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Repair of industrial equipment

Cleaning, washing and troubleshooting parts

Cleaning and rinsing of parts

After disassembling the machine, parts and assembly units must be cleaned and washed, since the cleaner the parts, the easier it is to identify defects in them. In addition, cleaning and rinsing contaminated parts improves repair sanitation.

Cleaning and rinsing should also be carried out when preparing parts for restoration or painting.

The parts of the repaired equipment are cleaned by the following methods: thermal (fire), mechanical, abrasive, chemical.

The thermal method consists in cleaning parts (removing rust and old paint) with a flame (blowtorch or gas burner).

With a mechanical cleaning method, old paint, rust and hardened oil deposits are removed from the parts with brushes, mechanized cutters, various manual machines and other portable mechanisms.

With the abrasive method, cleaning is carried out mainly by hydrosandblasting installations.

With the chemical method, old paint, grease, oil deposits and other contaminants are removed with a special paste or solutions consisting of quicklime, chalk, caustic soda, fuel oil and other components.

Rice. 1. Stationary washing machine

Mechanized washing of parts is carried out in stationary and mobile washing installations under the action of strong jets resulting from the supply of liquid by a pump under a certain pressure.

On fig. 1 shows a stationary washing machine, consisting of a washing chamber, above which eight tanks with washing liquid with a volume of m3 each are placed. Seven tanks with pyramidal bottoms, located on two sides of the installation, in addition to their main purpose, are also settling tanks. A solution of the following composition is used as a washing liquid: 2-3% soda ash; 0.3-0.5% detergent OP-7; 2-3% sodium nitrite; the rest is water.

From the tanks, washing liquid at a temperature of 80 ° C is pumped under a pressure of 0.6 MPa (6 kgf / cm2) into a pumping hydrant (pipe with 40 nozzles).

The liquid is heated by steam through tubular heaters mounted inside the tanks. The used solution flows into the pan with a grid, from where it is again supplied by a special pump to the tanks.

A closed monorail with eleven hangers passes through the washing chamber, which move with the help of a drive station (not shown in the figure) at a speed of 0.2 m/min.

Rice. 2. Mobile washing machine

Special baskets with loaded parts and assembly units are hung on suspension hooks using a cantilever beam and an electric hoist. Assembly units and parts are fed into the washing chamber through self-opening and closing multi-leaf doors.

Once a quarter, it is supposed to drain all the washing liquid through the dirt collector, rinse the tanks and fill in a new solution.

For washing parts directly at the workplace, mobile washing baths or washing machines are used; kerosene is used as a washing liquid. In baths, parts are washed manually, and in washing machines this process is mechanized.

On fig. 2 shows a mobile washing machine, consisting of a trolley with a fixed bathtub, in the lower part of which a mesh is installed.

For washing small parts, a shelf is attached to the side wall of the bath. The bath is closed with a lid.

A branch pipe is welded to the inclined planes of the bottom of the bath, through which the contaminated liquid is drained into a tank, which has partitions that form settling tanks in the tank. An electric pump is mounted in the tank, which pumps liquid through a pipe and a gasoline-resistant hose to flush parts.

Troubleshooting parts

After washing, scratches, cracks, dents are clearly visible on the surfaces of the disassembled parts, and it is possible to measure the parts with the necessary accuracy during troubleshooting.

Troubleshooting of washed and dried parts is carried out after they are assembled according to assembly units, which must be done carefully and carefully. Each part is first examined, then its shape and dimensions are checked with an appropriate calibration and measuring tool. In some cases, the interaction of this part with others associated with it is checked to determine whether it is possible to repair this part or it is more expedient to replace it with a new one.

Information about the parts to be repaired and replaced is entered in the list of defects for equipment repair.

A properly drawn up and sufficiently detailed list of defects is an essential factor in preparing for repairs. This responsible document is usually drawn up by an equipment repair technologist with the participation of the foreman of the repair team, the repair shop foreman, and representatives of the Quality Control Department.

In case of flaw detection, it is important to know and be able to assign the values ​​of wear limits for various parts of equipment and the allowable limit repair dimensions. For example, it is allowed to reduce the thread diameter of lead screws - 8% of the nominal diameter; reduction in the diameters of shaft necks, spindles and axles - 5-10% of the nominal diameter; reduction of the wall thickness of hollow spindles and axes - 3-5% of the nominal thickness.

Parts are sorted into three groups: the first - suitable for further operation; the second - requiring repair or restoration; the third - unusable, to be replaced.

Repair is subjected to labor-intensive parts, the restoration of which is much cheaper than newly manufactured ones. The repaired part must have a significant margin of safety, which allows to restore or change the dimensions of the mating surfaces (according to the system of repair dimensions), without reducing (in some cases increasing) their durability, while maintaining or improving the performance of the assembly unit and unit.

Parts must be replaced if their reduction in size as a result of wear interferes with the normal operation of the mechanism or causes further intensive wear, which leads to the failure of the mechanism.

When repairing equipment, parts with wear limit are replaced, as well as parts with wear less than permissible if, according to calculations, they do not last until the next repair. The service life of parts is calculated taking into account the wear limit and the intensity of their wear under actual operating conditions.

When troubleshooting, parts must be marked with the serial number of the list of defects, as well as the inventory number of the machine or machine tool, this facilitates further repair operations.

Marking is carried out with stamps, paint, tags, electrograph or acid. Branding stuffs designations on non-working surfaces of non-hardened parts. In other ways, both hardened and non-hardened parts are marked. For example, when marking non-hardened parts, a rubber stamp is wetted in a solution of 40% nitric acid, 20% acetic acid and 40% water; when marking hardened parts - in a solution of 10% nitric acid, 30% acetic acid, 5% alcohol and 55% water (for hardened parts); the wetted stamp is applied to the non-working area of ​​the part to be marked. After exposure for 1-2 minutes, the surface is neutralized by wiping with a swab dipped in a solution of soda ash.

Parts that are decided to be replaced during troubleshooting are stored until the repair of the mechanism is completed, they may be needed to draw up drawings or make samples of new parts.

Washing the parts before the start of the repair of the car contributes to the high quality of its repair. When repairing, for example, a car engine, manual washing and automatic washing are used. Hand washing is usually done at small repair shops. Using a manual sink, the part or assembly is installed on a special pallet. A sink is created with a detergent and a brush. Gasoline, kerosene or soda solution is used as a detergent.

Gasoline is a less successful cleaning fluid. Its disadvantage is the highest vapor volatility. And this is related to its toxicity. Gasoline is especially unsafe when working indoors. Gasoline vapors generally aggravate the environment. Gasoline does not completely wash off small particles of dirt or abrasive dust after repairing parts. Gasoline has a negative effect on the cuffs and seals of parts and assemblies that are made of rubber. The only advantage of gasoline is that oil pollution quickly dissolves in it. After degreasing parts with gasoline, from time to time you can find any flaws on their surface.

Vapors of kerosene, unlike gasoline vapors, are actually not volatile. The washing characteristics of kerosene are significantly worse than those of gasoline. After washing in kerosene, the parts remain oily. By this they are quite "attract" dust particles. Therefore, kerosene during repairs can only be used as an auxiliary substance.

Soda solution differs from gasoline and kerosene in that it is non-toxic and completely harmless. True, it has an irritating effect on the skin of the hands. Its disadvantage is that it is effective only when heated. If the details of a complex configuration and at the same time are very dirty, then the soda solution will be difficult to wash off. And in duralumin parts, it causes corrosion. In small workshops it is used occasionally. He asks for heating and frequent changes of solution.

Other detergents are also used. In large repair shops, manual washing is not used so extensively due to low productivity. For this reason, washing installations are used at medium and large repair enterprises. These installations provide washing of parts with heating and the upcoming cleaning of the dirty solution. Installations have the highest efficiency. But manual washing cannot be completely excluded from the repair process, since very dirty parts are still subjected to preparatory cleaning by hand.

Washing is a series of operations that are performed in the following sequence:

1) the external surfaces of the parts are cleaned from dirt;

2) clean the internal cavities and channels of parts from carbon deposits and wear particles;

3) the surfaces of the sealing parts are washed;

4) wash the parts themselves;

5) purge the internal channels and dry the parts.

At different washing steps, also depending on the contamination of the parts, different detergents are used. If the engine is very dirty on the outside, then mechanical cleaning of the surface is usually done first with steel brushes. Such brushes are also used for preparatory cleaning of the internal channels of parts from carbon deposits. Cleaning is done very carefully so as not to throw the deepest scratches on the surface.

It happens that after washing the parts, it is necessary to re-do mechanical cleaning. In order to soften the dirt, they are usually dipped in a washing solution beforehand. It happens that blowing out the internal channels is enough to clean dirt and chips. Compressed air is used for blowing. Increased attention should be paid to the intake manifold of the motor, which is damaged. It is not necessary to wash parts that have closed rolling bearings. Together with the detergent, dirt can get into such bearings. The detergent can completely wash away the grease. And this leads to a quick failure of the bearings.

Very dirty external surfaces of such units must be wiped with a rag, which is slightly moistened with washing liquid. Despite the importance of the process of washing parts, in practice, washing is often neglected. Car parts are sometimes not washed at all, and if they are, then somehow. This happens due to a complete misunderstanding of the processes that occur in the car. And the consequences of such a misunderstanding can be quite severe. In our article "Washing and cleaning of car parts" we tried to explain to you the full significance of this process.

After disassembling the machine, the assembly units and individual parts must be cleaned and washed from dirt, chips, foreign particles, soot, grease, coolant in order to identify defects, improve sanitary repair conditions, and also to prepare parts for restoration and painting operations.

Parts cleaning methods:

Mechanical. Rust, old paint, hardened lubricant, soot, etc. are removed from parts with manual or mechanized brushes, cutters, scrapers, scrapers, and various machines.

Abrasive. Cleaning is carried out using sandblasting or hydrosandblasting of the part.

Thermal. Old paint, rust is removed by heating the surface of the part with the flame of a blowtorch or gas burner.

Chemical. Remains of lubricant, coolant, old paint are removed with special pastes and washing solutions, which include caustic soda, quicklime, chalk, fuel oil, etc.

Parts are washed with aqueous alkaline solutions and organic solvents. First in a hot solution, then in clean hot water. After that, the part is thoroughly dried with compressed air and napkins. In alkaline solutions, parts with elements made of non-ferrous metals, plastics, rubber, fabrics are not washed. Parts with polished and ground surfaces should be washed separately.

Parts washing methods:

1. Manual. Washing is carried out in two baths filled with an organic solvent (kerosene, gasoline, diesel fuel, chlorinated hydrocarbons).

2. In tanks by immersion. Washing is carried out in a stationary or mobile tank with a grid on which the parts are laid, and a tube with an electric spiral or a coil for heating the washing solution to a temperature of 80-90 ° C.

3. In washing machines. Stationary or mobile machines of various designs.

4. Ultrasonic. Rinsing is carried out in a special bath with heated washing liquid (alkaline solutions or organic solvents). A source of ultrasonic vibrations is placed in the bath, which creates high-frequency elastic waves that accelerate the separation of contaminants from the surface of the part.

Parts detection

Cleaned parts are subjected to fault detection in order to assess their technical condition, identify defects and determine the possibility of further use, the need for repair or replacement. During fault detection, the following are revealed: wear of working surfaces in the form of changes in the dimensions and geometric shape of the part; the presence of crumbling, cracks, chips, holes, scratches, scratches, scuffs, etc .; residual deformations in the form of bending, twisting, warping; change in physical and mechanical properties as a result of exposure to heat or the environment.

The detection of washed and dried parts is carried out after they are assembled according to the nodes, which must be done carefully and carefully. Each part is first inspected, then its dimensions are checked with an appropriate checking and measuring tool. In some cases, the interaction of this part with others associated with it is checked.

Methods for detecting defects:

1. External examination. Allows you to identify a significant part of the defects: holes, dents, obvious cracks, chips, chipping in bearings and gears, corrosion, etc.

2. Check by touch. The wear and tear of the threads on the parts, the ease of rotation of rolling bearings and shaft journals in plain bearings, the ease of movement of gears along the splines of the shaft, the presence and relative size of gaps in mating parts, the density of fixed joints, etc. are determined.

3. Tapping. The part is lightly tapped with a soft hammer or hammer handle to detect cracks, the presence of which is indicated by a rattling sound.

4. Kerosene test. It is carried out in order to detect a crack and its ends. The item is either immersed in kerosene for 15-20 minutes, or the alleged defective place is lubricated with kerosene. Then carefully wipe and cover with chalk. Kerosene protruding from the crack will moisten the chalk and clearly show the boundaries of the crack.

5. Measurement. With the help of measuring tools and means, the amount of wear and gap in the mating parts, the deviation from the specified size, the errors in the shape and position of the surfaces are determined.

6. Hardness test. Based on the results of measuring the surface hardness of the part, changes that have occurred in the material of the part during its operation are detected.

7. Hydraulic (pneumatic) test. Used to detect cracks and cavities in body parts. For this purpose, all openings in the body are muffled, except for one, through which fluid is injected under a pressure of 0.2-0.3 MPa. Leaking or fogging of the walls will indicate the presence of a crack. It is also possible to inject air into the housing immersed in water. The presence of air bubbles will indicate an existing leak.

8. Magnetic way. It is based on a change in the magnitude and direction of the magnetic flux passing through the part in places with defects. This change is recorded by applying ferromagnetic powder to the tested part in dry or suspended form in kerosene (transformer oil): the powder settles along the edges of the crack. The method is used to detect hidden cracks and cavities in steel and cast iron parts. Stationary and portable (for large parts) magnetic flaw detectors are used.

9. Ultrasonic method. It is based on the property of ultrasonic waves to be reflected from the boundary of two media (metal and void in the form of a crack, shell, lack of penetration).

10. Luminescent method. It is based on the property of some substances to glow in ultraviolet rays. A fluorescent solution is applied to the surface of the part with a brush or by immersion in a bath.

The list of defects lists in detail the defects of the machine as a whole, each node separately and each part to be restored and hardened. A correctly compiled and sufficiently detailed list of defects is an essential addition to the technological repair processes. Therefore, this very important technical document is usually compiled by the technology for the repair of equipment with the participation of the foreman of the repair team, the foreman of the repair shop, representatives of the Quality Control Department and the customer shop.

Detection of washed and dried parts is carried out after they are assembled by units. This operation requires a lot of attention. Each part is first inspected, then its dimensions are checked with an appropriate calibration and measuring tool. In some cases, the interaction of this part with others associated with it is checked.

The list of defects lists in detail the defects of the equipment as a whole, each unit separately and each part to be restored and hardened.

When disassembling the equipment to be repaired into components and parts, the control and sorting of the ero parts into the following groups is carried out: 1) suitable for further operation; 2) requiring repair or restoration; 3) unusable, subject to replacement.

Similar information.

Cleaning parts and surfaces of assemblies and assemblies is a necessary procedure to maintain mechanisms in working condition. In addition, cleaning maintains the degree of performance at the required technological level, and is also an important tool in identifying defects and the degree of deterioration of engines and their individual components.

Thus, this procedure gives a diverse effect. The presence of different methods and detergents allows you to choose the best ways to clean parts in a particular case.

Cleaning parts with traditional methods

Traditional cleaning technologies include the use of the most common means, such as kerosene and gasoline, to remove contaminants. These are hydrocarbons similar in action with a pronounced toxic effect, which allows you to clean units and various components. Toxic components literally “corrode” scale and dirt, as well as deposits of fuel oil and technical oils.

The undoubted advantages of using these substances include their availability. Gasoline, and sometimes kerosene, are common substances that can be found in any garage or any industrial plant. But this is where the advantages of this method of cleaning parts end, at the same time, the list of negative factors includes several points. Among them are:

• Danger to the health of the worker and to the health of all those around him who are in the room. When heated, kerosene begins to release toxic volatile substances, the inhalation of which can lead to chronic or acute diseases of the lungs, liver, and heart. The same applies to gasoline, but its volatile properties are manifested even in a cold state. A person develops symptoms similar to those of alcohol intoxication, which can lead to pulmonary edema or, for example, cardiac arrest. In addition, if these substances come into contact with the skin or mucous membranes of the organs of vision and breathing, they will cause redness, burning, etc. Therefore, when working with gasoline and kerosene, it is necessary to use protective equipment - rubber gloves, respirators or cotton-gauze bandages, goggles and special clothing. The same applies to other workers in such a room. In addition, the room where this method of cleaning parts is used must be well ventilated or equipped with a powerful ventilation system.
• Danger for the environment. Gasoline and kerosene should be stored away from sunlight and heating elements in tightly sealed containers. Disposal of waste liquids must be carried out taking into account their high toxicity.
• The need to adhere to the strictest security measures. Any spark can cause a fire and even an explosion, therefore, when working with gasoline and kerosene, do not smoke, use open flames, etc.

The high level of danger and the difficulty of working in cramped conditions make these substances inconvenient and ineffective when used as detergents.

Cleaning parts with innovative methods

Ultrasonic technology is one of the innovative ways to clean parts. This method allows you to clean components and assemblies using non-linear effects, the most important of which is cavitation erosion. Cavitation means the formation of tiny bubbles in a bath with a part immersed in an aggressive washing liquid, which, when collapsed, destroy contaminants. This technology is more environmentally friendly than the technology of processing units with gasoline or kerosene, but its use also leads to the appearance of volatile substances.

There are other negative aspects as well:

• The ultrasonic device has a rather complicated device and high cost. This leads to high maintenance and repair costs.
• If multiple cleaning steps are required, the worker will have to manually move the parts crate between baths. If you install a production line for this, it will also lead to an increase in the cost of the process.
• Ultrasound increases the physico-chemical reactions in an aggressive detergent. If you choose the wrong mode or composition, instead of cleaning from contaminants, the worker can damage the part. That is, ultrasonic technology requires a highly qualified specialist.

Of course, this technique is better and more efficient than gasoline cleaning, but there is an even simpler, more effective and low-cost way to bring the engine, mechanisms and their individual components to a perfectly clean state.

The unique way to clean parts from IBS Scherer

The German developer - concern IBS Scherer GmbH has been operating on the market for 50 years and is a leading manufacturer of safe and effective detergents and equipment for cleaning parts. The company's product range includes a large number of options for washing machines and compositions with pronounced properties, which makes it possible to choose the best option without the presence of a specialist.

The development of a German company is as simple as possible:

• The equipment consists of a portable pump, footswitch, hose, brush, washer and reservoir. A minimum of parts allows you to work without training and special knowledge, in addition, simplicity reduces maintenance costs and increases the mobility of installations.
• Detergents have different characteristics, for example, they can apply an anti-corrosion oil film on parts and include fragrances in their composition. They also have different freezing, drying temperatures, and other features.

When working, it uses closed-cycle technology, which allows the use of one tank with a harmless to humans and the environment, but effective detergent composition for one year.

You can learn more about IBS Scherer technologies in the relevant sections, and to clarify the details, it is better to contact our professional consultants in any convenient way.

The quality of overhaul and maintenance directly depends on the quality of parts washing. Washing and cleaning of parts begins with the preparatory stage - the process of disassembling the equipment. Then comes the turn of thorough cleaning and disinfection of all elements of the processed mechanism.

The optimal type of cleaning is selected based on the following data: the specifics of the contaminants present, the nominal dimensions of the parts, the inaccessibility of deposits, the material of manufacture of the product, etc.

Consider possible options, using the example of machines involved in road work. This equipment generates the following contaminants:

• non-fat deposits (dust, road debris, dirt, etc.)
• oil stains
• traces of lubricants
• scale
• corrosion
• technological and carbon deposits
• residues of cement, concrete, etc.

Oil-mud and non-grease stains

The easiest way to remove traces of non-fat and oil-mud contaminants. They are formed on all elements of road machines, it is simply impossible to prevent the process of their appearance during the operation of the equipment. Washing this type of deposits does not require the use of special cleaning agents, a sufficiently powerful jet of water.

Another common type of contamination is deposits of coolants and lubricants. All parts of machines that are designed to work in a lubricating environment bear traces of this nature. Specialized equipment and special detergents are used to clean such stains.

carbon pollution

More difficult to get rid of carbon deposits. They are formed in the process of thermal oxidation of fuels and lubricants. Most often, this kind of pollution affects internal combustion engines, but can also be present on the outer body of a road car, in the form of bitumen or asphalt mixture. Carbonaceous deposits differ in the degree of oxidation intensity: deposits, varnish deposits, films, asphalt-resinous pollution, etc.

Consider soot. It is a by-product of the combustion process. Small non-combustible particles settle on the internal elements of the engine and gradually sinter, forming a dense layer of pollution. Another type of carbon deposits are lacquer films, they are formed due to the heating of thin layers of oil. These films attack pistons, crankshafts and other moving parts of road vehicles.

The sticky, mud-like mass that settles in filters and channels is called lacquer sediment. It is the result of oil and fuel oxidation. But asphalt-resinous deposits arise in the process of interaction of high temperatures and access to fresh air. Outwardly, they look like small solid particles, which, during the operation of the mechanism, can become harmful abrasives for moving elements.

It is necessary to remove all types of carbon deposits from road machine parts on a regular basis. The cleaning process will require highly specialized cleaning equipment and specialized cleaning solutions.

Scale and corrosion

The deposition of potassium and magnesium salts on the surfaces of parts is called the process of scale formation. The optimum temperature for the generation of this type of pollution is heating above 85°C. Scale adversely affects the operation of the internal combustion engine as a whole. After all, the indicators of its thermal conductivity are much lower than those of the metal, so the motor elements can overheat and fail.

A thin coating of scale can significantly reduce the performance of any engine, increase fuel consumption and wear on internal parts. Complete removal of deposits is not an easy process, it will require a lot of time and labor.

Corrosion is formed due to the destruction of the surface structures of metal parts. This process is caused by electrochemical reactions inside the road car.

Technological dirt

When assembling and running various mechanisms, there is a threat of technological pollution. At its core, these are the remains of chips, grinding surfaces, lapping lubricants, etc. To organize the smooth operation of the equipment, it is necessary to get rid of this kind of pollution. They adversely affect the operation of machines, lead to early wear of parts and destruction of connecting elements.

Road installations work with mortars of cement and concrete, so it is not surprising that the contact elements of the mechanisms bear traces of these building materials. Removing this kind of contaminants is a complex and time-consuming process, which is an urgent need.

Pollution Control Methods

In the repair and maintenance industry, there are the following methods for cleaning machine parts:

• ultrasonic cleaner
• mechanical cleaning
• physical and chemical impact on existing pollution

The ultrasonic cleaning option occurs due to the transmission of high-frequency sound to the surface to be treated through a liquid conductor. The principle of operation is quite simple. Sound vibrations (at 20-30 kHz) provoke the appearance of a series of bubbles in the liquid, which subsequently burst, creating a powerful blast wave. An impact of such force removes carbon deposits from the surface of the workpieces in 2-4 minutes, and oil films in 40 seconds.

The ultrasonic cleaning method is effective for processing complex and embossed surfaces, such as engine parts, carburetors or compressors.

Mechanical cleaning of parts is the most primitive and time-consuming, but some contaminants can only be treated in this way. In manual mode, machine elements are washed with brushes or metal scrapers using dry abrasives.

The physicochemical method of removing contaminants is quite universal. It copes with almost any type of deposits and can be jet or carried out in special baths. The working material is a washing liquid (aqueous solution), heated to certain temperatures (from 60°C to 95°C). The main cleaning element of the installations is the strength and intensity of the liquid supply. A powerful jet treats all surfaces of parts, removing dirt from the most inaccessible areas.