Crimping pliers - a tool that ensures reliable splicing of wires inside the sleeve or connecting the cable to the lug by crimping. The use of this tool in the activities of electricians increases the speed and quality of work, in contrast to twisting wires and crimping with pliers. Not only professionals, but also amateurs can use them, as the pliers are easy to use.
When do I need a crimp?
It is especially convenient to use crimping pliers for lugs if you need to connect two stranded wires, because if you just clamp an unpressed cable into the terminals, then over time 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 bonding of the strands, thus eliminating the need to use solid wires when laying power wiring.
It often happens that stranded wires with raw ends are screwed to the terminals. Damage occursseveral cores, and the remaining wiring cannot provide high-quality contact and burn out under heavy load. For example, when turning on the RCD in junction boxes. To prevent this from happening, you need to put on the tips and clamp them with press tongs (crimpers).
What is crimping and why is it needed?
Crimping is the mechanical squeezing of wires in order to increase the conductivity of electric current between circuit elements without overheating. This process reduces the likelihood of short circuits and burnt contacts. Not so long ago, the standard of connection quality was twisting and soldering. This method provided solidity and minimal contact resistance, but was quite laborious. Crimping quickly began to take its place, which significantly saves time, is not inferior in reliability, and the traditional tinning method wins in accuracy.
Insulated tips
NShVI are used to process the ends of multi-core cables for connecting RCDs, electricity meters, terminal blocks. The abbreviation corresponds to - insulated pin tip. In other words, this is a fitting for a multi-core cable prepared for installation in a terminal by screwing it in. The use of such fittings for rigid single-core cables is not allowed - there are non-insulated caps for them. Crimping pliers for insulated ferrules are used for compression.
Double-profile jaws simultaneously squeeze the electrically conductive part andcurrent-isolated. If you need to connect 2 wires to the device in one twisted terminal, then you need to take NShVI-2. It has a wider insulating skirt designed for two wires. The need arises when circuit breakers or sockets in the electrical panel are connected. Crimping is performed identically, as in the case of a single cable.
Tips are selected according to the thickness of the cord. The stripped wires should fit easily into the groove, but not wobble 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 the dot on the crimping pliers. For tips, for example red, wires with a cross section of 1 mm are suitable and are inserted into the crimper matrix under the red dot.
KBT is one of the cable lugs standards. Copper, tinned, designed for processing wires. Crimped with hydraulic crimping pliers. KBT lugs can be used in the manufacture of ground busbars.
Cable preparation for crimping
Before crimping, the following work is carried out:
- Strip the insulation from the wires according to the length of the electrically conductive part of the tip. It is preferable to use the "stripper" tool designed for this purpose - these are crimping pliers for ferrules with the ability to remove the insulating layer for even stripping without damaging the fibers.
- Using a sharp knife, carefully scrape off the polish from the bare ends. Treat with special contact lubricant to reducefriction and maintain the integrity of the fibers during crimping.
- Insert the wire into the tip so that the small wires all fit into the socket and do not bend. Twisting, as is done when tinning, is not necessary. Since during the subsequent crimping, the wires will pass each other and be damaged, therefore, the electrical conductivity will decrease. You can only slightly connect with your fingers without disturbing the parallelism.
- Select the bushing according to the thickness of the section.
- Place the tip on the jaws of the crimping tool. For caps of a specific color, observe the corresponding color mark on the instrument. For example, compressing the yellow tip should be done by notching the die marked with the same color.
How to properly crimp
To get a quality crimp, you need to follow the rules:
- Hold the cable in the socket while squeezing with the pliers so that the wires do not come out of the grommet.
- Squeeze the handles of the tool until the ratchet is activated. It is needed to prevent unclenching of the handles. In case of an error, the ratchet must be unlocked, the tip removed from the jaws of the tool, cut off the scrap and start working again.
- Using a non-ratchet tool, control the clamp with your hands while slightly moving the wires. With good crimping, the cores do not hang out in the socket.
- Press the metal part of the tip first, then the insulating part if using a tool with a single-loop die.
You can check the quality of the crimp by pulling the wire from the socket with your hands. Heshould sit tight.
Splice sleeves for cables
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. Crimping pliers for ferrules are used for this task.
This tool can crimp the sleeve along its entire length in several steps, as far as the width of the matrix and the size of the sleeve allow. The sleeve material must be the same as the cable. For example, copper wires are fastened only with a sleeve made of the same metal, similarly with aluminum ones. If it is necessary to join copper and aluminum cables end-to-end, then an aluminum-copper sleeve is used.
Crimping is done by two methods:
- point indentation;
- solid crimp.
Contact lubricant is used to prepare the ends of the cables to prevent oxidation of metals, and aluminum wires should be stripped to remove the resulting film.
The wires are crimped to a round shape with a figured press, after which they are inserted into the sleeve until it stops. Connections are either end-to-end, when the wires are directed in the opposite direction from each other, or as a ferrule, when the cables look in the same direction. Solid crimping tools are not suitable for butt contact, as it will not be possible to remove the pliers from the wire after crimping.
After crimping, the contact point must be insulated with heat shrink tubing. It is necessary to put it on the cable in advance and move it to the squeezed sleeve, subject it to heat for shrinkage. Tape may be used.
Large section sleeves
Massive sleeves are very difficult to fit with crimping pliers. For sleeve tips of 95 mm2 or more, hydraulic presses are used. In them, the work of the hands is enhanced with the support of the hydraulic system.
Common crimping mistakes
Novices or amateurs often make typical mistakes:
- The inner diameter of the sleeve is smaller than that of the wire. To place such a wire in a sleeve, the cable is excessively squeezed, which leads to the destruction of the cores. Therefore, resistance increases.
- The cross section of the sleeve is much thicker than the cable. This contributes to weak contact, it will not even help to fold the wires several times, as the mechanical reliability will decrease.
- Short sleeve. When, in order to save money, they cut the whole sleeve in half. This will lead to an increase in resistance and an unstable crimp due to the small squeezing area.
Using a hammer and pliers to squeeze will destroy the sleeve and the wire itself. It is necessary to use crimping pliers for cable lugs, they make the job as easy as possible.
