Straight slip joint pliers are configured similarly to common or lineman's pliers in that their jaws are in line with their handles. One side of the pliers usually has two holes that are connected by a slot for the pivot. The pivot is fastened to the other side and shaped such that it can slide through the slot when the pliers are fully opened.
Tongue-and-groove pliers have their jaws offset from their handles and have several positions at which the lower jaw can be positioned.
Regular pliers with small jaws could be used to set a tooth. Designers added to this to make pliers with a built in stop. The stop is usually adjustable and rests against the saw blade as the jaws bend the tooth. The goal of the stop is to make a consistent set and prevent tooth breakage. Depending on the style, the tooth is either gripped first in the jaws and then bent or the saw set is aligned to the tooth and the jaws closed.
A plier-like tool designed for cutting wires is often called diagonal pliers. Some pliers for electrical work are fitted with wire-cutter blades either built into the jaws or on the handles just below the pivot.
There are many kinds of pliers made for various general and specific purposes.
The materials used to make pliers consist mainly of steel alloys with additives such as vanadium or chromium, to improve strength and prevent corrosion. The metal handles of pliers are often fitted with grips of other materials to ensure better handling; grips are usually insulated and additionally protect against electric shock. The jaws vary widely in size, from delicate needle-nose pliers to heavy jaws capable of exerting much pressure, and shape, from basic flat jaws to various specialized and often asymmetrical jaw configurations for specific manipulations. The surfaces are typically textured rather than smooth, to minimize slipping.
Pliers are a hand tool used to hold objects firmly, possibly developed from tongs used to handle hot metal in Bronze Age Europe. They are also useful for bending and compressing a wide range of materials. Generally, pliers consist of a pair of metal first-class levers joined at a fulcrum positioned closer to one end of the levers, creating short jaws on one side of the fulcrum, and longer handles on the other side. This arrangement creates a mechanical advantage, allowing the force of the hand's grip to be amplified and focused on an object with precision. The jaws can also be used to manipulate objects too small or unwieldy to be manipulated with the fingers.
Where it is necessary to avoid scratching or damaging the workpiece, as for example in jewellery and musical instrument repair, pliers with a layer of softer material such as aluminium, brass, or plastic over the jaws are used.
Much research has been undertaken to improve the design of pliers, to make them easier to use in often difficult circumstances (such as restricted spaces). The handles can be bent, for example, so that the load applied by the hand is aligned with the arm, rather than at an angle, so reducing muscle fatigue. It is especially important for factory workers who use pliers continuously and prevents carpal tunnel syndrome.
The basic design of pliers has changed little since their origins, with the pair of handles, the pivot (often formed by a rivet), and the head section with the gripping jaws or cutting edges forming the three elements.
As pliers in the general sense are an ancient and simple invention, no single point in history, or inventor, can be credited. Early metal working processes from several millennia BCE would have required plier-like devices to handle hot materials in the process of smithing or casting. Development from wooden to bronze pliers would have probably happened sometime prior to 3000 BCE. Among the oldest illustrations of pliers are those showing the Greek god Hephaestus in his forge. The number of different designs of pliers grew with the invention of the different objects which they were used to handle: horseshoes, fasteners, wire, pipes, electrical, and electronic components.
The three Pliers were later mass-produced as part of the Carpenters.
In the United Kingdom and Ireland, diagonal pliers are commonly referred to as snips or nippers, and in Canada, Australia and New Zealand they are often referred to as side cutters.
Lineman's pliers have a tapered nose suitable for reaming the rough edge of a 1/2" or larger conduit, or cleaning sharp metal from the inside of a standard metal knockout in an electrical enclosure such as a junction box or breaker panel. Some brands manufacture pliers (i.e. Ideal) with a narrower jaw, suitable for reaming smaller conduit.
Pliers started his career performing under the name 'Blues Melody', acquiring his more famous moniker due to an apparent similarity to fellow singer Pinchers.
Designed for potentially heavy manual operation, these pliers typically are machined from forged steel and the two handles precisely joined with a heavy-duty rivet that maintains the pliers' accuracy even after repeated use under extreme force on heavy-gauge wire. They usually have grips for better handling than bare metal handles; the grips may also provide insulation for protection against electric shock when working with live circuits, although most models are marked as not listed for such use. Some pliers are certified to withstand a specified voltage, e.g. 1000 V.
Some pliers for electrical work are fitted with wire-cutter blades either built into the jaws or on the handles just below the pivot.
Like most hand tools the durability and useful working life of pliers vary greatly according to load, frequency of use and the specific design and quality of the tool. They may be forged out of alloyed or unalloyed tool steel. For basic quality pliers unalloyed tool steel with a relatively low carbon content of 0.45% may be used. Top-quality pliers are typically made from higher carbon tool steel and alloyed with elements such as chrome, vanadium and molybdenum. In addition to being suitable cutting soft copper and aluminum, pliers may be specifically designed for cutting hardened wire, such as piano wire or nails, by induction hardening of the cutting edges.
Lineman's pliers can be used to bend or straighten sheet metal components, especially in cases where smaller pliers don't offer enough mechanical advantage. The square nose and flat side of Lineman pliers is particularly useful for creating accurate right angle bends. The durability of these pliers allows them to be used for tasks like removing nails and other types of fasteners.
Lineman's pliers may be used to cut steel screws up to #10, and virtually any dry-wall screw, although the thread form will be distorted. Lineman's pliers sometimes include an integrated crimping device in the craw of the handle side of the pliers' joint.