Thread lock - to prevent it from unwinding. Loosen bolts and threaded fasteners from vibration Generate the required compressive force

KBV_NSK 08-09-2009 11:14

Good day, everyone
It started with the fact that the dovetail on the Di48 began to play. He didn’t want to give in to dismantling, so we have what we have. Namely: the standard screws are drilled out, the next thread is cut instead of them, and screws of a suitable shape are made. Everything is beautiful, the fin stands up and holds perfectly.
But there is a problem:
The screws were placed on Loctite, but it “does not hold.” I degreased everything, shook the bottle, smeared it carefully, and unscrewed it with literally two fingers, the effort of pulling it off was almost not felt. Repeated disassembly of the assembly showed that the Loctite had frozen as it should, but the screw itself could be unscrewed from it freely.

What else can you use to securely fix a screw in a thread? Naturally, you no longer need to unscrew.

bes_demon 08-09-2009 11:20

Tin it and screw it in while it's hot.
or the old grandfather's "Loctite" - rosin in alcohol.

KBV_NSK 08-09-2009 11:39

Any thoughts on 2-component epoxy, has anyone tried it?

tramblеr 08-09-2009 12:10

Do it as it was - rivet it from the inside.

KBV_NSK 08-09-2009 13:09

I thought about this too. But after the threads were cut and the screws turned out, everything turned out beautifully. Now it’s kind of a bummer to spoil and rivet everything. If it comes off, then of course I won’t bother a second time.

Strelok-mod79 08-09-2009 14:03

I glued the scale on VOMZ with epoxy - it holds tightly.

KBV_NSK 08-09-2009 15:08

Some friends here recommended it to me, perhaps I’ll try it for “cold welding.” The same 2-component epoxy with some fancy fillers. If you're interested, I'll post what happened.

kuznets 13-09-2009 22:59

I read somewhere that the screws that secure the dovetail on DIANAs are riveted at the manufacturer’s factory - they are immediately a permanent connection, and therefore cannot be unscrewed...

Turhon 14-09-2009 12:00

You probably loosened the thread a lot when you cut it.
I glued the strip myself in a similar case on the EAF

6aJIpoK 16-09-2009 12:54

You go to an auto store...you buy a “high-strength” thread locker there! and that's it! or baksitku + copper shavings finally tightly)

Storag 16-09-2009 12:55

What kind of Loctite did you use? Thread locker, glue or sealant?

dianarws 19-09-2009 01:01

quote: Originally posted by kuznets:
I read somewhere that the screws that secure the dovetail on DIANAs are riveted at the manufacturer’s factory - they are immediately a permanent connection, and therefore cannot be unscrewed...

That's exactly it, so you need to rivet it from the inside and polish it...
With such vibration, no Loctite/glue will hold...

KBV_NSK 21-09-2009 08:47

I glued it in the opschem and put marks (so I can see if it starts to unscrew). So far so good, I've shot 800-1000 and it's holding.
I’m writing - maybe someone will find it useful
In order:
-Loctite was exactly Loctite (from a car store), which is an “anaerobic thread locker”, maximum fixation, non-removable.

Cold welding - such as epoxy-based plasticine - is even worse than Loctite, there is no effect at all

As a result, I glued it to the usual 2-component epoxy “Contact” (of course, degreased everything and cleaned it of the remnants of other adhesives). After about 500 shots, I checked the marks - they were in place, I tried to unscrew them - the slots were torn off, the screw was in place. It seems to have worked out well.

Threaded connections are quite reliable and efficient. They are considered one of the most common and cost-effective. However, when exposed to vibration, there is a possibility of weakening them. This can often be seen in the example of nuts that loosen randomly during operation of various devices. Therefore, methods have been developed that can reduce this effect or completely eliminate it.

Ways to avoid loosening the nut

1. Using a washer. This method is one of the most common. It is used in the manufacture of household appliances and some types of industrial equipment. It does not have a high degree of reliability and is protected from arbitrary unwinding. A soft metal washer is placed on the thread, and then the nut is tightened, squeezing it out.

2. Washer and Grover. A more reliable method practiced by the transport industry. Protects the threaded connection from arbitrary unwinding even in the presence of slight vibration. First, a regular washer is put on the thread, and then a groover. After this, tighten the nut. The Grover here serves as a kind of spring, creating tension that prevents unwinding.

3. Special nut with lock. The method using a special nut cannot be called the most effective. However, it takes place in world practice and is used in some types of production.

4. Using thread locker. The composition is applied to the place where the nut will be located, after which it is put on the thread. This is a fairly effective way to prevent random unscrewing, but its effectiveness is affected by changes in temperature, high humidity and exposure to active substances. Therefore, its scope is limited.

5. Use of two or more nuts. One of the most reliable methods. Two nuts are screwed onto the thread at once. After clamping the first, the second is tightened separately, holding the first in its original position and even trying to unscrew it a little.

6. Fixation with a cotter pin. This is the most reliable method, able to withstand almost any external influence and strong vibration. It is used in particularly critical areas. The nut is fully tightened. Then, using a drill and a thin drill bit, a hole is made that pierces it along with the bolt. A pin is inserted into the resulting hole, the antennae of which are unbent, preventing it from falling out. Such a nut can be torn off only with a very strong rotational force in the direction of the thread.

The first mentions of threaded connections date back to the times of Ancient Rome, but they found active use only in the nineteenth century, when French engineers invented screw threads.

Almost immediately, the engineers encountered a problem: intense compression of the thread alone was not enough to securely fasten the structure. Exposure to external factors such as temperature changes or vibration can weaken connections, which in some cases can lead to very serious consequences.

For centuries, scientists have been looking for a way to reliably fasten a threaded connection. At first, all kinds of windings made from natural materials were used, but they could not withstand high pressure, temperature changes and contact with technical fluids. The result of the experiments was the invention of an anaerobic sealant, better known to us as a thread locker.

Threadlocker is a special class of adhesives that polymerizes at temperatures between 15 and 25 °C in narrow metal gaps (pores, threads, flanges and cylindrical connections) to form a durable layer that can withstand loads up to 3000 psi.

Please note that thread lockers are used only in metal-to-metal connections!

In other cases, the composition may not harden in loose threaded connections. In rare cases, a negative effect on the surface is possible. Do not use with PVC plastic.

The fixative is produced in a special thin-walled oxygen-permeable polyethylene container, so it can be stored for a long time without changing its properties even after opening the package.

There are two types of thread lockers in the ABRO brand range.

A clamp for connecting threaded parts that do not require frequent disassembly.

Suitable for fasteners up to 25mm diameter.

Seals the connection and imparts vibration resistance, quickly filling the space between the threads, providing the parts with a strong and tight connection, preventing loosening due to shocks and vibrations.

Seals threads to prevent rusting and corrosion.

Once cured, the fixative is non-toxic.

Temperature range of use from -59°С to 149°С,

Shear strength 3000 psi.

Today we'll cover where these threadlockers are used, how to apply them, and the difference between removable and non-removable threadlockers.

Thread locker blue (removable)

Blue (removable) thread locker can be used in a huge range of different activities to protect against vibration loads, as well as where it is necessary to replace spring split washers (grower washers).

Creates a strong elastic connection that does not lose its properties over time.

May be deleted.

Seals the connection and provides vibration resistance.

Resistant to most chemicals.

Suitable for fasteners up to 20mm diameter.

Easily removed using hand tools.

Dries in 20-30 minutes on most metal surfaces.

Complete hardening occurs within 24 hours.

Temperature range: −59°С…+149°С

Shear Strength: 1600 psi (112 kg/cm2)

Examples of using:

Fastening body elements subject to vibration.

Some car parts are subject to strong vibration. They can be securely fastened using blue thread locker.

Unscrew and clean the bolt from dirt or grease. Apply a little fixative to the threads.

We tighten the bolt into place and forget about the problem.

Repair of laptops and mobile phones.

Critical elements of computer technology are assembled in factories using blue anaerobic sealant. We recommend using the Blue Thread Locker (removable) when disassembling laptops, smartphones and other electronics.

Assembly of fittings for pneumatic systems.

Anaerobic sealants are used to seal fittings of pneumatic systems under high pressure. For example, a car's air suspension.

Extreme Sports

Thread locker is used when preparing equipment for extreme sports.

In particular, on slalom snowboards, where speeds reach 100 km/h.

Not only the speed characteristics of a snowboard depend on the reliability of the rider’s fixation to the board, but also controllability, the loss of which can lead to serious falls.

To avoid disastrous consequences, we will treat all the bolts connecting the boot mounting base and the snowboard with thread locker.

Thread lock red (non-removable)

Red permanent anaerobic sealant, designed for more aggressive use in mechanisms where very reliable fixation is required:

Fixing cylinder head bolts

Assembly of main pairs and gearboxes.

A critical element of the transmission that takes on the engine torque. Requires reliable fixation and 100% protection against unwinding .

Fastening rollers and engine pulleys.

These elements constantly experience high loads and large temperature changes. If they are not securely fastened, they can fail and cause irreversible damage to the engine.

Fixing bolts of collapsible discs

For reliable sealing of joints between composite forged discs.

Replacing wheel bolts with studs on Lada cars.

To carry out the operation of replacing the factory bolted wheel fastening with a more modern and convenient version with a stud.

(photo Drive2.ru https://www.drive2.ru/l/456906181164663095/)

That's all, good health to you and your car!

Thank you for loving ABRO!

Threaded connections are certainly convenient, but have a serious drawback. Under external mechanical influence, the fastening may be weakened, up to complete separation.

To maintain reliability, a thread locker is required. There are many mechanical devices that keep the nut (screw) from unscrewing. Read about liquid fixatives below.

A cotter pin is a rod bent in half with an eye at the bend. It is installed in the bolt hole, and the nut has special grooves for fixing. After tightening the connection, the free ends of the cotter pin are separated - the fastening is fixed.

Used on nodes that require high connection reliability. For example, a wheel nut on a car. A lock washer with fixation is placed under the nut and is secured against turning on the stationary part of the structure. The washer has a petal that bends at an angle of 90° and presses against one of the faces of the nut.

Spring type lock washer. It is one coil of spring, which is placed under the nut when tightening the connection.

The action is based on creating a thrust force. Excellent resistance to unwinding from vibration. Lock washer with teeth. On the outer diameter of the thin washer, notches are made, rotated at a certain angle.

In addition to the spacer effect, the teeth increase resistance when unwinding the thread. Nut with an oval cross-section or a plastic sleeve. Compresses the thread, increasing the force when unscrewing the bolt. Resists vibration well, but may loosen the connection under rotational load.

All these fasteners have a common drawback: they make changes to the design: replacement of standard fasteners is required, or the purchase of additional parts. How to fix a standard connection, without unnecessary components?

A simple solution - liquid threadlockers

Mechanical thread locker is not suitable for all types of connections. Quite often, when assembling a unit, it is not possible to install a third-party object into the structure.

In such cases, adhesive fasteners are used: the fixing compound itself is not able to hold the parts, but it is easy to prevent the nut (bolt) from unwinding.

Previously, varnishes and paints were used to fix threaded connections. When tightening, a drop of durable paint was simply applied to the threads, and the nut did not unscrew without applying additional force.

Video testing of threaded fasteners

However, this method was not reliable - after all, paint and varnish compositions are not intended for mechanical fastening. In addition, in the space between the threads, where air access is limited, the composition does not harden, or occurs too slowly.

Therefore, the practice of “dropping paint on the thread” has long been abandoned. Today, special adhesives or sealants are used: so-called anaerobic thread lockers.

Operating principle of anaerobic fixators

For reliable fastening, the adhesive composition must go from a liquid state of aggregation to a solid state: that is, it must polymerize. All sealants and adhesives work on this principle: while the composition is in a sealed container, it is liquid.

After application to the surface to be treated, the chemical components react with oxygen and hardening occurs. The problem with threadlockers is that the main working surface remains sealed (inside the threads).

There is no oxygen access, polymerization does not occur. What is needed for the normal completion of the reaction? This property is characteristic of anaerobic microbes that develop in conditions of limited access to oxygen.

How to fix a threaded connection and lock the nut so that it does not unscrew due to vibration? How to fix and lock a screw or bolt? Vibration resistance of threaded fastening. Vibration resistance (10+)

Fixing the threaded connection - Continued

Glue

Glue or a special fixing compound is applied to the internal and external threads in the place where they will be combined. After drying, the connection is locked. For such fixation, you can use glue that meets the following requirements: (1) It glues the material from which the bolt and nut are made (this can be steel, bronze, fluoroplastic, etc.) (2) It is quite elastic in the dried state and vibration resistant. (3) It is resistant to the environment in which it is intended to be used. For example, it is water resistant if the connection is in water. (4) It dries quickly. It should be remembered that under carving conditions, one-component adhesive rises at least four times slower than under standard conditions, so the instructions for drying time should be multiplied by four, or better yet by six for a margin. If the glue dries slowly, the work risks taking longer. For example, PVA in carvings takes a week to dry. Two-component adhesive (with hardener) cures for a nominal time.

I use the following glues and varnishes:

• Moment glue or rubber glue, if the connection will not be exposed to oils, solvents or their vapors, or sunlight.
• Any universal elastic glue "Liquid nails".
• Poxypol.
• Plumbing glue.
• Universal superglue.
• Primer GF-021 or Otex, if the connection will not be subjected to too much stress.

When choosing glue, consider the dimensions of the parts to be joined. For small parts you need liquid adhesives, such as superglue or Moment. For very quick fixation, you can use hot-melt adhesive, applying it with a hot-melt gun.

Flaws. This connection is quite difficult to disassemble. Sometimes the glue sets so much that it takes a lot of effort to unscrew it. But it is enough to provide a small initial offset. Then the process goes easily.

I like this method because it allows me to assemble threaded connections almost by hand, without tools. While the glue is not dry, it serves as an excellent lubricant and allows you to tighten without effort.

Teflon nut or insert

Inside the nut, a Teflon film is applied to the thread or part of it, or a winding is used - the external thread (bolt) is wrapped with a thin Teflon thread. Once tightened, Teflon creates increased friction and prevents vibration from loosening the connection. With the help of winding, you can fix almost any connection.

Flaws. The Teflon nut is disposable. After unscrewing, it must be replaced. The winding is also disposable. After disassembly, the remnants of the winding must be removed, and a new one must be wound before reassembly.

Common combinations

None of the options provide a 100% guarantee. Even the most reliable method - a cotter pin - can fail. The cotter pin may shear (break and fall out). Therefore, in particularly critical places, the described methods can be combined. You can put a groover between the nut and the locknut, glue a Teflon winding or nut, apply glue to the nut and locknut, etc.

For a threaded connection located in oily liquids (oil, gasoline, kerosene, diesel fuel...) and subject to vibration, only a cotter pin is suitable. All other options are unreliable. In industrial conditions, the reliability of other types of connections can still be ensured, but not in a homemade version.

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