Cutting pliers are a type of handheld and human-powered tool that magnifies the strength of the user's hand to allow him to cut through strong materials. A pair of cutting pliers, like nearly all pliers, relies on a lever and fulcrum system to transfer amplified power to the working point of the tool. The handles act as a lever, magnifying the user's grip. The point where the two parts of the pliers come together is a fulcrum, moving amplified power to the smaller cutting end.
Humans have used pliers for thousands of years. The process of smelting and forging metal is nearly impossible without some form of tool to hold the hot materials. This tool was usually a pair a tongs, which is a type of plier. Since those days, the types and variations of pliers have continued to increase. Today, there are many recognized styles of pliers; four of them are varieties of cutting pliers.
Lineman’s pliers are cutting pliers used primarily for cutting wire. These pliers have a heavy construction that can withstand abuse, twisting and bending. They look like a heavy-duty pair of normal pliers, but they have a flat end and a cutting section below the gripping area. Lineman’s pliers always have insulated handles to protect users from shocks. Some types of pliers have several layers of insulation to allow users to see when one layer cracks or wears through.
Diagonal pliers are for cutting only. Where the lineman’s pliers still have a gripping area, diagonal pliers do not. These pliers have contoured handles to allow users to put maximum force on them without hurting their hands. The working end of the pliers only contains a cutting edge that runs in the same line as the handles. The pliers get their name from the diagonal shape of their two cutting edges.
Pinching pliers work in a similar way to diagonal pliers, except the cutting edge is perpendicular to the handles. This makes pinching pliers better suited for cutting off small amounts of material, such as the tail end of a wire or cord. Diagonal pliers work better for cutting large things, like cutting a wire in half so both ends may be worked on individually.
Needle nose pliers are likely the best known variety of cutting pliers. These pliers have contoured handles like the diagonal or pinching piers and both a cutting section and insulated handle like the lineman. They also have an elongated nose that can slide into deep spaces where other pliers can’t reach. This allows them to pull wires out where they may be cut by the needle nose or by a more traditional set of cutting pliers.