Thread locker - types, what it is needed for. Fixing a threaded connection Assembling pneumatic system fittings
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.
The term “anaerobic” came to technology from biology. This is the name given to microbes that prefer to exist and develop in the absence of oxygen. By the way, this is why all the tubes with anaerobic compounds we purchased are sold half-empty: they need air for storage! And when it enters a limited volume without air flow (for example, into a threaded gap), the composition quickly polymerizes, that is, hardens. Such means are used not only for locking threaded connections, but also for sealing welds, sealing flanges, etc.
Why did you need a replacement for growers and other ancient remedies? The class of thread accuracy has increased, optimal tightening torques are used in production, and bolts with an increased bearing surface are used. Therefore, the old-fashioned methods have practically died out: it is almost impossible to find a grower on a modern machine. But fixing compounds are used more and more often - when attaching brake calipers, camshaft pulleys, in gearboxes, and steering mechanisms.
To test anaerobic clamps, we prepared fastening elements with M10×1.25 threads - bolts and nuts. For each test product, we took it together with a nut screwed onto it, having previously cleaned and degreased them, treated the threaded part of the bolt with a fixative, after which a second nut was screwed onto it with a small fixed tightening torque (0.1 N m). A small tightening torque value is chosen so that it does not affect the final measurement, the purpose of which is to determine the loosening torque on an untightened threaded connection. In other words, we tested exclusively the effect of the clamps, and not our own muscles. Each of the threaded connections was numbered according to the conventional number of the fastener with which it was processed.
Manufacturers declare the abilities of drugs in different ways, but color gradation is mainly used. Red color suggests that we have before us a product with the highest possible capabilities - heat-resistant and even “one-piece”. Blue color indicates more modest fixing capabilities - the connection will remain detachable. There are also very weak drugs - green.
We do not recommend focusing only on color: look for exact information about the purpose of the product either on the packaging or in the description. However, not everything is transparent here either. For example, from what moment the connection is declared “inseparable” is not clear from the descriptions. Some manufacturers indicate the moment of resistance that their product provides, but do not talk about the corresponding size of the threaded connection. And this is important, because a tiny screw from glasses requires much less torque to unscrew than a huge hub nut. There is an opinion among people that “you can assemble it with a strong latch and that’s it.” But that's not true. Strong clamps can really kill small fasteners, but no sealant will turn even medium-sized connections into a monolith, for example, those with M10...M14 threads.
That is why we decided to test all purchased drugs using a single method. After 24 hours at room temperature, each connection was clamped in turn on a stationary frame so that the head of the verified torque wrench captured only the upper nut, which had to be unscrewed. The initial torque set on the key is 5 Nm, which is less than 10% of the maximum tightening torque of such fasteners (on M10 connections in cars the torque reaches 80 Nm). If the connection could withstand the specified force, the moment was successively increased in increments of 5 Nm. The higher the moment at which the threaded connection began to unwind, the higher the quality of the fastener being tested.
The final assessment was adjusted taking into account the manufacturer’s promises: those products whose descriptions did not promise anything received a lenient assessment, while powerful “red” ones, which frankly did not live up to the stated indicators, were subjected to harsher criticism. At the same time, the viscosity of the drugs was assessed. They differ noticeably in this parameter, but we did not find a direct relationship between viscosity and professional suitability of the product.
By the way, the clamps protect against oxidation and seal the connection. And sometimes the best fixative is rust. Along with anaerobic fixatives, we decided to test other methods of stopping joints - just for comparison. About them - a little lower.
| approximate price 70 rub. The sealant, liquid as water, gave in at the first test. However, his instructions did not promise anything specific. | approximate price 190 rub. The removable American fastener removed itself at the very first step of testing - with a minimum applied force of 5 Nm. | approximate price 190 rub. The rather thin composition successfully withstood the applied torque of 5 Nm, but gave up at the next threshold - 10 Nm. The result is weak, but the vast majority of drugs failed even this. |
| approximate price 150 rub. The rather thick product promised to last until 35 Nm. It's hard to say what the manufacturers had in mind, but it didn't take more than 5 Nm to unscrew our bolts and nuts. Fail. | approximate price 150 rub. The thick sealant promised to last up to 35 Nm, but in practice it gave up at 10 Nm. Better than many, but essentially it doesn’t matter. | approximate price 150 rub. The product promised to last until 17 Nm, regardless of the thread diameter. And the recommended range of application for thread diameter is not indicated. The result is negative: the connection easily untwisted already at a modest 5 Nm. Fail. |
| approximate price 290 rub. The product of medium consistency withstood a torque of 5 Nm, but gave up at the second step. Well, most couldn't do that either. | approximate price 390 rub. The rather fluid product did not show itself in any way, allowing the nut to unscrew on the first try. But there were no specific promises. | approximate price 310 rub. An expensive American product of modest volume showed nothing but ambition. The medium fluidity fastener gave in at the first contact with the torque wrench. What about the definition of “high-strength”? Failure! |
| approximate price 105 rub. The Russian product is a substance of medium viscosity. The tests ended very quickly: an applied torque of 5 Nm instantly moved the nut out of place. However, the manufacturer did not make any specific promises. | approximate price 105 rub. In practice, the rather thick composition behaved just as poorly as its colleague number 10: on the first try, the nut easily came loose. And this is called “one-piece”? Fail. | approximate price 190 rub. Not the thickest product, prone to dripping, won the competition by a large margin over its competitors! It was possible to move the nut fixed by him only by applying a torque of 30 Nm. Great! |
| approximate price 190 rub. The thin crew refused to fulfill their duties, giving up at the very first stage of inspection. We will assume that this means “medium strength”. | approximate price 160 rub. How to understand the contradictory wording “up to 20 mm or more”? For any thread? It sounds optimistic, and the torque is promised to be at least 35 Nm. But there was no result - the product of heterogeneous consistency gave up on the first step, at the mere sight of the key. Fail. | approximate price 160 rub. The product promised to fix fasteners up to a torque of 35 Nm, but things didn’t work out from the very beginning. The bottle with the screw cap leaked immediately - sealed products are better! The liquid of medium consistency, after the required exposure, gave up at the first touch of the key. Fail. |
| approximate price 160 rub. The thin product declared its readiness to last up to 17 Nm. It didn’t work: the connection came loose at a torque of less than 10 Nm. Our rating: satisfactory. | approximate price 300 rub. This product is not designed for a thread diameter of 10 mm, but we wanted to try it - what if? However, no “suddenly” happened: the nut came loose on the first try. But we won’t find fault: the product is stated to be weak. | approximate price 285 rub. The thick product loosened its grip only at a torque of 25 Nm. This is the second result in our sample. Very good! |
| approximate price 225 rub. During testing, the rather thick American product gave up almost instantly - already at a torque of 5 Nm. But the drug did not promise anything special. | approximate price 220 rub. The sealant of medium thickness gave way at a minimum moment. And why was it necessary to announce high durability? Fail. | approximate price 260 rub. In terms of fluidity, this product is identical to water. And the effect is the same as water. On the first try, the nut immediately moved out of place. But the manufacturer didn’t say anything special. |
Who recorded who?
Well what can I say? The overall impression is quite pathetic. Of the twenty-one drugs tested, only six were able to withstand a modest initial torque of 5 Nm, and only two of the remaining ones advanced beyond 10 Nm.
However, the Teflon nut and lock washer also failed at the first stage. And nail polish turned out to be unsuitable for serious matters. The extra-grade glue left over from previous examinations lasted a little longer - it gave in under a load of 10 Nm. And the most curious thing is that at a torque of 30 Nm... the cotter pin was cut off! It would seem that the metal part would last longer, but it only repeated the results of the best drug we tested.
Often it is necessary to tighten a bolt or screw so that it does not unwind, at least on its own, under the influence of the environment. The subject of this review is intended to solve this problem. Below the cut is a review and test drive of an anaerobic gel for fixation.
When I wrote about anaerobic sealant, there were many questions in the comments about its capabilities for fixing threads. I replied that there are other products for this, and we will consider one of them. In conditions of a consistently unstable exchange rate, Russian-made products often turn out to be more interesting than their foreign counterparts.
When I ordered pipe sealants, I also added this fixative to the cart. Delivery from the manufacturer is paid up to a certain amount (500 rubles - 6.5 $), so it makes sense to get goods up to this amount. Now I got around to dealing with this product. The parcel arrived in about a week and a half, the manager of the transport company called and arranged delivery. The main product there was, of course, which caused a great response among readers. I ordered the thread locker as an extra.
Here is what the manufacturer writes about this clamp (I have summarized a little information from different places on the manufacturer’s website):
- replaces lock washers, securely fixes bolts over M20;
- can be used in joints from -0.2 to +0.6 mm, to fill microdefects in welds, castings, rolled products, pressed materials;
- sealing immediately after application (final polymerization occurs after 15-30 minutes - the product blocks the part);
- no strong tightening required during assembly;
- resistance to abrasion, high mechanical loads, and temperature changes;
- protection against corrosion due to high adhesion to metal;
- resistant to organic solvents;
- does not creep, does not shrink, increases structural strength;
- operating temperature range from -60 to +150 °C;
- dismantled with heating up to +150 ºC;
- protects threads from corrosion.
Well, let's check its properties. In general, it is very important to fix the threads, especially in moving parts. The thread locker helped me a lot to ensure the stability of the connections in the automated greenhouse design that I described.
The thread locker is packaged in a blister: 
It should be noted that they are available in 4 types: with easy-to-disassemble fixation, durable, for large threads and high-strength. We have the light version in our hands: with easy-to-disassemble fixation. On the reverse side instructions for use: 
Weight with packaging 27 g: 
The tube can be removed very easily, the weight of the tube is 14g: 
Tube length is about 12 cm: 
The cap on the tube is fixed with a thread; inside there is a bluish gel: 
The tip of the tube is thin, which, combined with pressing on the tube, makes it easy to dispense the dispensed gel.
I’ll write down the features of these gels right away to avoid unnecessary questions. Gels are anaerobic - that is, they harden without air. In narrow places, in particular, at the point of contact between a nut and a bolt, or a self-tapping screw and a twisted surface, the amount of air is minimal - that’s where this gel polymerizes. The remaining gel on the outside does not harden and should be removed with a cloth.
For tests, let's take a few bolts and nuts. The seller claims to work even on M20 thread bolts, but the maximum I had was M10: 
The candidates lined up are: 
Lubricate 3-4 turns on each bolt: 
From a large bolt, part of the gel flows onto a piece of paper; it is quite liquid, so it is probably better not to place it horizontally after lubricating it. We collect the compounds and wait for polymerization for 30 minutes: 
On the left side of the piece of paper is a puddle left by a large bolt.
While the polymerization process is underway, I decided to assemble another structure. After the last one, they wrote in the comments about the vibration test. This time we can’t do a pressure test, but I think we can get vibration. What could be better suited for such tests than a children's metal construction set? I didn't find anything better and borrowed the following from the child: 
Inside, as you would expect, there are structural elements and screws with nuts: 
We will not assemble an airplane or a tractor, we will assemble a simple spear like this, using a simple tool from the construction set (the screwdriver fits into the screw slot with great force, uncharacteristic for children of the age indicated on the construction set - we will leave this to the conscience of the manufacturer): 
At the same time, the right part, marked with a blue marker, was twisted using our thread locker. I note that I tightened the screws with the same force, without fanaticism, but so that it would hold. Let's leave the simple design to dry.
In the meantime, the moment of truth has come for our bolts, we try to unscrew them (30 minutes have passed). I was unable to turn the nuts by hand, but with the help of an adjustable wrench, the screwed nuts began to move with medium force. If you need to assemble a non-dismountable connection, you should resort to versions with strong and high-strength fixation. The polymerized sealant looks like this: 
Now let's move on to our constructor. To create vibration, I decided to use a compressor that survives the winter on the balcony: 
We fix our structure with clothespins, we don’t need strength, rather the opposite - the more it dangles, the better: 
We turn it on and see how the structure vibrates. After 5 minutes of work, the structure changed its original appearance: 
We can conclude that the thread locker helps to cope with the self-unscrewing of bolts and screws.
In general, we can say that the thread locker copes with its task; no problems arose when using it. Threaded connections fixed with this gel did not cause any problems. So I can recommend it.
For dessert, the vibration video, unfortunately, did not wait for the collapse of the half without sealant:
Thanks to everyone who read to the end, I hope someone finds this information useful. I'm planning to buy +83 Add to favorites I liked the review +72 +135 Author: elremont from 06/26/2015
* nut/bolt clamps *
The fixation of the nut is very important in some cases. So I'll list you a few fixation methods and show you exactly how they are used. This is not a complete guide, there may be more methods, but these are most of the methods that I am aware of.
*Lock-nut*
The basic way to secure a standard nut is to thread the nut onto the bolt and then tighten it to the specified torque using a torque wrench, but for this demonstration we'll just hand tighten it and you could use a counter nut.
That is, the locknut is designed to secure the nut and stop it from moving. After you tighten the first nut, the second nut, or lock nut, will be placed behind the first one, and then we will tighten it. This will stop the nut from coming loose. In extreme cases, with high vibration, this type of nut can actually become loose. This happens quite often when using two regular nuts, although you can buy a specially designed lock nut like this one made specifically for this purpose.
* thread fixing compound *
You can use a thread locking compound. It is a highly fluid anaerobic fluid. Since it displaces the air around it, it is actually used as an adhesive. You simply apply it to the threads where you want them to be secured. Then you tighten the nut... Tighten it and then wait for it to dry, this will compress the nut and stop it from moving. Thread locking compound is one of the most common ways to secure a nut or bolt. This is a very effective way. There are quite a few different brands of compound available, so you need to make sure it's the right one for you. Some are so strong that you may need an impact wrench to remove them. Loctite is a very common brand. I'm sure most people have seen it. So this is a quick and easy way to secure the nut.
*Spring washers*
There are also spring washers, they are made of spring steel, and they are designed so that when you tighten the nut, there is a constant load on it, which can prevent it from unscrewing. Typically a spring washer is used along with a regular washer. First install the regular one, and then the spring one. They don’t always use a regular washer when using a spring washer; it depends on the specific location. After this, attach the nut and tighten it to the specified torque. This is a very common way to secure threads, but in extreme cases, with high vibration, the connection can become loose. I've seen this, the spring washer broke into several pieces, which meant that the nut could now be unscrewed. But in most cases, such a washer puts pressure on the nut, which makes it difficult to unscrew it. So once everything is tightened, it is difficult to unscrew it. And this will work, but it is not ideal if there is strong vibration, vibration weakens this connection.
*Toothed washers*
Serrated washers can be used to prevent some nuts and bolts from coming loose, but they are not ideal either. The problem is that if you tighten them too much, it can flatten the teeth and they will eventually just turn into regular washers. Once they are flat they are pretty much useless. But you can use them in certain circumstances, they are very popular in washing machines because they are very cheap. So you simply throw on the washer, tighten the nut, and tighten it to the specified torque using a torque wrench. It's important not to overtighten them so as not to flatten the washer, otherwise you'll end up with something like this. Like I said, it's very cheap, so they're used in a lot of washing machines and the like. They can prevent nuts and bolts from coming loose, but this is a local solution.
*Self-locking nut*
The self-locking nut has a nylon ring at the top that grips the bolt as you tighten it. That is, you can start to tighten quite easily, just like a regular nut, but once you reach nylon, then it becomes difficult to tighten, you will need a tool in order to screw the nut onto the bolt. This can take quite a long time, because you will need to turn the wrench all the way, with a regular nut you can just screw it down quite easily by hand. So self-locking nuts are very useful, they are used in many places, but they take a lot of time to turn. Self-locking nuts are useful and you will find them on all machines, but they are not very suitable for critical machinery as they can be loosened by vibration.
*Deformed node*
Sometimes you won't see a nut with warped threads on the inside, it's actually only slightly warped, so it's pretty easy to get it on initially until you get to the warped spot, and then it grips really tight. You will then need a wrench or socket to be able to tighten the nut. Once tightened, everything holds up very well, but in extreme conditions, again with high vibration, they can become loose.
*Nord washers*
They are unique in that they have cams on the face of the washers. They should be placed in pairs, like this. That is, you put two things together with the cams facing out and tighten the bolt on them. You can put a nut. Tighten to the specified torque. Once the nut is tightened, the two washers will lock onto each other and the joint will be very difficult to remove. They are very good at vibration. It is very unlikely that any of these washers, if positioned correctly, will become loose due to vibration.
* Castle nut *
They are often used in critical machinery such as aircraft. On board the aircraft, after it is tightened, a piece of wire will be threaded through it, and this will prevent the nut from ever unscrewing. So, to use one of these, you thread it onto the bolt, tighten it to the specified torque or as long as it stretches. Now I'll drill through the bolt with a small drill bit. But such a drill will work better for larger nuts and bolts than this one. It's stainless steel, so I'll work carefully and slowly. I'll put a little more lube on the drill bit. Once you've done that, you can insert the pin and bend it around and it will keep the nut from coming off until you pull the pin out.
I hope this demo was helpful to you. I've outlined some of the methods you can use to stop nuts and bolts from loosening on their own. There are also spacers for washers, which I don't have, but it's a regular washer and tab that bends and prevents the nut or bolt from coming loose.
_
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.
We also recommend
How to fix an electric kettle at home Why the electric kettle does not turn on - working stand
Restoration of wooden boxes How to decorate with carvings
How to make a plasterboard ceiling with lighting Installation of two-level ceiling lighting with LED strip
Ceiling lighting with LED strip: advantages, choice by degree of illumination, type of LED, color and density, installation and connection How to make an LED ceiling
Several options for using old CD blanks in everyday life
What is the service life of a washing machine
Loading...