Crimping sleeves for crimping wires: types, characteristics, tools
Reliable connection of electrical wires ensures uninterrupted power supply. Sometimes on the wiring can be found twisted connections. Twist the two ends of the wiring oxidize over time and strongly heated by a large load. In addition, it is impossible to twist aluminum and copper conductors at all because of the electrochemical properties of the metal. The most reliable connection provides crimping sleeves.
What is sleeve testing and when is it needed?
Crimping is the process of connecting wires with special sleeves. Its essence lies in the use of metal tubes as a connecting mechanism. Inside the liner, on both sides, leads are made to connect the conductors of the wires. Compressing the tube with wires, get a strong connection. Crimping in domestic conditions is sometimes done with pliers, but it is better to use a specialized tool - press pliers.
The sleeve is compressed in two or three places, and the place of crimping must be insulated with a heat shrink tube or PVC insulation tape. Sometimes insulated connecting sleeves are used to connect wires. Then the need to isolate the connection is eliminated.
Crimping the wire with the sleeves should be carried out in the following cases:
- for connecting wires in lines with high load;
- if you need to connect the wires of large cross section;
- when it is impossible to use another type of compound. For example, the installation of wires inside the junction box, where it is impossible to place the terminal block or at high altitude with poor visibility.
The crimping process has its advantages:
- for compression of the tube using crimping press pliers. This hand tool does not require connection to the mains, as opposed to analogs intended for welding or soldering. In the absence of electricity, crimping is the only way to properly connect wires;
- to do welding or brazing, some skills are required. Make a pressure test tube each person can after the first test connection.The main thing is to have on hand a consumable material and press pliers, at worst - pliers;
- crimping tool has a comfortable working area. This allows operation in confined spaces such as podozetniki or junction boxes. Crimping the contacts inside the socket allows you to shorten the wires to a minimum, thereby increasing the density of installation.
In addition to these advantages, crimping allows you to connect wires from dissimilar metals, for example, copper and aluminum. Welding or soldering does not give such an opportunity.
The difference of the connecting tubes on the material
Crimping requires consumables, which are connecting sleeves. They differ in the type of metal used to make them. The use of heterogeneous sleeves due to the electrochemical properties of the metal. If the material of the wire, for example, aluminum, does not match the material of the sleeve, for example, copper, then such a compound will soon oxidize and there will be no conductivity.
The letter designation GM indicates that it is a sleeve, and it is made of copper. GM is used to connect only copper wire.GM does not have a protective coating, so it is used in non-aggressive environments.
The connection of copper wires, working in an aggressive environment, perform tin-plated sleeves. These are the same copper sleeves, only their surface is covered with a protective layer of white. They have their designation - GML.
The process of tinning eliminates electrochemical corrosion, but you cannot use GDF for aluminum wire. During compression of the liner, the protective layer is partially destroyed, which will lead to the contact of the copper with aluminum.
Tubes for connecting lived from dissimilar metals
Installation of electrical lines is not complete without connecting the cores of dissimilar metals. For these purposes, combined GAM liners are used. Their design consists of two welded tubes, one of which is copper, and the other is aluminum. In the middle, at the junction, there is a limiter. It is necessary for equal input lived on both sides.
Combined sleeves differ in shape. The fact is that the resistance of aluminum is greater than that of copper, and the conductor cross-section at the same voltage should be larger.Therefore, the aluminum part of the tube is increased in diameter.
GAM crimping is done in the same way, only on each side are the cores of the corresponding metal inserted.
There is a special design of insulated connecting sleeves. Their use eliminates the need for additional insulation of the compound with a heat shrink tube. Insulated sleeves are the same GML, only the top is covered with a dielectric PVC layer. The top coating is quite durable and has plastic properties. When pressure testing PVC layer is compressed simultaneously with the metal, but not destroyed.
The difference in diameter
Electric networks consist of stranded and single-conductor wires of different diameters. Naturally, for their pressure testing need connecting sleeves of the appropriate size. You can find out such parameters from the data table using the example of GM or GMP.
For the specified cross-section it can be seen that you can connect both single-core and stranded wires.
High-quality crimping is obtained only if all parameters are observed. If the conductors are thicker than the diameter of the tube, they simply will not go inside.An excessive diameter of the connecting tubes is also undesirable. After compression, the wires will have poor contact.
The size of the connecting tubes should be such that the cores inserted inside, without dangling, sit tight. In the absence of a sleeve of the appropriate size, thin strands can be connected with a thick tube. To do this, free space between the wall of the tube and the inserted core is hammered with pieces of lived from the same metal, and then crimped.
Previously, for crimping, some inventors used the traditional tool - a hammer, chisel or pliers. This is contrary to all the rules, but such an action is often rescued. Today we offer a tool of various modifications, designed for professional and residential use:
- hydraulic, assembly and crimping press pincers of various modifications;
- hydraulic and mechanical press. They may be manual or electric powered.
Opressovochny tool has a matrix. This figure element, which under pressure compresses the sleeve. The pressure on the matrix has a moving mechanism - a punch.In order to make the contact of the connection reliable, it is necessary to choose the interchangeable tool matrix correctly and crimp it under a certain pressure.
Conducting a large amount of electrical work with different cross-section of the wire requires frequent change of punch and die. Carrying a large number of interchangeable elements with an electrician is uncomfortable and difficult. For such purposes, there is a more convenient tool with one interchangeable punch or rotary dies of different sizes. To make adjustments for certain connecting tubes, the matrix is simply rotated to the other side and the required number of revolutions is made with a punch screw.
There is another, simpler tool for crimping without a die and a punch. They squeeze the connecting tube with braces.
The most common crimping tool used even in everyday life is press pliers. They are used to crimp the contacts of simple cables, non-standard connectors and other various terminals.
Depending on the destination, crimping press pliers are divided into two types:
- for removing insulation from the core;
- for crimping sleeves.
We will not touch the insulation removal, but consider a tool for crimping sleeves. Crimping design press mites has several types, different nests. The shape of the nest can be square or trapezoidal. The same shape is obtained and the crimp sleeve. More nests are distinguished by the presence or absence of plastic flanges. They make high-quality crimping stranded wire. To get a quality crimp connection, press the tongs should match the diameter, as indicated by the color marking.
Crimping press pincers are:
- The tool for insulated sleeves has three oval mold die presses. Each of them is marked in yellow, red and blue. Insulated tubes produce similar colors so that it is convenient to select the appropriate press. Working with such tongs it is necessary to ensure that during the crimping the joint edge is in the middle of the upper profile of the tool. The edge with side placement indicates poor contact and leaky fixation of the wire in the sleeve;
- The tool for uninsulated sleeves has a rod, which during crimping should be located at the separation junction.The tube itself is crimped in the center.
The choice of the type of tool corresponding to the section and the material of the connection to be made can be found in the table.
Crimping is a one-piece connection. To avoid installation errors, in which you have to cut the wire and throw away the used tube, you should have an electrical wiring diagram at hand.