Pliers are widely used because they are capable of increasing the efficiency of human labor. Although sometimes they go unnoticed because we are used to seeing them everywhere, they are actually manual tools created using interesting techniques that include great advances, so it is worth knowing how their manufacturing process is.
The oldest version of the pliers is the pincers, which were created in approximately 2,000 BC, coinciding with the forging of iron by humans to create survival tools. The tongs allowed iron to be manipulated at high temperatures, to keep it stable on the anvil during the forging of weapons. In fact, the tongs of today’s blacksmiths are almost identical to those of that time.
Later, industrialization made it possible to make different versions of pincers and pliers, so there are currently around 100 types of similar tools that are used in almost all human fields. Also, new models continue to emerge for specific applications in large factories, so they are not available for home use.
Germany is one of the European countries with the largest production of pincers and pliers, exporting 50% of its total production to the rest of the world, which reaches approximately one million pliers each month, including the most popular ones, such as universal, cutting diagonal and the classic pliers for water pumps.
The physical principle in the manufacture of pliers
The construction of the pliers is carried out through a principle of physics called bilateral lever, where the lower force applied with the hands to the handles is transformed into a greater force on the cutting edge and the jaws of the pliers, making a movement of grip. The more you squeeze the handles, the tightening force multiplies. The idea in this case is to produce large forces, for this reason, the distance between the center of the rivet and the jaws must be very short, while the distance between the end of the handles and the rivet must be larger.
Other pliers are designed for simpler jobs, such as facilitating the assembly of electrical devices, collaborating in pressure mechanics, as well as electronic repair in general. In these cases, the multiplication of manual force is not so necessary, but they are indicated to facilitate access to complicated places in devices of different sizes.
What are the parts of the pliers?
To understand the manufacture of pliers we must know that they have three fundamental parts. In the first place, we find a pair of handles that are the ones that allow the grip system, these elements must be designed following certain ergonomic criteria, so that they can be easily manipulated by the user, in a pleasant and safe way.
Secondly, there is the central pivot or articulation system, which must have a sliding movement without play, which allows the pliers to be opened and closed even with one hand. In this case, we can technically speak of a reverse movement in a socket joint, however, we can distinguish between various types of joint.
The lying joint is a system where the two parts of the pliers are superimposed and are riveted, but without resorting to milling, as is the case with universal pliers, which have an embedded joint, therefore, half of the tool rotates around to the rivet but fitted into a recess in one of the handles. But, there is another type of joint called tongue-and-groove, where one part of the pliers has a slot where the other half fits, however these are more difficult to manufacture and are usually not made of alloy steels, so they are less resistant.
The third part of the pliers is the head that includes the jaws or the cutting edges, depending on the model. In this case, it is important that the shape of the fronts of the head is correctly rectified for a good grip system. In the case of pliers, the two cutting edges must be precisely matched and sharp to achieve a clean cut of wires and other items.
How is the manufacturing process of universal pliers?
First of all, it is important to know that the raw material, that is, the steel, is usually supplied in rectangular bars that are approximately 6 m long. These bars measure 26 x 10 mm and are cut into pieces with the help of an eccentric press, so that they are in the shape of the pliers that are going to be manufactured. In order to shape these pieces, a gas-powered forging furnace is used, which reaches a temperature of approximately 1,200 °C, when the elements reach a light yellow incandescence, they are bent and forged with hammers.
Each piece of incandescent steel is placed between the upper and lower die of the pile driver, it is raised approximately 1 or 2 meters and then dropped into the hammer, so that the piece is crushed in the mold to fill it, while the material What is left over is overflowed forming the burr that will surround the blank. To obtain the latter, once forged, it is deburred in a 20 to 30-ton press.
It is time to drill the rivet and countersink its head, in addition to milling the profile of the jaws, the joint, as well as the back of the edges. At this point the two halves of the pliers are placed one on top of the other, for riveting and alignment. For its part, the heads of the pliers are rectified for greater precision, either with machines or manually.
The hardening process of the pliers is one of the most important steps, since it allows the steel to acquire greater strength and durability. To achieve this, they are heated to a temperature of 800 to 900 °C, known as red incandescence, to immediately put them in oil. But that’s not all, they are also tempered, heating them at very high temperatures for 1 or 2 hours to achieve the necessary toughness.
Some of the best pliers also have a machining process, where they are chrome plated or nickel plated for corrosion resistance, while others even have plastic coating on the handles, which works as an insulator while making them more durable. comfortable.