Pliers are ahand tool used to hold objects firmly, possibly developed fromtongs used to handle hot metal inBronze Age Europe.[1] They are also useful forbending andphysically compressing a wide range of materials. Generally, pliers consist of a pair ofmetalfirst-class levers joined at afulcrum positioned closer to one end of the levers, creating shortjaws on one side of the fulcrum, and longerhandles on the other side.[1] This arrangement creates amechanical advantage, allowing theforce of thegrip strength 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 thefingers.
Diagonal pliers, also calledside cutters, are a similarly shaped tool used for cutting rather than holding, having a pair of stout blades, similar toscissors except that the cutting surfaces meet parallel to each other rather than overlapping. Ordinary (holding/squeezing) pliers may incorporate a small pair of such cutting blades.Pincers are a similar tool with a different type of head used for cutting and pulling, rather than squeezing. Tools designed for safely handling hot objects are usually called tongs. Special tools for makingcrimp connections in electrical and electronic applications are often calledcrimping pliers orcrimpers; each type of connection uses its own dedicated tool.
Parallel pliers have jaws that close in parallel to each other, as opposed to the scissor-type action of traditional pliers. They use a box joint system to do this, and it allows them to generate more grip from friction on square and hexagonal fastenings.[2]
There are many kinds of pliers made for various general and specific purposes.
Medieval pincers found in Hamburg-Harburg (15th/16th century)
As pliers in the general sense are an ancient and simpleinvention, no single inventor can be credited. Early metal working processes from several millenniaBCE would have required plier-like devices to handle hot materials in the process ofsmithing orcasting. Development fromwooden tobronze pliers would have probably happened sometime prior to3000 BCE.[3] Among the oldest illustrations of pliers are those showing theGreek godHephaestus in hisforge.[4] 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, andelectronic components.
The basic design of pliers has changed little since their origins, with the pair ofhandles, thepivot (often formed by arivet), and thehead section with the gripping jaws or cutting edges forming the three elements.
The materials used to make pliers consist mainly ofsteelalloys with additives such asvanadium orchromium, to improve strength and preventcorrosion. The metal handles of pliers are often fitted with grips of other materials to ensure better handling; grips are usuallyinsulated and additionally protect againstelectric shock. The jaws vary widely in size, from delicateneedle-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.
A plier-like tool designed for cuttingwires is often calleddiagonal pliers. Somepliers for electrical work are fitted with wire-cutter blades either built into the jaws or on the handles just below the pivot.
Where it is necessary to avoid scratching or damaging the workpiece, as for example injewellery andmusical instrumentrepair, pliers with a layer of softer material such asaluminium,brass, orplastic 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, thus reducingmuscle fatigue. It is especially important for factory workers who use pliers continuously and helps preventcarpal tunnel syndrome.
