How to weld a cast iron manifold at home
One of the components of the internal combustion engine is the exhaust manifold. It wears out during use. This is typical for a car with any mileage. There are many reasons for the formation of cracks: from manufacturing defects, incorrect assembly to dynamic destruction. If a part fails, do not rush to replace the spare part.
Many car repair shops specialize in welding exhaust manifolds. Having a welding machine in the garage, you can restore the part yourself. This can be done in several ways. The collector is made of stainless pipes or cast iron. Both alloys can be welded, but each technology has its own nuances.
Experts are ready to share their experience.
Exhaust manifold: causes of failure and maintenance
Depending on the make of the car and the type of engine, models of various modifications are installed on the engine. They can be divided into two groups:
- all-metal, they are usually made by casting iron;
- tubular, for their production stainless pipes of various diameters are used.
The manifolds are attached to the internal combustion engine block using flanges. At each stroke, exhaust gases enter the chamber under pressure. Their temperature reaches 900 degrees. It is clear that a part operating in this mode can break.
A leak in the exhaust manifold is the most difficult defect. Possible situations:
- one of the pipes burns out;
- cracks appear on the collector due to dynamic load;
- The pipe breaks off completely.
All this damage is a problem. For many cars, the procedure for replacing a part drags on for months - “original” spare parts sometimes have to be ordered.
Many service stations restore them. Welding of collectors, depending on their modification, is carried out using hot, cold or argon welding methods. The work is carried out using different types of equipment, using electrodes or filler wire. Restoration can be done in the courtyard or garage. How to weld the exhaust manifold yourself? Let's consider each of the methods in detail.
Welding a cast iron exhaust manifold
Temperature processing of a high-carbon alloy is associated with certain difficulties:
- carbon burns out when exposed to heat, the metal becomes friable;
- Cast iron has a high fluidity coefficient;
- upon rapid cooling, due to internal stress, the casting begins to crack and becomes whitish, this indicates a change in the structure of the alloy.
Welding a cast iron exhaust manifold can be done by trainees. It is better for beginners not to undertake the restoration of a car engine part, or they should first practice on junk cast iron products.
Until recently, welders did not undertake repairs to cast iron. The seam turned out to have a high content of scale, and the metal cracked in the heating zone.
After the advent of special copper-containing electrodes, which made it possible to reduce the temperature in the melt bath to +120°C, it became possible to create strong connections.
Hot and semi-hot methods are not fundamentally different. The crack is welded with copper-containing additives when the part is preheated. When hot, the part is heated in the oven to a temperature of +600°C, a crimson tint appears. It is noticeable when shaded.
After this, welding begins. To prevent the part from cooling down quickly, it is periodically heated with a blowtorch. With the semi-hot method, the part is heated within +300°C. The result is an even seam. It is very important to maintain the temperature during cooling.
If the crack depth is large, it:
- pre-cut to the full depth;
- the edges are drilled out on both sides;
- the edges are smoothed at an angle of 30°.
They make a multilayer connection. Each seam must be forged, the penetration length is no more than 3 cm. The seams are made perpendicular to ensure a reliable connection. For electric arc welding, electrodes of the TsCh-4 brand are used.
The cold method does not require preliminary preparation. The crack is fused at temperatures up to 200°C. For work, special electrodes OZCH-6, OZCH-2 are used.
The fracture strength of a cold joint is lower. For critical connections (when the outlet manifold pipe is completely broken off), it is better to take MNCh-2 electrodes. When semi-automatic gas welding, copper filler wire is used.
Welding a stainless steel manifold
Tubular components usually burn out at bends. Difficulties of working with stainless steel:
- alloyed alloys in the working area are subject to temperature deformation;
- Nickel, chromium, and other components actively oxidize when heated, which has a detrimental effect on the quality of the weld.
To eliminate defects, the argon welding method is used. The protective atmosphere protects the metal from oxidation; due to the airflow, the area bordering the working area heats up less.
It must be taken into account that the thermal conductivity of stainless steel is lower than that of black low-carbon alloys. A small operating current is needed; it is selected experimentally. It is important to observe the speed of seam formation.
The metal is welded in large passes so that intercrystalline corrosion does not occur in the joint area. The operating mode depends on the equipment used.
Possible methods:
- using a universal inverter, refractory tungsten electrodes are used for argon welding in CD/AC TIG mode;
- for manual electric arc welding, heat-resistant MMA additives with a rutile coating are needed;
- for semi-automatic machines, stainless steel wire is chosen; the seam is dense and does not require additional processing.
Cold welding when repairing the exhaust manifold
Small defects are repaired using special adhesives called “cold welding”. Before applying the mixture, the area to be repaired must be degreased. Adhesives should be used strictly according to the instructions. Then the result is a patch whose physical properties are similar to metal.
This method is convenient for eliminating cracks and burnouts in hard-to-reach places. Glue is only a temporary measure to fix the damage. Under heavy loads of hot gases leaving the cylinders, the patched components will not last long. The adhesive composition is not designed for dynamic loads, but it can withstand static loads very well.
Before purchasing glue, it is important to study its characteristics.
Conclusion
If the engine malfunctions, be sure to check the integrity of the output manifold. This is the most vulnerable part, operated in an aggressive environment under high pressure. If a defect is detected, evaluate whether you can repair the part yourself. Without experience, it is better not to take on such important work; entrust the restoration to a specialist.
Source: https://strinstrumenty.com/uslovie/kak-zavarit-chugunnyj-kollektor-v-domashnih-usloviyah.html
Welding exhaust manifolds
The exhaust manifold is an important and necessary part of the internal combustion engine of a car, which is mainly made of cast iron. Moreover, its location leads to the fact that working conditions can be called rather extreme.
This is a huge temperature difference, as a result of which condensation appears on the inner walls of its pipes, and the passage of exhaust gases, and resonating exhaust waves - all this does not have the best effect on its condition and the durability of the collector.
Condensation leads to corrosion, and this in turn leads to the destruction of the metal.
An exhaust manifold
Collectors can be either solid, made of cast iron using casting, or tubular, welded from steel pipes and parts.
Tubular exhaust manifold
Tubular ones are also distinguished by the type of connection of these pipes, as well as by their length and, as follows from this, volume. Naturally, the larger the volume, the better, and the more expensive the collector. For example, sports cars are equipped with manifolds with long pipes of the same length and complex weaves.
If you hear unusual sounds when idling that are not related to the operation of the engine, or the engine itself has become unstable or fuel consumption has increased, then you need to check the condition of the manifold.
This can be either the destruction of the mounting eye or gasket, which is installed between the cylinder block and the manifold itself, or a change in the geometry of the connecting flanges under the influence of high temperatures. There may be a simple breakage of the studs, or there may be a problem such as the appearance of a crack in the housing. Depending on the extent of the damage, the exhaust manifold is repaired by welding or, if things are really bad, it is replaced.
The most commonly replaced exhaust manifold gasket
Corrosion and carbon deposits can cause a pipe to become clogged, which requires a solution.
Of course, the easiest way is to go to a service station, but some repairs can be done yourself, and not only by a super experienced specialist.
To do this, you need to wait until the engine and the collector itself have cooled down to the temperature at which you can work with them, after which we begin to disassemble, starting with the engine casing, the collector, and other things that may interfere. We remove the collector assembly itself by unscrewing the fasteners. We change the gasket, if necessary, or another part, and install everything back in the reverse order.
Welding a cast iron exhaust manifold
If a crack is found in the collector, it is welded. The welding method depends on the material from which it is made. If it is cast iron, it differs from other alloys with iron in that during melting its carbon content increases, from 2 to 6%, which distinguishes it from other ferrous metals.
Weld seam on a cast iron manifold
Welding cast iron requires the welder to have certain qualifications. It was previously believed that cast iron, due to its fragility, cannot be welded at all, but now, using special electrodes and working out the method of preheating the part, the weld is of good quality and with the necessary properties.
As mentioned, we heat the part immediately before welding and try to maintain the temperature during the entire welding process. Cast iron tends to cool quickly.
Since molten cast iron has increased fluidity, you can either drill holes along the crack or use graphite spacers under the crack. It is also necessary to clean the welding area well.
In addition, during welding, carbon burns out with the formation of CO, which leads to pore formation. And this also affects the quality of the seam.
After the work is completed, it is necessary to ensure that the parts are gradually cooled slowly in order to prevent the appearance of new cracks in the area of the weld and the appearance of a layer of “white cast iron”, which is absolutely not processed in any way.
Welding of a cast iron exhaust manifold can be done either hot or cold. Each method has its own types of electrodes. For example, for hot welding they use grade TsCh-4, for cold welding it is better to use OZCh - 6, OZCh - 2. The latter are more suitable for the collector, since the former are better used for welding products with thin walls. It is also good to use MNC-2 electrodes, which are used for critical products.
Types of cast iron welding, in our case both types are used
For welding with these electrodes, reverse polarity current is used.
With the hot method, the entire part is heated to a temperature of 200 to 600 degrees, no more.
Gas welding gives very good quality results, which protects cast iron from carbon burnout and makes it possible to heat the part.
Cold welding for the exhaust manifold is a technology in which the seams are welded in short sections, in several layers.
Technology for filling seams when welding cast iron
It is used when it is not possible to heat the product; in this case, OZCh -2 electrodes are used, which have a copper core coated with a special layer and MNC -2, with a core of copper, nickel, iron and manganese.
Certainly. The first option is more accessible. The arc during the welding process is short. Make seam sections from 3 to 5 cm long, taking a short break so that the seam cools down, but to about 50 degrees, then it needs to be lightly hammered.
This prevents the formation of cracks.
Welding a stainless steel exhaust manifold
Stainless steel exhaust manifolds are also repaired by welding, and here too the work has its own characteristics. Since this is steel in an alloy with nickel or chromium and other additives, during the welding process in the weld area these elements can burn out, so they need to be welded in a protective gas environment.
In addition, metal deformation to varying degrees is possible during welding work.
If the process is carried out according to technology, the collector practically does not require subsequent processing of the flange. It is imperative to calculate the current strength; it should be low, since the thermal conductivity of this steel is much lower than ordinary steel with a low carbon content and additives.
The process of welding stainless pipes with argon
If the welding mode is not followed, the weld is obtained with less anti-corrosion properties than the base metal. This is achieved due to the fact that the arc heats the metal to a temperature above 500 degrees, and a redistribution of chromium and iron molecules occurs. This process is called intercrystalline corrosion.
The most common types of stainless steel welding are:
- welding with tungsten electrodes in argon with a universal inverter, for example, DC/AC TIG;
- welding, mostly manual, using electrodes coated with a special compound;
- semi-automatic, with argon environment, stainless wire is used as an electrode;
- cold, under pressure, but it is not used for welding collectors.
For welding at home, that is, in the garage, welding using specially coated electrodes (MMA) is used.
For these works, we select electrodes of two types: with a base made of titanium dioxide and coated with rutile and coated with magnesium and calcium carbonate.
The former are used for welding with alternating current, the latter with direct current. It is better to choose the thickness of the electrode according to GOST 10052.
If you are not a professional welder, excellent quality of the weld is not guaranteed, although you can and should strive for it.
Basically, welding work is best done in specialized workshops where there are different types of equipment. Good equipment, the correct mode and an experienced technician and your collector will be like new.
Real professionals will not only repair the exhaust manifold, but can modify it or make a new one.
DIY manifold
Repair of exhaust manifold by cold welding
Cold welding has become quite widespread among home craftsmen who know how to apply this method correctly.
Adhesive Cold welding for joining metals
If you follow the instructions exactly, you can join metal parts very well. Naturally, this is not a real cold welding method, which is performed by pressing two elements before plastic deformation of the joined edges of the parts begins.
In our case we are talking about a special adhesive composition. When applying the composition to the place where metals are joined, we end up with a seam that has the properties of the metals being joined.
Application of cold welding for repair of metal products
Cold welding is used in cases where it is impossible to use traditional methods, for example, parts can be deformed during the welding process, the shape of the parts has complex geometry, and the parts being connected consist of different metals.
In this case, the connection is very strong and of high quality, and can withstand heavy loads for a long time.
But is it possible to seal the exhaust manifold using cold welding? This is a very interesting question. Yes, car parts, including cracks in the exhaust pipe, are perfectly connected using this composition, but loads and a large temperature difference in the manifold call into question the feasibility of its use.
Although it can be used as a temporary measure. There are reviews that when using this glue, the car has already covered 800 km, others advise not to take risks, since the seam does not work against shear or torsion.
Cold welding, according to the manufacturer, also repairs manifolds
Perhaps it has to do with the correct use of the glue and its quality, that is, the manufacturer.
Source: http://themechanic.ru/svarka-vypusknyh-kollektorov/
Welding a cast iron exhaust manifold
The exhaust manifold is one of the most important components of your vehicle. The simplest manifold consists of several pipes welded together into a single system through which exhaust gases are discharged. Every car has an exhaust manifold, regardless of its price or year of manufacture.
Since this is one of the most important components, it has to withstand enormous loads. Under such conditions, the collector is not able to operate properly and cracks and sometimes through holes form on it.
Especially if the car is old and maintenance has not been carried out often. In such situations, welding of the collector is necessary. With its help, you can repair the unit and not have to purchase a new one.
In this article we will tell you everything you need to know about welding exhaust manifolds.
general information
Regardless of the vehicle, it can be equipped with a tubular or solid manifold. The one-piece unit is cast from cast iron and has no seams. It is the most durable and durable. Tubular is made by welding several pipes into a single system. This option is less reliable, but more repairable, since it is often the seams that burst and can be re-fused without any problems.
The collectors themselves are made of cast iron, heat-resistant steel or aluminum. The unit is cooled using air, but sometimes this is not enough. In critical situations, the collector becomes severely overheated or overcooled, seams burst, cracks or other visible defects form.
Cracks can be caused by engine malfunctions, improper operation of the catalyst, careless driving through puddles and slush, improper engine washing, aggressive driving, and much more. Sometimes frequent breakdowns are associated with manufacturing defects or the manufacturer’s desire to shorten the life of the car.
Modern automakers do not prioritize the quality of their cars, often making components from low-quality metal or making mistakes during assembly.
Welding of the collector is necessary if the cracks have reached a length of 5 centimeters or more, if fragments of the collector have burned out, the collector itself has split into several components, or the seams have burst.
Exhaust manifold repair
Many car enthusiasts panic when they see that the seams of the exhaust manifold have burst or it has completely split in half. If your unit is no more than 10 years old, then do not rush to buy a new one to replace a faulty manifold. It can be easily repaired if you have welding skills.
The collector is welded in a ventilated (but draft-free) garage using electrodes. You can also weld the crack with argon or weld the cast iron with gas-powder surfacing. If you do not have sufficient skills, then it is better not to take this job. And we will further tell all experienced craftsmen about the nuances of repairs.
First of all, you need to drill out the edges of cracks or burst seams. Cut the edges along the entire depth, just do not use a standard grinder for this.
Now the crack can be welded using the argon arc welding method, or fused with gas powder surfacing. Sometimes there are collectors that are so burnt out that even the most experienced welder cannot repair them.
So evaluate your strengths and think: might it be better to spend money on a new unit?
After welding, allow the manifold to cool. If possible, it is better to use a welding jig. After welding, be sure to sand the surface of the commutator. It is extremely important to restore all planes of the unit after repair, otherwise the seams are guaranteed to burst again and the cracks will spread. There is no point in making repairs if the manifold does not have a gasket. And be sure to control the geometry of the holes.
For an experienced welder, repairing one aluminum, cast iron or steel exhaust manifold takes an average of 2-5 hours, depending on the nature of the breakdown and working conditions. This is subject to welding with argon or electrodes. If you use the gas-powder surfacing method, the repair may take several days, since the collector needs at least a day to cool down.
Instead of a conclusion
Remember that non-compliance with welding technology, violation of safety regulations and the desire to quickly complete repairs of the exhaust manifold can lead to disastrous consequences. The work of some welders is sometimes impossible to redo due to the huge number of errors, and such a collector is automatically sent to a landfill.
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Source: https://varimtutru.com/svarka-vypusknogo-kollektora-iz-chuguna/
Exhaust manifold repair and welding
Repair of the exhaust manifold may be necessary due to the appearance of a crack in it. This phenomenon is quite common, since this part is subject to a number of negative influences both from the inside and from the outside:
- In contact with the engine, the collector is subject to temperature changes and withstands engine vibration;
- By removing exhaust gases, it is exposed to thermal effects, since their temperature often reaches several hundred degrees Celsius;
- Stopping the engine leads to rapid cooling and condensation.
All this leads to the emergence and development of corrosion processes, which ultimately cause the appearance of a crack. Timely welding of the exhaust manifold will not only avoid the need for an expensive replacement, but will also eliminate the possibility of an unexpected breakdown and stop of the vehicle.
Where to contact?
Repairing the exhaust manifold by cold welding does not achieve good results. Therefore, the specialists of “M.B.S.” It is recommended to carry out argon-arc welding at a professional level. Only it is capable of ensuring the connection of metals at the chemical level, and therefore the highest strength of the seams.
Our specialists have extensive experience and successfully solve problems even of increased complexity. welding of a cast iron exhaust manifold from us , which not every welder can undertake. This type of work requires knowledge of a number of subtleties: for example, the need to heat a part to a certain temperature.
If necessary, you can always contact us and order exhaust system repair services.
How is the exhaust manifold repaired?
Finding signs such as:
- unpleasant smell in the cabin,
- strange sounds when the engine is running,
- malfunctions of electronic engine control systems,
- drop in turbocharger boost pressure,
- contact us! Our specialists will conduct diagnostics and determine whether the exhaust manifold of your car can be restored. If possible, a specification will be drawn up and agreed upon with the customer.
Only after this our specialists will begin work:
- if there are cracks, they will be welded;
- if there are broken fragments, they will weld them;
- if the collector is split in half, the parts will be welded together;
- if burnt parts are detected, they will perform surfacing, which will thicken the walls.
Do you need a high-quality and inexpensive exhaust manifold repair? Contact M.B.S.!
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https://mbsfs.ru/argon-welding/exhaust-manifoldWelding a cast iron exhaust manifold with your own hands in the garage
A similar manifold is designed to remove exhaust gases from an internal combustion engine (ICE) and is one of the important systems in any car. During operation of the internal combustion engine, it is subjected not only to high temperature loads, but also to vibration, which is why cracks form. Welding exhaust manifolds is a complex matter; it requires an experienced performer who knows how to work with cast iron.
Main causes of breakdowns
In the exhaust system, especially of an old car with a lot of mileage, problems arise that are independent of the muffler material, so every driver should periodically inspect the entire system for cracks or burnouts. Timely maintenance will save the car owner from problems with replacing the exhaust manifold , which is very expensive.
The safety of the exhaust gas exhaust system is affected by:
- exhaust gases having a high temperature;
- aggressive mixtures;
- vulnerability of the metal under high loads during operation.
The problems that arise are divided according to the design elements of the exhaust system:
- The particulate filter (catalyst) serves to retain the soot contained in the exhaust gases, so the honeycomb segments become heavily clogged, and due to high temperatures the segments melt. Signs of problems - gases practically do not come out of the exhaust pipe or acrid bluish smoke appears.
- Oxygen sensors - the housing is depressurized or overheated, wear and tear occurs, there is no contact in the electrical circuit of the machine, mechanical damage has occurred.
- The corrugation in the muffler is a cylinder, inside of which there is a corrugated tube protected by a double braid, the top layer of which is made of stainless steel. The housing is elastic, therefore it dampens negative vibrations and prevents destruction of the entire system - rupture occurs due to a sharp increase in gas pressure when the catalyst is clogged.
- The resonator is installed in front of the main muffler, so many car enthusiasts call it a small or additional similar element of the exhaust system. If the volume of gases escaping or vibrating sounds at the installation site of the resonator has increased, this indicates that one of the internal components of the product has burned out.
- The muffler indicates that it needs to be repaired or urgently replaced by loud sounds when the internal combustion engine is running or a sharp drop in engine power, as well as strong vibration at the mounting location.
- Exhaust manifold , if you smell exhaust gases in the cabin, it means that a crack has appeared on its body or the pipe has ruptured.
Equipment and materials
To weld a cast iron collector, it is better to use an inverter and a cold method , as it is most suitable for home conditions. The guarantee of success is the following components: welding mode and choice of electrodes, and you need to use special products containing nickel or copper.
Domestic manufacturers offer the following brands for this type of work:
- OZCh-2 and OZCh-6 , where the base is a copper rod, which is covered with coating, where iron powder is present;
- iron-nickel electrodes for DC welding;
- Copper-iron-nickel MNC-2 allows you to obtain a high-tech type of seam joint that prevents the formation of corrosion and perfectly withstands contact with aggressive environments and hot gases.
Features of the work
If a crack is found on the manifold, then you need to weld it immediately, without waiting for it to lead to a break in the pipe . In this case, it is necessary to take into account what material the product is made of, for example, cast iron differs from other materials in that during welding work it is necessary to increase the presence of carbon within 2-6%.
Seam connection
Welding a cast iron manifold requires high qualifications from the performer; it is carried out with heating of the part or using a cold method, for each it is necessary to select the appropriate electrodes.
When heating, it is necessary to constantly maintain the temperature of the product, since cast iron cools quickly . It is necessary to drill holes on both sides of the crack to prevent it from spreading when heated.
Thoroughly cut the crack so that the new metal fills it completely, and clean the adjacent area. The welding process is accompanied by a large release of CO2, as carbon burns out, so it is necessary to organize a powerful exhaust hood. Excessive vaporization deteriorates the quality of the seam. After welding is completed, heating of the part continues so that the cast iron cools slowly and a layer of white coating cannot form on the surface of the weld, which cannot be processed.
Types of cast iron welding
In industry, there are three methods of welding cast iron:
- Hot - the workpiece is heated to 600-650 °C.
- Semi-hot , when the metal heats up no higher than 300-350 °C.
- Cold option - the part is not heated.
The third option differs in that the seam is welded in short sections, followed by a second layer to avoid warping.
Gas
Gas welding of cast iron parts gives good results in terms of quality and strength of the seam , while excessive carbon burnout is prevented, and the technique also allows for preliminary and subsequent heating of the product for slow cooling.
Using a semi-automatic machine
The technique is simple, the main thing for the performer is to know the welding procedure and prepare the part in advance; the strength and quality of the seam joint depends on the second action. Wire of a special composition is used as an additive.
Argon
Using argon as a shielding gas when welding semi-automatically is quite expensive; the best option is TIG welding of cast iron structures using a non-consumable tungsten electrode in a shielding gas environment.
Using an inverter
Similar welding requires a large amount of preliminary work, taking into account the following recommendations:
- the welding area is cleaned to a shine with a flap wheel;
- then thoroughly degrease the surface with B-70 gasoline or another solvent;
- deepen the crack by making a cone-shaped joint.
With an inverter, welding is performed layer by layer, and steel studs are used as supporting elements.
DIY repair
A cast iron exhaust manifold can be repaired by welding in your own garage if you have the skills to similarly process this metal and the necessary equipment. First, the edges of the cracks are drilled, retreating from 3-5 mm, the edges are cut to the full depth; only experienced performers advise not to use a grinder.
After preparation, they begin welding using argon-arc equipment, or deposit metal using the gas-powder method . After welding work, if there is a special manipulator table on which it is convenient to securely fasten structures in the desired position, the product is given time to cool. The resulting seam joints must be sanded.
Repairing a manifold made of cast iron or stainless steel takes an experienced contractor at least 2-5 hours, which depends on the nature of the malfunction and the conditions of the work. For example, welding with electrodes or the gas version is included in this period of time, and the powder surfacing technique requires several days, because the collector will cool for at least a day.
conclusions
Before you begin repairing a cracked exhaust manifold, you need to realistically assess your strengths; keep in mind that the slightest deviation from the welding procedure, violation of safety regulations and the desire to finish the work quickly will lead to negative consequences. Even a professional cannot redo the welding of a would-be master, since serious mistakes were made - it is easier to send such a product to a landfill, and in return buy a new one from the store.
Source:
https://svarka.guru/tehnika/detaley/vypusknogo-chugunnogo-kollektora.htmlWelding exhaust manifolds with your own hands
The exhaust manifold is one of the most important components of your vehicle. The simplest manifold consists of several pipes welded together into a single system through which exhaust gases are discharged. Every car has an exhaust manifold, regardless of its price or year of manufacture.
Since this is one of the most important components, it has to withstand enormous loads. Under such conditions, the collector is not able to operate properly and cracks and sometimes through holes form on it. Especially if the car is old and maintenance has not been carried out often. In such situations, welding of the collector is necessary. With its help, you can repair the unit and not have to purchase a new one. In this article we will tell you everything you need to know about welding exhaust manifolds.
Can the exhaust manifold be cold welded?
Cracks, chips, corrosion are the most common problems with exhaust system elements. They cannot be ignored, and replacing the exhaust manifold requires significant costs. One option is to restore the part using welding, but this is a difficult task and not everyone can do it on their own. There is an alternative solution - cold welding. But is it possible to cover the exhaust manifold with cold welding and thereby eliminate the defects?
What is cold welding?
This is a two-part adhesive based on epoxy resin and hardener. The hardener contains metal dust, which makes the joint more durable, reinforcing it, and increases resistance to high temperatures and mechanical stress. The glue is impervious to chemicals, moisture, and temperature changes.
The sealant can withstand thermal loads from 200 to 1400 degrees. Moreover, by increasing the temperature during polymerization, the mixture can be further strengthened.
In what cases can sealant be used?
Any holes in the exhaust system must be repaired immediately while they are small. Otherwise, you are unlikely to be able to do without contacting a car service. You can limit yourself to sealant if the area of damage is comparable to the size of a pin head.
In this case, you can safely take on the repairs yourself.
it possible to seal the exhaust manifold by cold welding if the hole is larger than a coin or longitudinal? Yes, hot melt adhesive can also cope with this task, but the work will require more effort.
Carrying out work
First of all, it is necessary to degrease the repair area using a solvent. The glue itself is mixed immediately before starting work.
Repairing minor damage
- The crack is drilled along the edges with a drill, which relieves the internal stress of the metal.
- If the hole has a diameter of no more than 10 mm, it is covered with a layer of sealant of 5-7 mm, around the perimeter - 8 mm.
- Initial setting takes 5-20 minutes, during which time it is still possible to correct the shape without mechanical treatment.
- After 4 hours, you can warm up the unit to operating temperature.
- If the repaired area experiences pressure while the car is in operation, the patch is fixed with clamps for additional mechanical strength.
If you notice that the hot-melt adhesive is bubbling, you need to remove the composition, more thoroughly degrease and dry the surface, and only then begin repair work again.
Repairing major damage
Larger holes can be repaired with stainless steel patches. Hot melt adhesive is also used in this case.
- The edges of the crack are processed and burrs are removed.
- The edges of the hole and the patch are coated with excess sealant.
- The patch is applied with an overlap of 30 mm over the damaged area.
Excess sealant is usually difficult to remove with solvent, so a file or power tool is used for this purpose.
You can purchase hot-melt adhesive and components for car repairs in the Tekhnichka-Express online store. We offer a huge selection of reliable auto parts from leading manufacturers.
Source:
https://tehnichka-express.ru/blog/mojno-li-vypusknoy-kollektor-zamazat-holodnoy-svarkoyHow to weld a cast iron manifold at home? — Machine tools, welding, metalworking
The exhaust manifold is one of the most important components of your vehicle. The simplest manifold consists of several pipes welded together into a single system through which exhaust gases are discharged. Every car has an exhaust manifold, regardless of its price or year of manufacture.
Since this is one of the most important components, it has to withstand enormous loads. Under such conditions, the collector is not able to operate properly and cracks and sometimes through holes form on it.
Especially if the car is old and maintenance has not been carried out often. In such situations, welding of the collector is necessary. With its help, you can repair the unit and not have to purchase a new one.
In this article we will tell you everything you need to know about welding exhaust manifolds.
Welding the exhaust manifold
One of the components of the internal combustion engine is the exhaust manifold. It wears out during use. This is typical for a car with any mileage. There are many reasons for the formation of cracks: from manufacturing defects, incorrect assembly to dynamic destruction. If a part fails, do not rush to replace the spare part.
Many car repair shops specialize in welding exhaust manifolds. Having a welding machine in the garage, you can restore the part yourself. This can be done in several ways. The collector is made of stainless pipes or cast iron. Both alloys can be welded, but each technology has its own nuances.
Experts are ready to share their experience.
How to weld a cast iron manifold
Cast iron is an alloy of iron and carbon, with a carbon content of more than 2%. Due to its low melting point compared to steel (1200 - 1250 °C), it quickly passes from the molten state to the solid state. In this case, pores form in the weld due to the intense release of gases from the weld pool, which continues during the crystallization stage. To correctly determine how to cook cast iron, you must consider the following features:
- accelerated cooling leads to the formation of a bleached layer (cementite) in the area near the seam and creates difficulties for its further mechanical processing;
- its high level with uneven heating or cooling causes cracks to appear during welding;
- the high fluidity of cast iron in a liquid state necessitates the use of preforming;
- strong formation of gases in the liquid bath causes porosity of welds.
How to brew cast iron
The connection of cast iron parts is carried out by gas, thermite, foundry, electroslag, arc welding, as well as soldering. Welding work is performed without heating (cold metal welding), with local or general heating of the product.
Hot welding
Forming the part
The process technology includes mechanical processing for welding, forming of welded parts, preheating, welding itself and subsequent slow cooling.
Preparing the defective area for welding involves thoroughly cleaning it and cutting the edges to be welded.
Elimination of through cracks or welding of defects at the edges of parts will be carried out using graphite molds, which prevent the flow of molten metal from the weld pool. The molds are made from graphite plates connected by a molding compound, which includes quartz sand mixed with liquid glass.
Arc welding with a cast iron electrode is performed using cast rods with a diameter of 8 - 12 mm, onto which special graphitizing coatings are applied. The coating composition includes ferrosilicon, thermite, graphite, marble, aluminum (powder), liquid glass and titanium ore.
Cast iron castings and parts are heated to 300 - 700 oC. Welding work is performed using cast iron electrodes or flux-cored wire with a ceramic rod additive.
Heating is carried out in special furnaces so that after welding the entire product is cooled evenly and cracks do not form.
Hot welding of cast iron is performed at high welding current without interruption until the defect is welded. For example, for welding with an electrode with a diameter of 8 mm, a current of 600 A is required, with a diameter of 12 mm - a current of 1000 A. The work is carried out with a constant current of reverse polarity.
Carbon arc welding of cast iron is performed using carbon or graphite rods. Cast iron rods are used as filler material, and to deoxidize and protect the bath, a flux consisting of industrial anhydrous borax ground into powder and calcined at 400 °C is used.
It is possible to use a mixture consisting of 23% technical borax, 50% sodium nitrate and 27% soda.
Welding with carbon electrodes with a diameter of 8 - 20 mm is carried out at a direct current of direct polarity of 280 - 600 A using PSM - 1000 converters, VAM - 1601 rectifiers, TDF - 1601 transformers.
During the welding process, continuous maintenance of a significant volume of liquid metal in the weld pool and its thorough mixing are required. In order for the welded parts to cool slowly, they should be covered with fine charcoal or dry sand.
Cold welding method
This type of cast iron welding is used more often. Preparation of defective areas involves cleaning, milling, drilling and other plumbing work until a clean metal surface is obtained. Defects located further than 20 mm from each other are drilled out or cut out separately; if they are located closer, the defective area is cut out completely.
Installing pins to strengthen the seam
In practice, several options for cold welding are used: copper-iron, copper-nickel, nickel, iron-nickel, steel and other electrodes.
By using copper-nickel and copper-steel electrodes, it is possible to obtain a deposited metal that is easy to process. Surfacing is formed by single-layer or multi-layer laying of beads.
Welding with steel electrodes is performed as follows. In order to form a durable layer of deposited metal, pins are inserted into the cast iron product, which are then scalded. This method is used when repairing bulky and heavy cast iron parts. With this method, the weld metal contains an increased amount of carbon, which increases its hardness and promotes the formation of cold and crystallization cracks. To reduce this hardness, two methods are used:
1. The carbon content is reduced by reducing the depth of penetration of the base metal, or the process of joining the metal is carried out over a layer of oxidizing flux containing up to 30% scale, which acts as a carbon oxidizer.
2. The structure of the weld metal and its chemical composition are obtained, close to the structure of gray cast iron, which is achieved by applying a thick layer of graphitizing coating to the steel rod, which contains 30% graphite and 30% ferrosilicon. Steel electrodes are widely used in the repair of small non-critical cast iron products that do not require any processing after welding.
Cold welding zone
Copper-iron electrodes are used for welding individual defects or small discontinuities that cause leaks on critical castings operating under pressure.
The deposited metal from these electrodes is perfectly processed.
The welded joint is a mechanical mixture of an iron-carbon alloy and copper, connected to the base metal by common steel crystals, as well as by partial penetration of copper into the micropores of cast iron.
Copper-nickel electrodes are used mainly for welding casting defects on working surfaces on which a local increase in hardness is unacceptable.
Iron-nickel electrodes are used for welding individual small defects on critical surfaces of castings made of gray or high-strength cast iron.
Nickel electrodes of the brand are used when correcting small defects in critical products.
Multilayer structure during welding work
Arc welding using electrodes made of austenitic cast iron, coated with a current-carrying layer and intended for welding casting defects and repair welding. Welding work is carried out with direct current of straight polarity. The conductive layer of electrodes has good electrical conductivity, so the arc burns alternately between the metal rod and the product, as well as between the product and the coating.
Gas welding of cast iron is rarely used and is limited to repair work (welding casting shells, surfacing worn surfaces, eliminating external defects). The best results are obtained by welding using an oxygen-acetylene mixture, so other flammable mixtures are practically not used for welding cast iron. Welding is performed with preheating, general and local.
For general heating, muffle furnaces, induction heaters, and furnaces are used that can heat small parts up to 300–400°C, and large parts up to 600–700°C. For local heating, gas burners or blowtorches are used. Due to the high fluidity of cast iron, welding is performed exclusively for the lower positions of the seam. The weld pool is protected by manually applied fluxes.
Mechanized welding methods and how to weld cast iron
Electric welding of cast iron (electroslag welding) provides satisfactory seam properties of the welded joint. In this method, cast iron plates are used as electrodes.
With the correct selection of electrodes and the use of fluoride non-oxidizing and desulfurizing fluxes, as well as slow cooling of the weld and heat-affected zone, characteristic only for electroslag welding, it is possible to obtain welds without cracks, bleached areas, pores and other defects that determine the quality of the welded joint.
Is it possible to weld cast iron in a protective gas environment?
The carbon dioxide arc welding method is very widely used, as it allows for a small penetration of the base metal. The performance of welded joints and the composition of the weld metal depend on the welding technique and mode, the size of the products, and the composition of the electrode wire. Using various welding modes and techniques, it is possible to obtain deposited metal with the required structure.
The best results are obtained when using 09G2SA wire with a diameter of 1 mm with a current value of no more than 100 - 120 A, an arc voltage of 18 - 21 V, and a welding speed of up to 12 m/h.
Using this method, you can join plumbing pipes made of gray cast iron, repair automobile and tractor parts that do not require further machining, and weld high-strength cast iron and steel.
Is it possible to cook cast iron with a semi-automatic machine?
In auto workshops, a client can weld a cast iron block using a semi-automatic machine without any problems. Welding cast iron semi-automatically at home is performed using flux-cored wire and gives fairly good results.
Source:
https://stroyka.ahuman.ru/chem-zavarit-chugunnyj-kollektor/
