Kevlar cable. Industrial optical fiber. Kevlar protective clothing

There is no one universal technology for cutting a fiber optic cable for installation. Each coupling has its own specifics, which are specified in the instructions for it. It may be necessary to completely cut off the Kevlar threads, or vice versa, leave and clamp them in the mount, cut off the strength element, or vice versa, provide for its sufficient length.

General advice - be sure to observe the prescribed length of the fibers released during cutting, do not make them too short. Otherwise, installation will be difficult.

At the same time, each stage of cable cutting has its own practical nuances - that's what we'll talk about today. And let's start with the tools that are used by professional fiber optic installers and shareholders.

Tools for cutting optical cable

The main arsenal of the assembler-solber of fiber optic networks for cable cutting:

• Stripper knife;
• Stripper clothespin;
• D-Gel hydrophobic lubricant solvent;
• Pliers;
• Model knife.

As well as side cutters, ties, a vial for alcohol, screwdrivers and other tools. On sale there are special suitcase sets for working with optics, for example, NIM-25:

Cutting and installation of an optical cable into the sleeve in stages.

The first thing to do if the cable has been stored for a long time in a humid environment without end waterproofing is cut and discard approximately 1 meter of cable. Optical fiber and other structural elements lose their qualities with prolonged exposure to moisture.

This is especially true for optical cable reinforced with Kevlar threads. They perfectly absorb and "transmit" moisture for many meters. Subsequently, if such a cable is laid next to high-voltage lines, moisture in Kevlar will become a current conductor and, as a result, cause damage to the cable.

Outer sheath and cable

To cut the outer sheath, we use a stripper knife - either a standard one for fiber optics, or one that is used to cut a power cable. We set the desired thickness of the cut, fix the knife on the cable and turn it around the axis several times (5-10). It turns out a circular cut. Now we make two longitudinal ones from it in the direction of the end of the cable - and the sheath breaks into 2 halves.

Important:

• The thickness of the cut must be exactly set.. If it turns out to be too deep, there is a risk of cutting the optical fibers, or dulling the knife blade on the armor. The most unpleasant thing that can happen here is that after welding and finishing the installation into the sleeve, you will find that one of the fibers jumped out of the cable, because. was damaged by cutting. If the incision is small, you will have to spend time to tear off the shell.
• When working with different types of cables, always try a cut on the tip of a new cable.- to check if the cut thickness is set correctly.

The cable for suspension in cables of the "eight" type is cut with cable cutters, its sheath is separated from the main sheath of the cable with a knife.

Cutting armor, corrugated armor and Kevlar

Depending on the type of coupling, the Kevlar, corrugated or wire armor may need to be cut out incompletely, leaving some part for fastening. Also, armor and corrugated armor can be used to ground the cable - you will also need to leave a small segment.

Inner shells and hydrophobic impregnation

To cut the inner sheath (not all cables have it), use:

• Ordinary dummy knife (requires good experience and skill, because there is a high risk of damaging modules with fiber optics);
• The same stripper knife as for the outer sheath, but set to a different cut thickness. We act very accurately and accurately, because fiber is getting closer;
• Clothespin stripper.

It is best to keep two stripper knives on hand - one set to the outer sheath of the cable, the other for a thinner cut of the inner sheath.

Now the installer is left with modules with fiber optics, covered with a film, interlacing of threads and hydrophobe (all this together, or in different combinations). We work with gloves, because hydrophobic lubricant is a very unpleasant liquid that is difficult to wash off your hands.

• A thin film, if any, is easily cut with a knife;
• The threads are removed manually or with a special hook, which is on some models of stripper knives;
• We take napkins, D-Gel (“orange”) liquid - it can be replaced with gasoline (if we work outdoors) and carefully clean the modules from everything;
• After general cleaning, we also clean each module separately, and then wipe it with alcohol.

Some use a faster and "cleaner" method: do not cut the cable to the modules completely, cleaning only small plot, from half a meter. On him bite the shells of the modules and pull everything together- modules, threads, film, etc. - like a stocking. However, while saving time, this method is fraught with damage to the fibers if the applied force is too great. This is especially dangerous in winter, when the hydrophobic lubricant thickens.

Dividing the modules

If the fiber optic cable is monotube and its module is made in the form of a hard plastic tube, a circular incision is made with a small pipe cutter and, carefully, so as not to damage the fibers, the module is broken.

In the case of the presence of several modules, everything is more complicated. First, while you are working with one, you need to hold on to the others that are actively crawling under your arms. Secondly, the cable itself is on weight and it is not very convenient. It is best to do this work together.

We cut empty stub modules under the root. We bite modules with fiber optics with a special module stripper. Again, it is very important to choose the correct depth of cut, so what? That's right, an optical fiber in the immediate vicinity of the instrument.

Important:

• The module stripper has a special pawl that blocks the reverse. It often happens that it works just at the moment of biting the module. You cannot open the stripper back, the only way to release the latch is to bite the module again, which is fraught with damage to the fibers. Therefore, the position of the latch dog must be monitored.
• You can not pull the modules from the fibers with great force, this can damage them and affect the quality of communication in the future. It is better to release slowly, in parts.

Fiber cleaning

Fibers intended for installation and welding must be perfectly whole and perfectly clean. First, we wipe them in the following sequence:

• Lint-free dry wipes - 3-4 pieces - remove the hydrophobe;
• Lint-free wipes moistened with alcohol (ethyl, isopropyl).

Expensive wipes in practice are often replaced with high-quality toilet paper (unflavored).

The fibers are then carefully inspected for integrity. Even if the lacquer coating is damaged quite a bit - it is better to cut the cable again. The time investment will be much lower than if you have to come back here after a while and repeat the fiber optic cable splicing process from start to finish.

Sleeve mounting

Before inserting the fiber optic cable into the sleeve on it heat shrink must be worn(with the exception of those designs where the cable is fixed in raw rubber). This is a polyethylene tube, which, under the influence of high temperature, “shrinks” and tightly wraps around the cable and the coupling pipe. This seals the cable entry. In addition, this is an additional fixation element.

Shrinkage is done after completion of work, tk. if something goes wrong during welding, there will be no need to waste time removing the frozen film.

Shrinkage can be done with a blowtorch, blow dryer or gas burner. In practice, it is very convenient to use the design of a tourist gas canister and a small burner.

Reading time: 4 minutes

Kevlar - name trademark high-strength polymer material(KEVLAR), developed by scientists from the American chemical company DuPont (DuPont). It surpasses steel in strength characteristics, but is much lighter in weight.

Kevlar was invented in 1964 by American chemist Stephanie Louise Kwolek while working at DuPont.

By 1971, a group of scientists from the company managed to finalize the material, and it began mass production.

Kevlar is an analogue of SVM and Twaron (which many do not know), created almost simultaneously in Russia and Europe. But since he was the first, all materials related to this group began to be called that way.

Production

Kevlar is produced in the form of:

• technical threads;
• yarn;
• roving;
• fabrics.

It is a crystallizable polymer. It is produced by the method of polycondensation in solution in low-temperature mode. Reagents are added to the solution, and the polymer is isolated from it in the form of a gel or crumb. It is washed, dried and dissolved in acid, then filaments and fibers are formed through spinnerets, fed into a precipitation bath, washed and dried again.

Kevlar properties

The usual fiber diameter is 1 µm, opaque.

1. The main characteristic of the material is its high mechanical strength. Density and, accordingly, mass are quite low.
2. Kevlar is stretch resistant.
3. It does not burn or melt, it has the ability to self-extinguish. Begins to decompose at temperatures above 430 °C. When exposed to high temperatures, it begins to lose strength only over time, not immediately.
4. Has resistance to organic solvents.
5. It has a high modulus of elasticity.
6. Resistant to corrosion.
7. Under the influence of very low temperatures (cryogenic) not only does not deteriorate, but also becomes even stronger.
8. It has low electrical conductivity.
9. Cut resistant.

Application

Initially, the goal of the developers was to create a lightweight, but very strong fiber that could be used in the manufacture of tires.

Kevlar fabrics

They are usually produced in the form of a canvas in rolls called Kevlar-49. There are also other types:

• staple-kevlar - short cut fibers a little over six mm long. Strength properties are lost due to cutting, but barrier properties are preserved. It is used for the production of yarn, felt and non-woven products with high heat-insulating and vibration-insulating properties;

• flock-kevlar - chopped fiber (up to 1 mm), used to reinforce various resins.

Kevlar fabrics also have disadvantages:

• lose strength during abrasion;
• destroyed by ultraviolet light. Requires special resin coating.

Kevlar protective clothing

The reinforcing properties of Kevlar are used, including it in the composition of fabrics from which elements of protective clothing are made: gloves, separate inserts in a suit, knee pads, anti-puncture insoles, clothing sports group- for snowboarding, motorsports, etc. This fabric becomes resistant to cuts and punctures.

Kevlar gloves can protect against glass cuts, short-term exposure to flames and hot objects, while they are soft, elastic and breathable (according to appearance reminiscent of knitwear) and allow you to work with even the smallest details, as they do not violate the sensitivity of the hands.

Since 1970, the development of anti-puncture fabric for body armor was carried out, and then the production of light bulletproof body armor from several layers of Kevlar began. To ensure that the quality of the material does not deteriorate under the influence of water and ultraviolet radiation, Kevlar armor is coated with a waterproof fabric.

Other elements of protection against gunshot and shrapnel damage are also produced, for example, in armored vehicles.

Sport equipment

Skis, snowboards, helmets, boats and paddles made of Kevlar are extremely durable and lightweight.

Shipbuilding

Kevlar began to be used in shipbuilding relatively recently - the last two decades. The process of its production is high-tech and quite expensive, so it is used selectively - for finishing the hull along the seams, in the keel part.
It is used for the construction of yachts. From this material, they are very light, consume less fuel and are able to develop more high speed.

Find out from the video what Kevlar bags are and whether Kevlar fabric will suffer from a knife.

Other areas

• Kevlar is used as a reinforcing fiber to give the material strength and lightness. They strengthen the cables by threading a Kevlar thread along the entire length, protecting it from stretching and breaking.
• It is also used for the manufacture of orthopedic prostheses.
• Kevlar ropes are characterized by high strength, light weight, corrosion resistance, non-electrical conductivity, so they are widely used in shipbuilding and mining, where they replace steel cables.
• The strength properties of Kevlar fibers are combined with the heat resistance of carbon and a hybrid material is obtained - carbon-Kevlar. It is used to build boat hulls capable of high speeds.

Due to its high strength and resistance to external mechanical and chemical influences, Kevlar is widely used in various fields and is recognized as one of the most high-tech modern materials. Read about other high-tech materials.

Any cable can be subject to significant physical overload. This is especially true in cases where communications are laid not indoors, but along the street. Any such single-mode optical cable, the price of which requires significant investments, must have special protection against various atmospheric influences. These include high humidity, sudden changes in temperature, and sunlight.

As a rule, polyethylene is used as the sheath of fiber optic cables. Of course, it has a lot of advantages, but in terms of strength, it often shows itself from a not very good side. Therefore, in order to amplify single-mode and multi-mode optical cables, their design is strengthened with the help of power elements. These elements are made of Kevlar, which is known to be extremely durable. This is proved, for example, by the fact that this material is used to make modern body armor. Any reinforced optical cable is able to withstand significant impact without compromising the integrity of the entire structure and jacket.

Features of strengthening optical cables with Kevlar threads

Kevlar allows you to significantly increase the allowable stretch of the cable. With such a gain, the stretching can reach 1000-2000 N. Most often, this indicator is quite enough for any cable. general purpose. In other words, reinforcement is advisable not only if there is an optical cable for internal installation, but also for external. Reinforcement with Kevlar threads has gained wide popularity due to its high efficiency. It is also worth noting that the threads can intertwine with each other, or they can simply form a dense protective layer. Among other things, they provide a high tensile strength. Therefore, any similar single-mode optical cable, the price of which will be higher, can be used even in the most non-standard situations. The main thing is to correctly install optical communication cables.

Sometimes the cable is reinforced not only with threads, but also with special rods. They can be metal or dielectric. If a single-mode optical cable has a large number of fibers, then such an additional reinforcing element can be located in its center.

Thermal shrinkage.

As insulation in the manufacture of the cable, a heat-shrinkable tube of a certain type, color, diameter and thickness is used.

Two or three-layer thermal insulation technology can be used. With this method, it became possible to combine different types heat shrinks and a combination of different colors!

Managed to pick up transparent a heat shrink option that is very soft and stretchy. When using two or more layers of thermal insulation, the microphonic effect can be markedly reduced!

From here, the most stylish, beautiful and most popular option is the headphone cable in transparent performance, especially when he emphasizes the nobility of copper and silver. During operation, the transparent color may fade, especially when worn under clothing.

The advantage of using heat shrink is the possibility of "restoring" the cable in case of careless handling (scuffs, scratches, etc.), up to the complete "unweaving - interweaving" of the entire cable. The property of shrinking and straightening when heated, the heat-shrinkable tube withstands many times.

Also, heat shrink has a range of operating temperatures from -55 ° C to +125 ° C, which does not lead to to stutter cable in the cold (and over time it even becomes softer).

Teflon insulation.

Also, FUM Teflon tape can be used as conductor insulation, followed by "removal" into a common heat shrink. This option is relevant when the cable needs to be made as thin and soft as possible.

Winding Teflon tape on a copper or silver strand is a rather laborious process that requires accuracy and patience.

Kevlar thread.

Almost all manufacturers of headphone cables necessarily mention the presence of Kevlar threads or something similar for the strength and durability of the cable, but sometimes they are silent about the number of cores and their thickness.

As a result, the cable looks intact, and the thread is intact, but the conductor itself inside the braid is frayed or even rotted, and there is no signal, or it disappears. Even when the sound is present, it can already pass through only one surviving thin vein, here there is no need to talk about any acceptable sound quality.

Therefore, in the manufacture of my cables, I try to focus on more the amount of the conductor itself, rather than for additional protection of the cable for breaking. Although, for example, a strand of 34 copper veins with a diameter of only 0.06 mm is not so easy to break (it's like in the parable "about a twig and a broom"), not to mention when the copper or silver strand is also insulated . The different versions of combined hybrid cables (silver + copper) are generally unrivaled in terms of tensile strength.

It is also possible to use special additional braid on a ready-made cable (for the whole, or partially up to the jack). This is especially true for stationary headphones, various interconnects and adapters, where the thickness of the cable does not play a special role, but additional protection and a beautiful aesthetic appearance, yes!

Earplugs and earwires.

Many replacement cables have built-in wires that allow you to take and remember the shape of the ear behind the ear for a more comfortable fit and wearing.

With this method of wearing, the microphone effect may be practically absent.

There are problems that with frequent bending and unbending, the built-in wire does not withstand loads and breaks inside the cable. In this case, you can try to remove the broken wire, and sometimes you even have to change the connectors themselves for new ones.

In my cables I use more than thin(and, accordingly, softer) wire, which twists in a spiral of the conductors themselves, as if "merging" with them and becoming almost invisible. With this method, the "survivability" of the behind-the-ear wire is greatly increased, and allows more flexible adjust the cable to fit your ears.

Also, instead of the behind-the-ear wire, heat shrink (one or two layers) can be used again over the cable itself. With this option, it is enough to warm it up slightly (preferably with a hot air gun, but you can also over steam, or with an ordinary lighter, but not much) and give the shape of the ears you need.

Headphone connectors.

The main trouble with many connectors (those that are inserted into the headphones themselves) is loose contact with the sockets of the headphones themselves, which may cause the signal to disappear. And the most dangerous thing is that if the cable is not tightly connected to the headphone sockets, they can be accidentally dropped or even lost!This mostly applies to connectors like Westone and Ultimate Ears...

You can try to solve this problem in the following way:

In the manufacture (turning) of master connectors themselves pins are made with a margin and then with a fine-grained nail file or emery cloth adjusted for specific sockets of the headphones themselves (the main thing is not to grind off the excess). Sometimes this also applies to factory connectors, which initially may have a larger pin diameter than necessary;

If the connectors already have nothing to grind, then you can try them build up using solder (preferably with a silver content);

Instead of solder (or as an addition), you can use a thin silver-plated wire, a piece of which is placed in sockets under the connectors, the excess is cut off, and then the cable itself is inserted;

Another method associated with bending the pins of the connectors (pins) certain way.

Another personal development: instead of solder, conductive adhesive "Kontaktol" with silver is applied to the pins of the connectors, after which it is allowed to dry for about a day and can be used. Of course, with frequent removal of the cable from the headphones, the adhesive layer will be erased, but this adhesive has very little resistance, and when installed in the headphone jacks, it will still fill the micropores, thereby improving the signal conductivity characteristics.

For reference: d pin diameter for Westone - 0.78mm, for Ultimate Ears- 0.75mm

Jackie.

Of the variety of portable jacks, the most popular and convenient is the jack. angular forms.But here, alas, the choice is small (unlike direct options):

Neutrik NTP3RC, Neutrik NTP3RC-B

Fiber optic cable for indoor installation consists of a fiber in a protective braid, available in various modifications Simplex - Duplex, used for digital data transmission. RoHS compliant.
- attenuation: 190 dB/km

- structure: 980/1000
- POF diameter (mm): 1.0x1
- outside diameter over braid (mm): 2.2 - Simplex
- outer diameter by braid (mm): 2.2x4.4 - Duplex

Optic fiber cable for internal and external trunks consists of fiber in a protective sheath reinforced with Kevlar thread, available in Simplex - Duplex modifications, used for digital data transmission. RoHS compliant.
- attenuation: 190 dB/km
- transmission distance: max 70 m.
- structure: 980/1000
- POF diameter (mm): 1.0x1
- outer diameter over braid (mm): 5.0 - Simplex
- outer diameter over braid (mm): 6.0 - Duplex
- reinforced inner layer: Kevlar
- working temperature (ºС): -55 ~ +85

M.O.S.T.（MediaOrientedSystemsTransport） is a high-speed multimedia network technology optimized for the automotive industry. Can be used to work inside or outside the car. Serial data bus using ring topology and synchronous data transfer for audio, video, voice and data signals using plastic optical fibers (POF).
- attenuation: 190 dB/km
- transmission distance: max 70 m.
- structure: 980/1000
- POF diameter (mm): 1.0x1
- outside diameter over braid (mm): 2.3 - Simplex
- working temperature (ºС): -55 ~ +85

Microduct microtubes are made of high density polyethylene for individual installation of fiber optic cables in new or existing channels. Or for use in case of need to quickly change the route of fiber optic cables and can be upgraded to suit new types of cables.

POF connectors - patch cords are used for a wide range of industrial audio / video devices. The products are manufactured using high quality raw materials and materials, widely used for telecommunication data transmission or video system. Connectors, connectors and patchcords are produced in various modifications.