Pliers are a hand tool used to hold objects firmly, or for cutting and bending tough materials such as wire. 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.

There are many kinds of pliers made for various general and specific purposes.

History

Pliers in the general sense are an ancient and simple invention, no singular point in history or singular 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. Today, pliers intended principally to be used for safely handling hot objects are usually called tongs. The number of different designs of pliers grew with the invention of the different objects which they were used to handle: horseshoes, fasteners, wire, pipe, electrical and electronic components.

Design

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. In distinction to a pair of scissors or shears, the plier's jaws always meet each other at one pivot angle.

The materials used to make pliers consist mainly of steel alloys with additives such as vanadium or chromium, to improve strength and prevent corrosion. Often pliers have insulated grips to ensure better handling and prevent electrical conductivity. In some lines of fine work (such as jewelery or musical instrument repair), some specialized pliers feature a layer of comparatively soft metal (such as brass) over the two plates of the head of the pliers to reduce pressure placed on some fine tools or materials. Making entire pliers out of softer metals would be impractical, reducing the force required to bend or break them.

Common types

Gripping pliers

• Lineman's pliers (combination pliers)
• Flat-nose pliers (duckbill pliers) With long, narrow, flat jaws, they are stronger than needle-nose pliers, but less able to reach into really confined spaces
• Round-nose pliers (snub-nosed pliers)
• Needle-nose pliers (long-nose pliers, snipe-nose pliers) which have long, narrow jaws for gripping in confined spaces
• Locking pliers (vise grips, mole grips)
• Tongue and groove pliers (Channellock pliers)
• Parallel pliers which have jaws (usually smooth) which come together in a completely parallel motion, as opposed to regular pliers which rotate until contact. This design is intended to increase the surface area on materials the pliers are used on, decreasing pressure and potential for causing indentations.

Special purpose pliers

• Wire-stripping pliers - cuts and removes insulation on electrical wire while leaving the wire intact
• Fencing tools - include a hammer, wire cutter and nail puller on one tool
• Circlip pliers (retaining-ring pliers) - used for fixing or loosening retaining rings
• Nail-pulling pliers - an adaptation of the end nipper used for cutting wire; the jaws may be asymmetric, allowing the nail to be pulled out with a rocking motion on the surface in which it is embedded.
• Breaker-grozier pliers (Glass-breaking pliers, grozz pliers)

Adjustable pliers

• Slip joint pliers, which are similar to combination pliers but whose pivot can be slipped between two holes when the jaws are fully open to change their sizecalled
• Groove-joint pliers (tongue-and-groove pliers, water-pump pliers, Channellock pliers) (see Slip joint pliers) with adjustable jaw sizes, that are designed to grip various sizes of round, hexagon, flat or similarly shaped objects

Cutting pliers

• Lineman's pliers (combination pliers)
• Diagonal pliers (wire cutters, side-cutting pliers , side cutters)
• Pinching pliers (end-nippers)
• Needle-nose pliers designed for gripping, but typically incorporate a cutter for convenience.

Crimping pliers

• For crimping electrical connectors (solder-less connections)
• For crimping metal rings or tags on livestock
• For crimping metal security seals on cargo carriers
• For crimping an impression on a document - as in a notary's seal
• For crimping laboratory vials
• For crimping bottles with atomizer tops, such as perfume bottles
• For crimping "crimping beads" used in jewelry making

Rotational pliers

• Developed by NASA engineers to enable an astronaut to turn a nut in weightlessness. The linear motion of the hand is converted to rotational motion to drive a socket wrench.

Gallery

Image:Pliers slip 01CJC.png|Slip joint pliersImage:Side cutters.JPG|Diagonal pliers or side cuttersImage:Linesman's pliers.JPG|Lineman's pliers or combination pliersImage:Pincers.JPG|PincersImage:Pliers crimp 01CJC.png|Electrical wire stripping and terminal crimping pliersImage:Crimper HDF200.jpg|Crimptool for N, R-SMA, TNC connectors for RG174, RG58 and HDF/LMR200Image:Crimping-pliers-pro-RJ-0a.jpg|Heavy duty crimping pliers with interchangeable RJ headsImage:Hand crimp tool MH-17 opening.jpg|Hand crimp toolImage:Hand crimp tool DX-1008 opening.jpg|Hand crimp tool for insulated terminals and non-insulated terminals; also has a wire cutter and stripper and screw cutters

References

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