How to weave car wiring harnesses. Tape for eliminating “crickets” and twisting wires into bundles. About electrical harnesses

It’s very nice that a girl has appeared among us. Her name is Elena. She is from the city of Rybinsk, Yaroslavl region. Here's what she writes about herself:

Good afternoon I want to write about electrical harnesses for cars and motorcycles. How you should and should not do it, about available materials, personal experience. I work as a design engineer, designing harnesses and electrical wiring for piston engines.

So, Elena's article.

About electrical harnesses

The tourniquet is a set electrical wires and cables that are used for communication various elements electromechanical or electronic systems.
The purpose of the harnesses is to provide power or transmit electronic signals to various peripheral devices. The harness consists of at least two wires.

Photo 2 – Harness on the mounting table (www.knaapo.com)

This is what professionally made car harnesses look like:

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Photo taken from the JDMParts blog on drive2.ru

This is what aviation harnesses look like (aer.interelectro.com.ua):

Materials and components for the manufacture of harnesses

The materials used in aircraft harnesses are highly reliable and can also be used military equipment. For example, heat shrink tubes from Raychem and Deray. After shrinking, they are quite soft (unlike cheap tubes) and resistant to abrasion.

Separately, it is worth mentioning the connectors used. For Russian technology, cylindrical and rectangular connectors are used, for example: SNTs, RSTV, ONTs-BS, 2RMD, 2RMDT (photo 6), in a metal case.

Any harnesses consist of the same components:

– wires (power and signal);
– connectors, tips, terminal blocks;
– protective materials (winding tape, corrugated and heat-shrinkable tubes, protective shells and stockings);
– harness fastenings (clamps, holders).
The difference in price between special materials and what we use for ourselves - at home or in the car - is severalfold.

There are many specialty electrical materials available, but they tend to be very expensive or rare. And often we simply don’t know what to use (this also applies to materials and tools) in a particular situation, and this is where the “collective farm” begins.

Wires for making harnesses

Where do we start? From the wires. When choosing, you must pay attention to the operating temperature, insulation resistance to gasoline, oil, and combustion resistance.

Let's take stranded copper wires in insulation of different colors and different sections, for example PV-3. They can withstand temperatures from -50°C to +65°C. They are quite common and are available in online stores and in retail sales. In fact, these were the only wires available in a wide range of colors and cross-sections that were found in a store in my city. Unfortunately, this is usually what happens.
(photo 7).

Photo 7 - Materials, tools and wires for the production of harnesses

Needs to be cut required quantity. You can measure the length using a rope or wire, laying it in place. It is necessary to leave a reserve in length for triple reconnection into contacts or lugs (several centimeters at both ends). After twisting, the wire will become even shorter, do not forget. The wire should not be stretched, especially near the connectors. If you are not sure, take a longer one; you will always have time to cut it.

In general, if the wires go together for at least 50 mm, they are combined into a bundle. It is prohibited to lay power and signal lines in one bundle. This means that wires from sensors and wires from powerful consumers must go along in different ways and as far away from each other as possible. An extreme case is a wire from some sensor and an armored wire from a spark plug.

The twisted wires can be secured with tape or a special thread. FUM tape is available for everyday use (in industry, fluoroplastic film SKLF-4D is used; FUM tape is also made of fluoroplastic, a non-flammable electrical material). The winding is carried out in the opposite direction of the laying. (photo 8).

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Photo 8 - twisted wires

Twisted wires are more flexible than simply folded together and covered with some kind of sheath.

The upper shell is corrugated, heat-shrinkable tube.

These are the most common materials used in private practice to protect wires. Sometimes they wrap the wire with electrical tape along its entire length, but this is not necessary. The glue will decompose over time (especially from heat), the wire will remain sticky, and in the end it doesn't look very good (photo 9).

The corrugation can be split or uncut (with a probe for drawing - wire). The split one can be put on a ready-made harness with installed connectors.

There is no need to fill the entire corrugation with wires, let a little remain free space(more details in paragraph 5.9 - GOST 23586-96) In the end, you may need to lay a few more wires. Sometimes they put spare wires in the harness; their ends must be covered, because The wire is a capillary pump, any liquid that gets inside will cause corrosion.

Photo 11 shows a method for sealing the insulation of a spare wire; it consists in putting a piece of heat shrink (the presence of an adhesive layer does not matter) so that at least a centimeter to one and a half centimeters is not put on the wire and treating it with a torch. Until it cools down, squeeze the free part of the tube with your fingers, it will stick together. All.

Application of heat shrinkage in the production of electrical harnesses

It would seem that the split corrugation is leaky, what is the use of it? It will prevent the wires from rubbing against sharp edges, unlike inexpensive heat shrink. There is a minus - the corrugation will not withstand high temperatures.

Instead of corrugation, the entire length of the harness can be covered with heat shrink.

Conventional heat shrinkage HERE has an operating temperature from -55 to +105°C, a shrinkage ratio of 2:1. This means that an 8/4 tube has a diameter of 8 mm before shrinking, 4 mm after shrinking. The closer the diameter of the bundle is to the diameter of the unshrinked tube, the smaller the wall thickness after shrinkage, therefore, it is worth choosing a tube so that the diameter of the bundle is approximately in the middle of these dimensions.

To shrink the pipe, you can use matches, a lighter, a torch, construction hairdryer. The main thing is to monitor the uniformity of shrinkage and not burn it out (for any tube the manufacturer writes the temperature of its complete shrinkage). It is inconvenient to do this with matches. Honestly. It is still possible to fit a small tube into the soldering area of ​​one thin wire, but not anything larger.

Professional option - (actually good thing, excellent for working with wood and leather when treating with wax, will help remove old paint, will heat up the part when replacing bearings). It has temperature control over a wide range, shrinkage occurs evenly and not too quickly.
I use soldering torch, it is refilled with lighter gas (photo 12).

The flame has high temperature, so you need to do everything quickly and carefully so as not to burn out the tube. I personally recommend purchasing such a torch; it will help when working with heat shrink, when soldering massive parts, and in other cases. But you can do without a hairdryer.

Branching of wires hidden in corrugation is carried out using a collapsible tee (photo 13)

I didn't have such tees. I had to use electrical tape, even though I don’t like it. The edges of the tubes are inserted into each other and carefully wrapped.

For branching, there are heat-shrinkable cable gloves (photo 15)

Photo 15 – cable heat-shrinkable gloves

It’s a great thing, but I’ve only seen these in retail stores once, and they were designed for large-diameter cables. If you are a fan of your craft, you will probably want to use these products. They are available in online stores (but you will have to search), for example, the KVT plant (Kaluga) will soon produce such products (I advise you to visit the KVT catalog on their website).

Removing insulation

Photo 16 – Stripper

This is done with a special tool – a stripper (photo 16)
He cuts the insulation, not reaching the core, but so that it can be torn off and moved. I strongly doubt that anyone uses such a tool in everyday life (for example, I don’t have one). Don’t listen to anyone who tells you “I use side cutters/nippers/knife to cut the insulation across the wire and remove it”; this is done at your own peril and risk; you cannot be sure that the blade has not reached the wire cores. It is very difficult to adjust the depth of the cut “by eye”.

That's what I do. But you need to be confident in your tool, hands and wire insulation! And after 10-20 such removals, calluses begin to appear! (Approx. SamElectric.ru)

One of the tools for removing insulation is a mounting knife, straight or with a heel (photo 17). With some skill, you can use a utility knife to insulate the insulation instead of a straight knife. The insulation is cut with shavings, as if you were sharpening a pencil, but being careful not to cut the wires.

I use a utility knife extensively. Especially when removing insulation from cables. To do this, I cut the external insulation lengthwise, trying not to cut the internal, individual insulation. And in a single wire I remove the insulation (when there are no wire cutters, or in difficult cases) by cutting the insulation around it.

Defense plants used insulation burners, which are similar to wood burning tools. Red-hot nichrome wire the insulation is burned in a circle and then removed. Suitable for both MGTF and other wires. In a similar way, you can remove the insulation using a soldering iron (photo 19). The downside is the smell and harmful fumes.

Photo 19 – Removing insulation with a soldering iron.

Photo 19-2 – Removing insulation with a soldering iron.

Soldering or crimping wires

In general, crimping is better in terms of vibration resistance. When soldering, at the point where the wires come out of the solder, they are most likely to break off if they are subject to vibration (photo 20).

A properly made crimp is stronger than the wire itself, but how many people have a crimp at home, at least for car terminals? That's right, no, neither do I (in general, the crimps look like this - photo 21). Therefore, we will solder.

I have both a crimper and a stripper. I already wrote about crimping wires with lugs.

Important: never use acidic fluxes when soldering wires, no matter how tempting it may sound. Because the wire is a capillary pump and you still won’t be able to wash out the remaining flux from there, no matter who tells you what. Corrosion will soon begin there.

It is convenient to use rosin dissolved in alcohol. Pour this solution into a bottle with a brush, such as a nail polish bottle.

It is convenient to use flux LTI-120 with a brush. Or rosin in a jar, I’m writing about it.

Connector housings

– protect the contacts inside from water and dust, provide mechanical adhesion of the connector body and the wire. There are sealed or non-sealed.
In photo 22, the connector worked for a long time without a casing, the wires were often bent and moved, the wires were partially broken near the contacts (the wires were connected by crimping, but the cause of the malfunction was precisely the lack of a casing).

Photo 22 – Connector without casing

Hermetic casings are made of heat-shrinkable materials with an adhesive layer. The same tube, just a different shape. You can easily use a piece of regular tubing, but the point is that the diameter of the back of the connector and the diameter of the cable have a very large difference that ordinary heat shrink with a 2:1 ratio will not cover. Simply put, it will fit normally on the connector, but the wire will dangle. You can look for a tube with a shrinkage ratio of 3:1 or even more. These exist, but they are more expensive.

23 – Heat-shrinkable connector casing

In photo 23, a piece of ordinary heat shrink was used, a corrugation of a larger diameter was taken (there are only 2 wires inside). It should be noted that the softening temperature of the corrugation is approximately equal to the shrinkage temperature of the tube, so you need to work with the burner quickly and carefully, trying not to overheat anything.

Photo 24-1 – Before and after

Photo 24-2 - New electrical harness installed

Sealing

If necessary, special mastic is poured inside the casing to seal the contacts. In private practice, you can use silicone automotive sealant. A large volume will take several days to dry. If this is really necessary, try to be patient and pour it in parts, or at least coat the critical parts with a thick layer.

Important: Never use acid-curing sealants; corrosion will follow.

If you open the tube and the smell of acetic acid hits your nose, do not use it. If it doesn’t smell like anything, you can use it, it’s neutral, alcohol-based.

As a rule, acid sealants are cheaper (ABRO, RUNWAY); an honest manufacturer will indicate on the packaging “Contains acetic acid.” If there is no such inscription, carefully read the composition and Google each of the components. The sealant I bought contained methyltriacetoxysilane - this is a reagent for vulcanizing rubber, synthesized using acetic anhydride (I do not claim that this component is found in absolutely all acid sealants, please pay attention to the composition when purchasing).

After opening this tube, it began to smell like acetic acid, although the manufacturer indicated that it can be used for electrical connections. Let's not tempt fate; we'll leave it for less responsible nodes.

Laying the harness

The installation order is as follows:
– place the tourniquet in place, temporarily secure it with ties;
– connect all electrical connectors;
– we fix the harness in place, starting from the connectors (for example, from the ends of the harness, where the smaller terminals are to the large common connector).

The harness is secured in place using nylon cable ties. By the way, black ties are more resistant to external influences.
In photo 27 on the left you can see 2 metal clamps that secure the wires to the frame. They can be used, but on condition that the clamp does not fray the wire - wrap it locally with electrical tape, put on a piece of heat shrink, or put something under it. Do not forget that the harness should not be tensioned at the connectors and should not touch sharp corners, hanging around too much or touching very hot parts.

What if the harness goes into the box and connects there?

This situation simply arises when connecting a brake light:

The black thing with a union nut in photo 28 is a plastic cable gland (gland). It is designed specifically for inserting cables into various boxes. This thing costs no more than 20 rubles (for small wire diameters). There are metal cable glands (for harsh conditions and critical connections), but in stores they are, at best, made to order, the cost is already about 100 rubles per piece. In addition to the bushings, there are special penetrations and bushings.

Photo 29 – Disassembled cable gland on a wire

The wire is dangling in the connector (or anywhere), what else can be done?
If winding with various electrical tapes (PVC or fabric) and securing with clamps does not suit you, then...

There is such a wonderful thing - silicone tape LETSAR - electrical insulating tape, heat-resistant, self-adhesive rubber radiation vulcanization. This is a self-adhesive tape that vulcanizes when room temperature. After two days, you get a piece of relatively soft rubber where you wound it.

In aviation harnesses, it is just wound under rigid metal casings for better compression. I won’t describe the properties in more detail, there’s too much text. Sold in 500 g spools, it stretches greatly when wound, the spool will last a very long time.

In general, it’s worth looking for self-adhesive (self-vulcanizing) tapes from other brands, where the packaging is smaller.

• OST 1 00723-74 Connecting negative wires to the housing aircraft. Technical requirements
• GOST 23585-79 Electrical installation radio-electronic equipment and instruments. Technical requirements for cutting and connecting wire shields
• GOST 23586-96 Installation of electrical radio-electronic equipment and devices. Technical requirements for harnesses and their fastening
• GOST 23587-79 Technical requirements for cutting installation wires and fastening cores
• OST 1.01025-82 Shielding of wires, harnesses, cables and metallization of aircraft. General technical requirements

Cable tie supplement

It is more practical than plastic ties (clamps) and electrical tape. The main advantage is that it is reusable!

It's easy, cheap and beautiful to tidy up the wires inside your electronic structure.
All you need is an empty soda bottle, scissors and a teapot. Read on to find out how to do this.

While disassembling factory structures, everyone probably saw that the wires were tied into bundles.
IN homemade structures this is rare. It often happens that behind a heap of assorted wires, the boards and other elements of the circuit are barely visible. Often such a heap of wires can be seen inside the computer system unit, where wires from the power supply and signal buses fill the entire internal space and impair the cooling of components; often a dangling wire stops one of the cooling fans, which leads to overheating and failure of expensive components.

Using the example of making a braid for the wires of a computer power supply, I want to show how to quickly and cheaply tie the wires of your electronic structures into bundles at home; in this way, anyone can tidy up the wires inside their system unit.
So what do we need.

Empty plastic soda bottle. I used a toxic green bottle of Mountain Dew. This plastic glows brightly in ultraviolet light. To decorate the inside of a system unit with a window on the side surface and UV backlight lamps inside, there’s no better way to think of it. Any bottle of the color you like will be suitable for tying into a wiring harness inside an amplifier or some other structure.
Cut off the neck of the bottle and use scissors to cut a narrow ribbon approximately 3-5mm wide in a spiral.

Next, we tightly wrap the wire harness with the resulting tape. To prevent the tape from unwinding at the ends, we secure it with temporary wire ties. You can use nylon ties or pieces of heat shrink tubing. You need to wind it turn to turn, pulling it as tight as possible.

And now the most important thing. Surely everyone knows that the plastic from which the bottles are made has pronounced heat-shrink properties. If you don’t know, then just try pouring boiling water over the bottle to make sure of it. After wrapping the wiring harness with tape cut from a bottle, this tape must be warmed up. I used a hairdryer adjusted to supply air at a temperature of approximately 130C*. If the wiring harness has not yet been unsoldered, or you decide to refine the wires from the computer power supply in this way, then you can use the hot stream of steam coming from the spout of a boiling kettle. Just be sure to dry thoroughly afterwards to remove any condensed moisture.

The rest of the photos were taken with UV light in a darkened room to make the braid stand out better.

After heat treatment, the braid will shrink, tightly envelop the wires and fix its shape, and will no longer try to unwind. The wire ties that secured the ends of the tape can be removed. Wires in such a braid become rigid. They are easy to give the desired shape and hold it well.

I hope this one is simple and cheap way will allow you to clean up the wires inside your electronic devices and may be useful to someone for decorating the interior of your system unit or some other device that has transparent windows in its walls. Good luck!

Very useful and necessary household wire harnesses can be made from a plastic bottle. The bundles can be of almost any size and any number of wires can be laid in them. I recommend that everyone who has a computer at home take note of this master class. Because thanks to it, you can easily organize order around your PC, where bundles of wires are always lying around.
Of course, the use is not limited to this. The harnesses additionally insulate the wire, protect against mechanical stress, excessive bending, etc. So there are simply a lot of options for use and application. And the main thing is that everything is made from recyclable materials that no one needs - a plastic bottle.

Will need

• 5 washers.
• 2 screws.
• Wooden block.
• Nail.
• Blade from stationery knife.
• Some copper wire.

Making a twisted rope from a bottle

Cars are currently subject to high demands on build quality and reliability. Accordingly, every component and part of the car must meet these requirements.

An integral part of a car is electrical wiring (wire harnesses). A wiring harness is a finished product consisting of individual wires fastened together into a bundle, the ends of which are reinforced with contacts that are assembled into blocks or protective elements are put on them (tubes, rubber caps, covers). The wires are secured into bundles: with bandages made of adhesive PVC tape, cable ties (toothed clamps made of thermoplastic polymers); heat shrink tube.

A modern car has harnesses with total number about three hundred pieces of wire (and more often more), reinforced with various contacts. The reliability of such a complex product depends on several factors. First of all, these are increased requirements for the quality of components and materials. Which, in turn, is influenced by the choice of supplier and incoming inspection.

The next factor is the use of modern high-performance and precise production and control equipment that meets the requirements international standards. And finally, the most important reliability factor is the specialists involved in the production process. The quality and reliability of the product depends on their professionalism.

Automotive harnesses can be divided into: low- and high-voltage wiring harnesses (battery and starter wires are most often single, less often consisting of two or three wires).

Process The production of a wire harness is divided into several main operations: cutting wires, stripping the ends of wires from insulation, reinforcing wires with lugs or contacts, fastening wires into bundles (knitting), installing detachable connectors, quality control.

In order for you to better understand what components the wiring harnesses consist of and in what sequence they are used in their manufacture, we tried to give detailed description basic operations for the manufacture of harnesses and types of equipment used.

For a better understanding of the assembly sequence of any harness, in this section we will introduce general concepts bundle structures that will be encountered later in the text. The tourniquet can be divided into parts and given names.

• The trunk of the tourniquet is part of the tourniquet with the largest number wires collected in a bundle.
• A branch is a bundle of wires extending from the trunk of a bundle or other branch.
• A branch point is a place where two or more bundles of wires diverge at some angle(s).
• Tips are elements that allow installation and dismantling of a harness with cold contacts.
• Connecting devices are devices complete with lugs that allow the simultaneous connection of one or more pin-socket pairs.
• Protective elements are rubber products intended for mechanical and chemical protection the connection points of the tip or connecting device with instruments and other electrical equipment of the vehicle.

Operations for manufacturing a harness.

If you put together the elements that make up the harness, they would look something like what is shown in the photo (Fig. 2.) To assemble a harness from them, you first need to know the sequence of operations for assembling the harness. Below is the sequence hand assembled(Fig. 3) for a non-serial harness:

Wire cutting.

Wire cutting is carried out using hand tool or a wire cutting machine. Depending on the program for producing bundles, manual or automated cutting methods are used.

Bonding wires into bundles (knitting).

Wires into bundles are fastened with bandages made with PVC adhesive tape in accordance with GOST 16214 - 70, cable ties (toothed clamps made of thermoplastic polymers in accordance with GOST 22642.3-80) manually or using a special tool, welding the wires laid out on one plane to the fastening element made in the form of PVC tape or one of the wires of the harness, made in a zigzag.

By agreement with the consumer, wires in bundles can be protected and secured into a bundle with a PVC tube, wrapped with PVC adhesive tape, spiral tape or corrugated tube.

The PVC tube and spiral tape on the bundle must be secured with a bandage or other means that prevent its movement and unwinding, respectively. The ends of the corrugated tube are usually protected with a heat-shrinkable tube or special rubber covers, which are selected according to the diameter of the tube.

Bandages are also applied at each branch point and on the branches themselves so that the distance between the bands is no more than 250 mm, unless the distance is indicated on the drawing. A splitter is installed on the bundles in the corrugated tube at the branch point to prevent the tube from moving at the junction and to protect the branch point from mechanical stress.

Stripping the ends of wires from insulation.

Stripping of insulation is carried out automatically, when cutting with a measuring cutting machine, or manually using stripping pliers, depending on the harness release program. Application of machines and special hand tools guarantees high-quality stripping without insulation residues and without cutting copper wires.

Reinforcement of wires with lugs.

Reinforcement of wires is carried out by cold pressing, manually or semi-automatically. This method ensures reliable contact of the wire with the tip. The cross-section of the wire at the crimped tip has a “heart” shape. Each wire of the core is deformed, losing its round shape, filling the voids and thereby providing maximum area contact with the tip. To ensure high-quality contact, tips that comply with regulatory and technical documentation are used.

The use of modern presses provides a reliable mechanical connection, the breaking force of which complies with the requirements of GOST 23544-84 and is controlled by special devices.

In the manufacture of battery and starter harnesses, tinning is used after crimping. It provides better electrical contact, a more reliable mechanical connection and protection against corrosion. Excessive requirements for the quality of the connection between the tip and the wire are explained by the fact that the point of contact between the wire and the tip experiences an increased current load and thereby increases the heating of the contact area. During operation, this can lead to wire tearing, short circuits, or even fire of the wiring.

Installation of connecting devices.

After the wires are reinforced with lugs, connecting devices (blocks, connectors) are installed where they were provided.