Crimping pliers - a tool that provides reliable splicing of wires inside the sleeve or connecting the cable to the tip by crimping. The use of this tool in the activities of electricians increases the speed and quality of work, in contrast to the twisting of wires and crimping with pliers. Not only professionals, but also amateurs can use them, since ticks are easy to use.
When is crimping necessary?
It is especially convenient to use crimping pliers for ferrules, if you need to connect two stranded wires, because if you just clamp the unpressed cable into the terminals, then the cores will be compacted, a gap will appear between them, some wiring will be damaged and the contact will become weaker. Crimping pliers for lugs will provide a strong bond of the cores, thus eliminating the need to use single-core wires when laying power wiring.
It often happens that stranded wires with raw ends are screwed to the terminals. Several cores are damaged, and the remaining wiring cannot provide high-quality contact and burn out under heavy load. For example, when you turn on the RCD in the junction boxes. To avoid this, you need to put on the tips and clamp them with press pliers (crimpers).
What is crimping and why is it needed?
Crimping is a mechanical compression of wires in order to increase the conductivity of an electric current between circuit elements without overheating. Such a process reduces the likelihood of short circuit and burning of contacts. Not so long ago, the standard for the quality of the connection was twisting and soldering. This method provided solidity and minimal contact resistance, but was rather laborious. Crimping, which significantly saves time, is not inferior in terms of reliability, has quickly begun to take its place, and the traditional method of tinning wins in accuracy.
Insulated Tips
NShVI are used to process the ends of multicore cables for connecting RCDs, electric meters, terminal blocks. The abbreviation corresponds - the pin pin sleeve insulated. In other words, this is a fitting for a multicore cable prepared for installation in a terminal by tightening it with a screw. The use of such fittings for rigid single-core cables is not allowed - for them there are uninsulated caps. For compression, crimping pliers for insulated tips are used.
Two-profile jaws simultaneously compresses the electrically conductive part and the current-insulated part. If you need to connect 2 wires to one twisted terminal to the device, then you need to take NShVI-2. It has a larger width insulating skirt designed for two wires. The need arises when connecting circuit breakers or sockets in an electrical panel. Crimping is identical, as is the case with a single cable.
The selection of tips occurs according to the thickness of the cord. Stripped wires should fit easily in the groove, but not fluctuate in it. This is the key to effective contact after squeezing. The dimensions of the bushings correspond to the colors of the insulating skirts, and to the point on the crimping pliers. For tips, for example red, wires with a cross-sectional diameter of 1 mm are suitable and are inserted into the crimper matrix under the red dot.
KVT is one of the standard cable lugs. Copper, tinned, designed for wire processing. Crimped by hydraulic crimping pliers. For KVT lugs, one can find application in the manufacture of grounding tires.
Preparing the cable for crimping
Before crimping, the following work:
- Strip the conductors from insulation according to the length of the conductive part of the lug. It is preferable to use the stripper tool designed for this purpose - these are crimping pliers for tips with the possibility of removing the insulating layer for smooth stripping without damaging the fibers.
- With a sharp knife, carefully peel the varnish from its bare ends. Treat with special contact grease to reduce friction and maintain fiber integrity during crimping.
- Insert the wire into the ferrule so that the small wires all enter the socket and do not bend. Twist, as is done with tinning, is not necessary. Since, upon subsequent crimping, the wires pass each other and become damaged, therefore, the conductivity will decrease. You can only slightly connect with your fingers, without violating the parallelism.
- Pick up the sleeve according to the thickness of the section.
- Place the tip on the crimping pliers. For caps of a specific color, observe the corresponding color mark on the instrument. For example, the compression of the yellow tip is performed by the notch of the matrix indicated by the same color.
How to correctly crimp
To obtain a high-quality crimp, you must adhere to the rules:
- Hold the cable in the socket while squeezing with pliers so that the wires do not come out of the sleeve.
- Squeeze the tool handles until the ratchet device engages. It is needed to prevent the unclenching of the handles. In case of an error, the ratchet must be released, remove the tip from the jaws of the tool, cut off the marriage and start work again.
- Using a tool without a ratchet, control the clamp with your hands while slightly moving the wires. With a good crimp, the cores do not hang in the nest.
- Squeeze the metal part of the tip first, and then the insulating part if using a single-circuit die tool.
You can check the crimping quality by pulling the wire from the socket with your hands. He must sit tight.
Splicing cables with sleeves
If it is necessary to connect two electrical wires, a sleeve is used in which the ends of the two cables are fastened by crimping. The use of sleeves provides excellent electrical contact and greater mechanical strength. To accomplish this task, crimping pliers for sleeve tips are used.
With this tool, you can squeeze the sleeve over the entire length in several steps, as far as the width of the matrix and the size of the sleeve allows. The sleeve material should be the same as the cable. For example, copper wires are fastened only with a sleeve of the same metal, with aluminum similarly. If it is necessary to connect the copper and
aluminum cables end-to-end, an
aluminum- copper sleeve is used.
Crimping is done in two ways:
- point indentation;
- continuous compression.
When preparing the ends of the cables, contact grease is used to prevent oxidation of metals; moreover, aluminum wires should be stripped to remove the formed film.
With a shaped press, the wires are crimped to a round shape, after which they are inserted into the sleeve until they stop. Connections are either end-to-end when the wires are directed in the opposite direction from each other, or as a tip when the cables look in one direction. Continuous crimping tools are not suitable for the case of butt contact, since after crimping it will not be possible to remove the pliers from the wire.
After crimping, the contact point must be insulated with a heat shrink tube. It is necessary to put it on the cable in advance and move it to the squeezed sleeve, heat it for shrinkage. It is allowed to use electrical tape.
Large cross-section sleeves
Massive sleeves are very difficult to fit with crimping pliers. For sleeve tips 95 mm2 and more use hydraulic presses. In them, the work of the hands is enhanced with the support of the hydraulic system.
Common crimping errors
Beginners in the profession or amateurs often make typical mistakes:
- The inner diameter of the sleeve is smaller than that of the wire. To put such a wire in the sleeve, excessive compression of the cable is made, which leads to the destruction of the cores. Consequently, the resistance increases.
- The cross section of the sleeve is much thicker than the cable. This contributes to poor contact, will not even help to fold the wires several times, as it reduces mechanical reliability.
- Short sleeve. When, in order to save, they cut the whole sleeve in half. This will lead to an increase in resistance and unstable compression due to the small compression area.
Using a hammer and pliers to compress will destroy the sleeve and the wire itself. It is necessary to use crimping pliers for cable lugs, they make work as easy as possible.