving parts that could damage the safety wire. When securing two or more fasteners, acceptable technique includes securing them against each other. In such a scenario, the safety wire is run through the first fastener (creating tension in the direction of tightness for that fastener), twisted, and then run through the second and subsequent fasteners such that the fasteners create tension, through the safety wire, in the direction of tightening for the adjacent fasteners. When implementing such a scheme, the location of the threading holes, length, tautness, and proper twisting (both the number of twists per inch as well as the direction of twist, which should alternate between fasteners between left-hand and right-hand twists) of the safety wire are all crucial to properly securing the fasteners. When drilling a fastener, the choice of where to drill it depends on the type of fastener and to what it will be wired. Some fasteners are best drilled through two sides of the head near each other, where as others are best drilled through one side and the top, and yet others are are best drilled through two sides that are opposite each other. The choice of where to drill a particular fastener depends both on where the fastener can tolerate being drilled while maintaining physical integrity and from what direction the securing force via the wire will be applied. The alternative to drilling holes in fasteners is to use Safety Wire Tabs. A Safety Wire Tab is a washer that goes around the shaft of a fastener and rests against the underside of its head. Safety Wire Tabs have sides that match the fastener being secured, except that they are larger. After the fastner is installed with the Tab in place, the sides are bent up, thus putting force on all sides of the fastener's head. Safety Wire is then run though the one side of the Tab that has a hole in it and secured per standard Safety Wiring procedure. The Safety Wire Tab transfers the securing force of the Safety Wire to the fastener and prevents it from rotating loose. == Tools & Accessories== ===Safety Wire=== Safety wire is commonly .020, .025, .032 or .041 inches in diameter and usually made of [[stainless steel]], but is also available in [[Monel]] and [[Inconel]] alloys for high temperature applications and copper for break-away applications. For consumer applications, it is typically sold in 1 pound spools enclosed in a small cardboard or plastic canister. ===Safety Wire Pliers=== Safety wire pliers come in three common sizes: 6, 9, or 12 inch(also called 7, 10, 13 inch, respectively, for manufacturers who choose to include the knob at the end of the pliers, which is used to actuate the twisting of the pliers, in the measurement). Safety Wire Pliers work as follows: The Technician grabs the two loose ends of the wire to be twisted in the end of the pliers; he then locks the handles of the pliers closed, which secures the loosed wire ends in the jaws; he then grabs the knob at the end the pliers, releases the main body of the pliers, and pulls back on the knob which causes the pliers to twist. The wire then twists. When the wire has been twisted sufficiently, the technician holds the pliers, releases the knob, and squeezes the handles of the pliers to release the locking mechanism, which loosens the jaws, thereby releasing the twisted wires. He then proceeds to the next fastener in the series or uses the plier's built-in wire cutters to trim off the excess wires. The final step is the push down the sharp end of the secured safety wire to eliminate any hazard from the sharp edge left from the excess being cut off. In addition to built-in wire cutters, some Safety Wire Pliers feature an angled or diagonal tip to their jaws which allows easier grabbing of wire. The angled tip is also useful for pushing down the sharp clipped end of the secured safety wire. Some models have a feature that catches the excess wire that is cut off. Safety Wire Pliers also vary in the direction of their rotation when the twisting knob is pulled, with some pliers rotating [[clockwise]], some rotating [[counter-clockwise]] (often called Right-Hand Twist and Left-Hand or Reversing Twist), and yet others have a selector function to allow the user to twist the wire in either direction without switching tools. The pliers can also be purchased with the option of the twisting knob returning to its position automatically or manually. ===Safety Wire Twisters=== A Safety Wire Twister is a simple tool that allows the user to grip the two loose ends of a piece of safety wire and then, while holding the main barrel of the tool, turn the end that is not gripping the wire (which is bent to create a simple cranking mechanism) in order to twist the safety wire. There is another type of basic Safety Wire Twister which is similar to a standard screwdriver, except that the tip has a small grasping mechanism to hold the ends of the wire while the technican turns the handle to twist the wire. ===Safety Wire Tabs=== Safety Wire Tabs are washers that are used to secure fasteners by transferring the force of the safety wire to the head of the fastener to be secured. The are installed just like any other washer, after which the sides of the Tab are bent up to make contact with the sides of the head of the fastener. One side of the Tab is longer than the other and it has a small hole, through which Safety Wire is threaded. Once the Safety Wire is properly installed, the sides of the tab transfer the force of the safety wire to the fastener, as though the fastener itself had been drilled and had the safety wire run though it. The advantage of Safety Wire Tabs is that the fastener to be secured does not need to be drilled, which can be advantageous for fasteners that should not or cannot be drilled because of size or damage concerns. They can also be useful when a fastener needs to be replaced, the replacement is not already drilled, and circumstances do not afford the time or tools to properly prepare the replacement fastener. ===Pre-drilled Fasteners=== For certain applications where Safety Wiring is common, fasteners come pre-drilled with holes to accept Safety Wire. When wiring something that did not come with pre-drilled fasteners stock, however, the more cost effective way (as opposed to replacing all stock fasteners with pre-drilled ones of the same type) is often to drill the stock fasteners. ===Drilling Jigs=== Because the use of twisted Safety Wire to secure fasteners requires the fasteners to be drilled, tool makers offer jigs to help technicians drill the fasteners to be secured. Although pre-drilled fasteners can be obtained, most fasteners to be secured start out never having been intended to be secured (e.g., a production motorcycle which was built for the street but which has been converted in to a race-bike). Such fasteners need to be drilled. Drilling them is often difficult as, due to their small size and irregular shape, securing them properly and applying a drill effectively can be trying. As a result, technicians often break drill bits or damage the fastener when the bit slides off position. A useful tool is a [[drill press]], because it allows the technican to apply the force of the drill bit directly to the fastener being drilled and eliminates lateral movement; but even with a press the fastener needs to be secured to prevent it from sliding out from beneath the bit. Even though drill presses ease the process, a press isn't always available, such as at a race event; and even with a press, the problem of securing the fastener still exists. To solve those problems, jigs are available which are designed to securely hold the fastener and provide a guide-channel for a [[drill bit]] (with either a hand drill or a press) so that the technician can easily and directly apply force from the drill to the fastener without having it slip off or breaking the bit. ==Safety== Safety Wire has sharp ends after being cut. It should therefore be disposed of properly when being scrapped. Technicians should also wear eye protection when cutting Safety Wire (particularly thick twisted ends) as the cut off ends tend to fly out from the cutter. Technicians should also take care not to cut their hands on the sharp ends, or to damage any sensitive components (e.g. electrical wires or assemblies) that are near the work area. ==Proprietary Methods== Some enterprising tool companies have devised Safety Wire mechanisms that attempt to simplify, ease, and expedite the process of securing critical fasteners. One example is [[Daniels Manufacturing Corporation]] of [[Orlando, Florida|Orlando]], [[Florida]]. Daniels manufactures a product called ''Safe-T-Cable'', which they advertise as, "The complete fastener retention system."<ref>[https://www.dmctools.com/default.htm Daniels Manufacturing Corporation<!-- Bot generated title -->]</ref> The Daniels system works by providing pre-cut lengths of Safety Wire that have a large cap on one end. The cable is threaded through a hole on the fastener to be secured, which is large enough to accommodate the wire but too small for the cap on the other end of the cable to pass through it. After the other end of the wire is passed through the anchor point, the technician takes an extra end cap and the special tool that is available from Daniels and crimps the cap on the other end of the wire. Again, the end cap is too large to pass through the hole that the wire passed through, and thus the cable is secured. ==Other Methods of Fastener Retention== There are also other systems of fastener retention that do not rely on Safety Wire at all, such as Nord-Lock's system of counter-locking washers,<ref>[http://www.nord-lock.com/default.asp?url=2.16.37 Nord-Lock - Products<!-- Bot generated title -->]</ref> safety pins, etc., all of which accomplish the same objective as Safety Wire, which is to prevent vibration or other forces from causing the undesired loosening of a mechanical fastener. ==Advantages vs. Disadvantages of Traditional Safety Wire== Although many systems purport to be more efficient than installing traditional Safety Wire, an advantageous by-product of the twisting method of installing Safety Wire is that it leaves a highly visible and easily inspectable indication that the fasteners in question are in fact properly secured. In addition, Safety Wire twisting is a standard, non-proprietary technique, and tools and materials can be easily found, cheaply purchased, and mixed with other brands while still working properly (provided of course that all components are used properly and with the proper ''types'' of complimentary components and tools, if not brands). ==See also== *[[Cotter pin]] ==References== {{reflist}} == External links == *[http://marrc.nova.org/html_docs/rrs.bikeprep.html#wiring (Racing Example)] *[http://www.byrongliding.com/lockwire.htm (another Aircraft Example)] *[http://volvospeed.com/Mods/safety_wire.html (Auto Example with Movie)] *[http://safetywirepliers.com (Safety Wire and Pliers)] [[Category:Safety equipment]]