How to clean metal to a shine. How to polish stainless steel: ways and means to give an expressive shine. Combined processing methods

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METAL CLEANING

1. CLEANING GOLD

a) Gold rings can be cleaned of iodine stains by immersing the ring for a quarter of an hour in a solution of 1 teaspoon of hyposulfite in a glass of water.

b) Cleaning matte gold. They take 80 bleaching powder, 70 bicarbonate salt and 20 table salt. Pouring a mixture of 3 mugs. distillation water, it is kept in sealed bottles. Blackened objects are placed in a cup and doused with pre-shaken liquid and left alone for a while. Sometimes the mixture is heated. After taking out the objects, they wipe them, rinse with alcohol and put them in sawdust to dry.

c) Gold items are cleaned with a powder consisting of 16 chalk, 6 1/2 clay, 4 white lead, 1 1/2 magnesia and 1/2 bloodstone, or 80 iron oxide (kolkotar) and 30 ammonia.

2. SILVER CLEANING

a) Silver items can be cleaned by placing them for several minutes in a hot aqueous solution of cream of tartar (cremortartar) and then thoroughly rubbing with suede.

b) Silver spoons will always be clean and shiny if, immediately after use, they are washed in boiling water, to which a small amount of soda is added, and poured over with clean hot water, and then wiped dry with a soft towel. Once a week, spoons should be washed in soapy water with a small amount of ammonia. Thanks to this, even a completely tarnished spoon becomes shiny and looks just like new. dark spots silver spoons coming from eggs are removed by rubbing with ashes. Damp stains come off by washing in warm vinegar followed by rinsing in clean water and wiping dry.

c) It is known that both silver and silver-plated items tarnish relatively quickly in the air and acquire a very ugly appearance. To eliminate such tarnishing, the following is recommended. remedy: a liquid solution of collodion is prepared and this solution is used to smear silver or silver-plated objects with a thin and possibly even layer: the alcohol evaporates quickly and a thin, completely invisible film of collodium remains on the metal surface, which perfectly protects silver from tarnishing under the influence of air or gases in it . As shown by experiments carried out in foreign museums, silver coated with a thin layer of collodion retains its color, luster and polish for a long time. If necessary, this thin protective layer can be easily removed with hot water or even better with alcohol.

d) Silver items are first cleaned with water and soap, and their still warm surface is smeared with a solution of 1 sodium sulphate (hyposulfite) in 3 water, after which they are wiped with a rag.

3. CLEANING COPPER.

a) Objects made of polished copper are first wiped with a soft cloth soaked in kerosene, then cleaned with a woolen cloth with powdered chalk or Viennese lime. Heavily neglected copper objects are restored to their shine by wiping the object with a rag soaked in dilute hydrochloric acid. Then clean as above, or dissolve in 1 liter of water 30 g of oxalic acid, add 4 tablespoons of alcohol, 3 tablespoons of turpentine. After that, the liquid is shaken well and bottled for storage. When used, the object to be cleaned is lightly wiped with this liquid, and then wiped with a dry linen cloth: copper is quickly cleaned and becomes shiny. b) Mix 1 oxalic acid, 25 red iron oxide, 20 tripoli, 60 palm oil, 4 paraffin. It turns out a paste that perfectly cleans things made of copper and brass.

c) Red iron oxide (Caput mortuum), in the form of a delicate red powder for cleaning copper and brass objects, is obtained by heating iron sulphate until it dissolves into a white powder. This latter is then heated in a crucible, and a delicate red powder of iron oxide is obtained.

d) Mix a transparent powder of ferrous sulfate with the same solution of potassium oxalate. The resulting yellow precipitate is washed, dried and heated as above.

e) Mix 9 crude oleic acid with 1 kerosene, which can be dyed with alkannin or infusion with an alkane root.

f) You can refresh the surface of small copper products by boiling them for 30 minutes in a solution of soda ash (40 g / l).

g) Products made of copper and brass retain their luster if they are carefully rubbed with wax.

h) Darkened copper cleans raw potatoes well.

4. CLEANING OF THE GILDED BRONZE,

a) They take 5 glasses of water and dissolve alum in it until saturated, then boil the solution on fire until it is hot, rub the darkened place with a cloth until the stain comes off. b) Boil yellow peas, grind it until a thick dough is obtained and, while still warm, stick around a bronze thing with it. After a few hours, when the pea dough shrinks, the bronze is washed clean with boiling water and wiped dry with a clean rag. All rust and all stains will come off.

b) Bronze parts can be cleaned with a raw potato or a stiff hair brush dipped in hot vinegar. After that, the part must be wiped with a soft cloth,

5. CLEANING NICKEL.

Nickel items to be cleaned are first moistened 2-3 times with a mixture of 50% alcohol (or vodka) and 1 sulfuric acid, then they are rinsed with water and washed with alcohol (or vodka), wiped with a thin linen cloth.

Nickel-plated surfaces of various objects can be cleaned with cigarette ashes, pouring it on a damp cloth.

Rust on nickel is removed as follows: smear the object with some kind of fat and leave it for several days, then wipe it thoroughly with ammonia. If the rust has penetrated deeply, instead of ammonia, you can take diluted hydrochloric acid, which, however, is left on the metal for no more than a minute. Then the object is washed with water and polished with chalk and crocus.

If the nickel layer is covered with a bluish coating, then it is washed with a mixture of alcohol and sulfuric acid in equal parts by volume. Rinsing lasts only a few seconds, then the item is washed with water and alcohol and wiped to dryness.

6. CLEANING ZINC.

Zinc things are cleaned perfectly with a solution of 1 hydrochloric acid in 2 water. This solution is rubbed with a brush over the object to be cleaned until the dirt leaves behind. Then, when the object is not yet dry, lightly oil it with wood oil and rub it with finely ground chalk with a cloth until a shine is obtained.

7. CLEANING STEEL.

A simple and good composition for this purpose is a mixture of paraffin and oil. 1 paraffin is added to a flask for 20 oil, thoroughly shaken until the paraffin is completely dissolved and, having previously wiped the object to be cleaned, cover it with the indicated mixture with a brush; then leave for 10-12 hours. in place, protecting from dust, after which the object is wiped with a dry woolen cloth. If a steel tool or any other object requires thorough cleaning, due to its significant rust, etc., then the following composition is used: a mixture of 5 turpentine and 25 stearin oil is prepared. This mixture is diluted with alcohol until a thick liquid is obtained, which covers the object, and when the alcohol evaporates, the metal surface is wiped with a mixture of 45 animal coal and 25 kolkotar (mummy) in powder.

8. CLEANING OF METAL PARTS OF MACHINES.

"Moniteur Industriel" indicates the following the best way practiced in France. 10% of paraffin is added to one liter of kerosene and, having properly corked the vessel, set it aside for a day, shaking from time to time, after which the mixture is ready for use. Then, with the help of a cloth, all the metal parts of the machines to be cleaned are moistened with it. After moistening, leave in this form overnight (or even better for a day) and only the next day wipe dry with a clean cloth.

With this method of cleaning, rust, greasy tar dirt, etc., disappear, and the metal parts of the machines seem to be re-polished. There is no other way to clean them so well, not to mention the extreme cheapness of this method, which makes it quite suitable for cleaning all kinds of machines, tools, and in general products made of steel and polished iron.

POLISHING METALS

POLISHING OF METALS ASSOCIATED WITH CHEMICAL CLEANING

1. POLISHING IRON.

Iron products to be polished are immersed for some time in a mixture of 1 sulfuric acid to 20 by volume of water, then the object is removed, rinsed thoroughly with water and dried in sawdust. After drying, it is immediately immersed for one or two seconds in nitric acid, after which it is rinsed again with water, dried again in sawdust and then thoroughly wiped. In this case, the surface of the object becomes shiny, like glass. According to "Cosmos"a, no other way can achieve such perfect polishing as the above.

2. POLISHING STEEL.

Steel products are polished with a leather mug coated with a mixture of 16 tin and 1 zinc. A crocus or bloodstone moistened with alcohol is applied to the flat side of the mug and, after moderate drying, polished with agate.

3. POLISHED BRASS.

Equal parts water and ox bile boiled together make a good polish. The liquid, after cooling, is bottled and stored in them. When used, it is applied to brass and bronze objects with a brush or polished objects are dipped into it.

4. NICKEL POLISHING.

The mixture consists of 8 stearin, 32 lard, 2 stearin oil and 48 finely crushed Vienna lime. Objects are polished with this paste using a circle pasted over with cloth (according to Hildebrand).

5. POLISHING ALUMINUM.

a) Aluminum is immersed first in a strong solution of caustic potash or sodium, and then in a mixture of 2 nitric acid and 1 sulfuric acid. After that, it is placed in pure nitric acid and, finally, in vinegar diluted with water. After rinsing well in running water, dry in hot sawdust and polish with a polisher. Aluminum treated in this way acquires its natural pure white color.

b) 1 each of stearic acid and clay, 6 tripoli. If it is a matter of polishing smooth surfaces, then the paste is applied to a leather circle. After this treatment, the object is polished with another crocus using a leather mug, which makes the shine even more beautiful.

c) If polished by hand, then the most suitable is a mixture of vaseline and ceresin or a solution of borax in hot water, to which a few drops of ammonia are added.

6. POLISHES FOR METALS.

a) 90 g of finely sifted tripoli and 90 g of guinealithic acid are triturated with 450 g of liquid paraffin. After strong shaking, rub with a woolen cloth and polish with suede.

b) 60 Paris paint (pure iron oxide), 10 wax, 30 oleic acid and 2 rosin. From the addition of gasoline, iron oxide is mechanically distributed in the liquid, and large grains of polish sink to the bottom, and when drained, an elutriated mass is obtained that does not form scratches on the metal at all.

c) Equal parts of iron sulphate and table salt rub well in a mortar and the mixture is heated in a flat crucible or other vessel to a red heat. Various chemical glassware at affordable prices can be ordered on the site moslabo.ru. In this case, vapors are formed, and the mass turns into a liquid. When the vapors no longer rise, the vessel is removed from the fire and allowed to cool. The resulting brown mass is washed with water to remove all undecomposed ferrous sulfate particles. The remainder is an excellent polishing powder.

7. MEANS FOR POLISHING ALUMINUM.

According to Morny, equal parts of olive oil and vodka are mixed in a bottle by shaking until the liquid resembles an emulsion. The polishing stone is dipped into the emulsion, and the aluminum is polished like silver, but without applying too much pressure. The black streaks that sometimes form from the polishing stone are not harmful, but they can be removed from time to time with a soft cloth.

8. POINTING A MAT ON ALUMINUM.

First, aluminum objects are launched for 20 seconds. in a hot 10% solution of caustic soda, which is previously saturated with common salt in a cold state. Then the objects are rinsed with water and rubbed with a brush, after which they are again immersed for 30 seconds in the above solution. After a second rinse and washing in hot water, the objects are dried in sawdust.

9. POWDER FOR MATCHING JEWELRY.

Consists of 40 g of saltpeter, 25 g of table salt and 35 g of alum. Mix into a homogeneous mass and heat in an enameled vessel, with constant stirring with a glass rod, until water vapor escapes. Then cool the mass by placing the vessel in cold water, turn into powder and store until use in well-closing glass vessels.

If the objects are to be only partially made matt, then the parts that are to remain shiny are covered to matting with a layer of the following mixture: 50 g of carbonic lime in powder, 5 g of sugar and 5 g of gum arabic are triturated with water into a slurry, which is applied with a brush to remaining shiny areas.

10. FINAL FINISHING OF MACHINE PRODUCTS.

To give locksmith products a beautiful look, they resort to various means, depending on the nature of the work. Small artistic forgings acquire a beautiful appearance if, at the end, they are supplied with an intense black color. But for such works, the paint is not applied by spreading, but the following operations are performed: a fire is lit in the furnace, corresponding in size to the size of the object being processed. The fire should not smoke (it is best to use coke for this). Then they lubricate the object with ordinary linseed oil and expose it to the action of fire, but only for such a time until the oil evaporates and its residue burns to the iron. After cooling, rub the object firmly with a cloth lightly soaked in linseed oil.

The smoother the surface of the iron received during processing, the more beautiful the deep black color will look. This coloring is extremely strong and perfectly protects from atmospheric influences.

In order to pickle iron parts black, they must be clean, brilliantly straightened and polished. Then they are lubricated with liquid oil and sprinkled with wood ash, then they are held over hot coals until a run-down black color is obtained. After cooling, the objects are washed in water to which a few drops of sulfuric acid are added, and immediately wiped thoroughly with a coarse, clean cloth.

Rubbing with oil protects the product from exposure to air.

Fly marks on scales, panels and other parts are very difficult to remove with gasoline, alcohol and other solvents. At the same time, these stains disappear without a trace if the contaminated areas are wiped with a cloth or cotton wool moistened with saliva.

To make iron particularly soft, it is heated red-hot, quickly cooled in soap, heated again to red heat, and, after laying lime powder, is allowed to cool slowly. When processed in this way, the iron becomes very malleable and soft.

CLEANING THE GILDING.

Cleaning gilding, especially on wood, requires very careful handling. Previously, all dust must be swept away from the gilding, then the gilding is carefully wiped with a soft sponge, even better with a piece of cotton wool slightly moistened with wine alcohol or turpentine.

Instead of these liquids, good strong beer, a solution of the so-called Marseille soap, or a mixture of 10 parts of ammonia and 40 parts of soap alcohol are also used.

Egg whites are also considered a good cleaning agent for gilding, with which the object is carefully wiped with a piece of flannel.

You can use a mixture of proteins (2-3 eggs) with 18 g of sap water; With this liquid mixture, using a soft brush, lightly wipe the gilding, especially the most tarnished places.

Finally, pure wine vinegar can serve the same purpose, with which the gilding is covered with a soft brush, sponge, or piece of stalemate. After 5 minutes, the vinegar is carefully washed off. clean water without wiping anything.

For cleaning gilded bronze, in addition to ammonia diluted with water, the following method also gives good results: the gilding is wiped first of all with a brush moistened with water. Then cover with a soft brush with a mixture of 60 parts of water, 15 parts of nitric acid and 2 parts of alum, after which the liquid is allowed to dry without wiping.

CLEANING OF METAL PARTS OF MACHINES.

Here is the best method, now practiced in France, for cleaning metal parts of various kinds of machines. 10% paraffin is added to one liter of kerosene and, having clogged the vessel well, leave it for a day, shaking from time to time, after which the mixture is ready for use. Then, with the help of a cloth, all the metal parts of the machines to be cleaned are moistened with it. After moistening, leave in this form overnight (or even better for a day) and only the next day wipe dry with a clean cloth.

With this cleaning method, rust, oily resinous dirt, etc. are removed. and the metal parts of the machines seem to be re-polished. There is no other way to clean them so well, not to mention the extreme cheapness of the method itself, which makes it quite suitable for the indicated purpose with respect to all kinds of machines, tools, and in general products made of steel and polished iron.

With force, the rolled bundle retains its shape. Prepared 5 nozzles marked P400, P500, P800, P1000, P1200. There are large transverse scratches. Shaft torque is highly dependent on speed.

Up to 12,000 rpm, the speed drops when pressed, and above 20,000 rpm, the skin wears out quickly. Sand perpendicular to the scratches until they disappear. Such a nozzle is quickly updated and provides the necessary pressure on the surface.

A lot of things for the home master in this Chinese store.

The worn and greasy part is cut off. The direction of grinding periodically changes to perpendicular. So the material is removed more efficiently and chaotic scratches are better removed. Increasing the paper number. In the process of grinding, the paper wears out, its aggressiveness decreases, and a large abrasive crumbles. Therefore, less pressure should be applied to the new paper so as not to get deep scratches. Coarse paste for fine grinding. 320 is all that was indicated on the package.

Before changing to a thinner paste, the polishing area must be cleaned of its residues. Another no name paste. The composition contains a dye. One can only guess about the type of abrasive. It is not necessary to do this, the paste is applied only to the nozzle. Noticeable quick sanding. Sanding is better.

Metal polishing is more than sanding with fine abrasives. There are also chemical processes (dissolution of oxide films by substances that are part of the pastes) and thermal (thermal softening of the material and smearing it over the metal). Before polishing, the surface must be cleaned of scratches, gradually reducing the size of the abrasive. Before moving on to finer sandpaper, make sure that all scratches are removed. Depending on the depth of the scratches, the number of sandpaper is selected, from which grinding will begin. If there is a medium paste GOI No. 3, sandpaper with a number greater than P1200 can be omitted. their grain size is comparable, and the sandpaper itself with a small grain size is quickly salted.

For polishing steel, the optimum nozzle pressure is 1-2 kg/cm^2 and peripheral speed is 30-35 m/s. Peripheral speed formula. V=(3.14* D* n)/60 (m/s); D-diameter of the nozzle (m); n-speed (rpm). In the case shown, V=(3.14*0.01*15000)/60=7.8 m/s. This is 4 times less than recommended. Those. it is possible to increase the diameter up to 4 cm without loss of quality. At the same time, it will quickly crumble from cotton wool, but leather or cotton threads will withstand it.

Polishing at a higher speed and pressure than recommended reduces the quality of the surface, but increases the amount of metal removed, so this can be used at the initial stage of polishing. To obtain a better polishing, the speed and pressure are reduced to values ​​lower than those recommended.

During the polishing process, the binders included in the paste melt and act as a lubricant in the process of cutting the material with an abrasive, and also remove heat from the surface. At the same time, the polishing nozzle itself heats up and the binder begins to penetrate deep into it, leaving the abrasive grains without lubrication and heat sink. After that, the grains, having lost the binder, fall off and leave scratches on the treated metal. For the same reason, the paste should not be applied to metal. The nozzle passing through the metal cannot capture all the material, and the captured grains of the abrasive are not held well enough, moreover, the grains themselves are not evenly distributed over it. Too much pasta isn't good either. It simply slides over the binder layer between the metal and the nozzle, and the abrasive grains float in the layer without coming into close contact with the surfaces.

Since the binder must melt for normal operation of the paste, such pastes will work only in a certain temperature range, when the binder has already melted, but is still thick enough to hold the abrasive grains on the nozzle. For most pastes, the range starts at 70 degrees Celsius. And it is for this reason that polishing by hand is extremely inefficient. For normal operation, this must be melted, add any liquid oil and mix. Conventional softening solvents are not suitable. quickly evaporate and the product thickens.

Source: youtube.be/lMjLMd1dY8Q

Matting and polishing aluminum

We have been working with manufacturers of metal products for a long time, and we know that the appearance of the product is very important. If we are talking O technical products, then everyone here is already accustomed to polishing, satin or matting the surface.
But sometimes our partners have to work with decor items. And sometimes the customer wants the surface to look unusual.
One of the options for such an unusual solution, we offer you below.
The so-called "muddy polishing".
This time we processed flat aluminum parts.
For aluminum one of the most convenient ways processing is an orbital sander. It allows you to get the most even and monotonous surface on such a soft and capricious metal.


For pre-grinding aluminum, we used our matting technology, only changed the number and graininess of the circles used:
Grinding wheels Velcro AO (aluminum oxide) d125, grit P180- the first step by which we remove all defects and level the surface.
Grinding wheels Velcro AO (aluminum oxide) d125, grit P220- decrease in roughness.
Grinding wheels Velcro AO (aluminum oxide) d125, grit P400- decrease in roughness.
Grinding wheels Velcro AO (aluminum oxide) d125, grit P600- final grinding.


After processing the OShM, the surface already becomes uniform and beautiful. But this time the task was to get something new.
It was decided to polish our workpiece from above using the same eccentric machine.
If you polish the surface with a conventional polishing angle grinder, it will be very difficult to achieve an ideal result. Such a process will take much more time.


Surface after P600.
It is better to use liquid polishing pastes for polishing with OSM, since hard paste is difficult to apply to the polishing wheel during orbital movement.
The polisher itself should also be used softer.
We recommend:
Polishing wheel Finesse-it d125 soft felt
Liquid polishing pastes G-Polish Pink
We apply the paste on the circle and proceed to polishing.


After polishing, the surface looks dirty and the gloss is almost invisible. This is because there is a lot of paste left on its surface.


To remove the remaining paste, use Viennese lime with a microfiber cloth:
Vienna lime
Cleaning cloth


Now the surface looks great.


Aluminum is a fairly soft metal. Therefore, to prevent aluminum from oxidizing and tarnishing, we varnished the product.
There are different ways to finish such a surface - you can grind to a finer grain or polish in two steps to get more gloss.
But that's a completely different story.

Polishing is the final process of manufacturing a part, carried out using various ways in order to remove the minimum layer of metal to achieve mirror shine surfaces. These are interrelated physical, chemical, electrical influences, the choice of which depends on the type of material, the tool used and the characteristics external environment. The required quality is achieved by replacing abrasives and methods of exposure. Polishing time depends on the initial quality of the metal.

GOST requirements for metal polishing

Requirements for the quality of metal and coatings are defined in GOST 9.301-86. Surfaces must be free of pits, pores, rust, cracks after grinding, scale, and burrs. There are no regulatory requirements for the degree of gloss.

At enterprises engaged in metal processing, input control of surfaces is carried out. If necessary, the following is carried out:

• treatment with compressed air containing an abrasive (steel shot) (rust and scale are removed);
• metal brushing to remove oxides and pickling sludge;
• degreasing heated in organic solvents (chlorinated carbons) to remove grease;
• degreasing in alkali solutions (removal of mineral oils);
• degreasing in electrolyte (electrochemical).

At home, surfaces are wiped with a solvent, treated with a file or a grinder with a disk with the appropriate grain size.

Metal polishing class

The polishing class is determined by the surface roughness (roughness in microns) of a particular part. The roughness corresponds to the area of ​​use. In total, there are 14 purity classes, which are indicated in the drawings by an equilateral triangle. Numerical values ​​of roughness after metal polishing are specified in GOST 2789-59.

Metal polishing class

Surface appearance	Irregularity height (up to mcr)	Class	Type of processing
Traces of processing are clearly visible			Turning, milling, planing
Processing marks are almost invisible		fourth	Semi-finishing
Processing marks are not visible			Fine turning, grinding
Surface with a mirror finish			Finishing polishing
		eleventh
		twelfth
		thirteenth
		fourteenth

In industry, special instruments are used to measure the height of irregularities: profilers and microscopes. At home, the roughness is determined "by eye".

Existing metal polishing methods

The most common ways to polish metal:

• mechanical (abrasive);
• chemical (pastes, solutions);
• electrochemical (in electrolytes);
• ultrasonic.

Mechanical polishing of metal can be dry or wet.

The process can be carried out:

• manually;
• in semi-automatic mode;
• automatically.

Important! With manual processing, you can monitor the process and influence the result. It is impossible to achieve high quality and productivity.

Semi-automatic is a special equipment and a qualified specialist. Processing is carried out on metal polishing machines, technological parameters are changed manually. With automatic processing in batch production, human participation is not required. The work is carried out very quickly and with high precision. The amount of scrap is minimized.

Hand polishing small parts at home. The paste is applied to a rag and rubbed on the surface in a circular motion. For large surfaces, grinders (grinders) or drills equipped with nozzles of various grain sizes are most often used.

Various attachments can be installed on the disc. If the nozzle is made of felt or fabric, it is moistened with paste. A professional tool is used in auto repair shops, as it allows you to process surfaces of sufficiently large sizes. In small metalworking enterprises, machines equipped with polishing belts or felt (cloth) circles are used.

Mechanical methods also include abrasive technology for polishing metal in vibrating drums filled with dry abrasive or solution. Rotation and vibration can quickly reduce roughness. If the method is dry, then the solution is replaced with oak or ash sawdust, pieces of felt or suede. If a solution is used, then in addition to polishing steel balls, alkali can be added to it (for example, a solution of laundry soap), which speeds up the process.

But mechanical polishing has a number of disadvantages:

• there is a possibility of the introduction of abrasives into the structure of the metal;
• high installation and resource costs;
• processing consists of several stages;
• the process is difficult to manage;
• required significant costs manual labor and time.

Important! Chemical polishing has a higher potential, especially when it comes to elements of decorative interior decoration made of various alloys or expensive metals.

When using this method, metal products are immersed in solutions of a certain temperature. During the passage of chemical reactions, the roughness melts within a few minutes. There is almost no manual labor, power tools and metal polishing devices are not required. The surface is processed uniformly, the configuration of the part does not matter.

But there are also disadvantages. Mirror gloss is not achieved (the surface is rather matte), the solution needs to be changed frequently, it is quite aggressive (most often it is an acid). Work can be carried out only in overalls, the room must be equipped with a high-quality ventilation system.

During electrochemical polishing, parts are also immersed in a solution, but a electricity. Since the surface is uneven, the oxide film is thicker in the micropits. The solution processes even parts of the surface with a thin layer of oxide faster. At the end of the process, the surface is perfectly smooth. Small time costs give an opportunity to increase productivity.

Flaw - high flow electricity. If the surface is rough, mechanical grinding is required. It is necessary to carefully monitor the quality and temperature of the solution, the current density. Solutions are created from acids, so safety regulations must be observed. To reduce costs, it is desirable to pre-process the material by mechanical means.

On large enterprises they try to automate and robotize polishing. This can be done using ultrasound, which increases productivity by 30 times and allows you not to purchase circles and pastes. Energy consumption is lower than when using a chemical or electrochemical method.

Metal polishing products

The technology of manual polishing of metal requires the purchase of equipment (drills, grinders) and various nozzles.

The main means for mechanically polishing metals are various pastes containing silicon, zirconium or titanium carbide, diamond chips, chromium oxide. Hard pastes must be diluted with oil. The costs are high, since the process consists of several stages, each of which requires different nozzles.

If a chemical or electrochemical method is used, large containers and acids are needed for the preparation of solutions, overalls. Nitric, hydrochloric, sulfuric, phosphoric acid, glycerin, benzyl alcohol are used. For a household, these are quite expensive purchases, so chemicals are used only in enterprises.

Metal polishing machines

All polishing machines are divided into 2 groups: with circles and tapes. Belts and circles consist of abrasives, the choice takes into account the requirements for surface roughness after processing. The equipment is semi-automatic or automatic. Automatic machines can become part of the lines used in mass production.

Any machine is equipped with a bed (platform) that does not change position during operation. An electric motor is mounted on the platform, which drives the shaft. You can work with grinding abrasives and circles. The sharpening angle is adjusted manually or automatically. Some designs are equipped with a water tank needed for cooling.

Available machines for processing raw materials (sheets of steel, aluminium, brass, profiles) and finished products:

• ship fittings;
• plumbing equipment;
• metal cornices and railings;
• door handles, parts of candlesticks;
• bicycle parts;
• tables and chairs;
• mufflers for motorcycles and cars.

The power of industrial models is 700-950 W, they are connected to a 220 V network. The rotational speed is 90-150 rpm. Adjustment is made depending on the characteristics of the material being processed and the format of the circle. At the first stages of processing, large circles are used, small ones are used for refinement. The package includes a cable and an extension cord. During operation, tools for measuring angles, stabilizers, pastes may be required.

Metal polishing is necessary to improve appearance metal products and giving them higher consumer qualities. Polishing gives metal products a decorative sheen and is also used in surface preparation for electroplating. The following methods of polishing metal surfaces are widely used in industry:

Disadvantages of traditional types of metal polishing

The first three of the listed methods of metal surface treatment have a number of application limitations. The main limitation for the series industrial enterprises is the impossibility of automation when using mechanical, chemical or electrochemical methods of surface treatment of products in large batches of mass production.

Difficulties in the use of traditional types of metal polishing have both economic and technological reasons. Economic difficulties are associated with the high cost of production robots and CNC machines. Technological reasons for the difficulties in using traditional types of metal finishing are associated with the difficulties of building a completely automated process production. The forced use of manual labor at the stage of polishing products, activating the surface or cleaning it does not allow for the smooth operation of industrial automated lines. Often, due to the use of outdated methods of metal processing, the production line takes the form of a conveyor, which significantly increases the cost of production and, as a result, negatively affects the competitiveness of manufactured products.

Comparison of types of metal polishing

	mechanical polishing	Chemical polishing	Electro-chemical polishing	Electrolyte-plasma polishing
Performance	Medium	Low	Medium	High
Geometry constraint	simple profile	Complex profile	Complex profile	Complex profile
Material change	Susceptibility to the introduction of foreign particles	Uneven processing, pickling	Poor processing of flat surfaces	Material hardening possible
Complexity of processing	Medium	Medium	High	Medium
Possibility of automation	No	No	Eat	Eat
Material costs	High	High	High	Low
Plant amortization period	25 years	5 years	20 years	25 years
Occupied production sq.	Malaya	Medium	Medium	Medium
Environmental friendliness	Low	Low	Low	High
fire hazard	Low	High	Medium	Low
Energy consumption	Average	Low	high	high
Qualification of employees	High	Medium	Medium	Medium

The widespread introduction into industry of more productive electrolytic-plasma polishing of metal will eventually make it possible to replace the toxic electrochemical processing method almost everywhere. Its advantages, in comparison with other methods of polishing surfaces, are high productivity and efficiency, environmental friendliness environment, high quality and speed of operations, low cost.

The electrolytic-plasma method of polishing surfaces is environmentally friendly and satisfies sanitary standards, for the purification of the spent electrolyte, special treatment facilities are not required.

Methods for polishing a metal surface by combining various methods and types of surface treatment

Often polishing is carried out on products without preliminary surface treatment with an unprepared, rather rough surface with a rough relief, which entails the need for long-term electrolytic-plasma treatment, which is accompanied by the removal of a significant metal layer, and leads to excessive energy consumption.

In addition, in the process of processing a rough branched surface, a phenomenon is observed that the current density in the first stage of processing is sometimes twice as high as in the final stage. This is due to the fact that the initial area of ​​the rough surface in contact with the electrolyte is apparently twice as large as that obtained as a result of processing.

In practice, it is better to polish products in two stages, at the first stage, cleaning and degreasing the surface, and at the second stage, polishing itself. Cleaning of parts before polishing is necessary because in the manufacture of metal products by casting, or during their heat treatment, even in neutral environments, it is not possible to completely avoid contact of the surface with an oxidizing environment (for example, air) in the area high temperatures when the surface oxidation of the metal occurs. For the purpose of cleaning before polishing, such types of surface treatment are used as:

1. tumbling
2. underwater grinding
3. hydroabrasive processing
4. iron sand treatment
5. corundum processing
6. sonication
7. chemical and electrical etching

Types of metal surface treatment after gas plasma cutting

Smoothing the surface roughness obtained after such a popular type of plasma metal processing as gas plasma cutting does not have to be done by cutting off the protrusions. Pre-treatment can be carried out by surface plastic deformation. In some cases, mechanical methods of surface treatment with pastes do not consist in cutting off the protrusions, but in kneading them, for which purpose the pastes contain special lubricants, chemically active, surfactants that soften the surface and fine oxide particles, for example, inert chromium oxide.

Polishing of metal products by electro-plasma method with preliminary preparation

To save energy, it is advisable to use the technology of electrolytic-plasma polishing in two stages, when at the first stage the rough surface relief is smoothed out using various energy-saving surface treatment methods, and then at the second stage finishing short-term electrolytic-plasma polishing is applied.

For example, when polishing parts made of stainless steel, which is ductile and quite soft, the following surface treatments can be applied in the first stage:

1. grinding under a layer of water with a waterproof sandpaper with a grain size of 50-80 microns
2. hard wire brushing
3. electroetching in a 10% oxalic acid solution at a voltage of 12 V for 5–10 minutes with a current density of up to 2 A/cm2
4. sandblasting with fine cast iron chips
5. bleaching etching in a solution of 25% sulfuric and 20% hydrochloric acid in a volume ratio of 3/1 at a temperature of 30–40°C for 3–5–10 minutes.

Subsequent electrolytic-plasma polishing of products can be carried out in a 5% aqueous solution of ammonium sulfate at a temperature of 80°C.

Methods of metal processing before electrolytic-plasma polishing

Methods for processing metal using stripping

If the original sample, the surface of which is pre-treated with a coarse sandpaper with a grain size of 500 microns, is polished to a mirror finish for 5-6 minutes with the removal of a metal layer of 0.05 mm, then the samples treated to a matte state with a sandpaper with a grain size of 50-80 microns are polished in two times faster in less than 3 minutes, and at the same time a layer of metal with a thickness of only 0.02-0.03 mm is removed. Energy savings when using pre-treatment of the surface with sandpaper is about 40%.

Types of metal processing using brushing

Pre-treatment with metal brushes of a roughly ground or chiseled surface is also very effective. Apparently, the surface relief during such processing is leveled due to plastic deformation of the metal, and partially due to brushing, i.e. abrasion, scratching metal. The oxide film is also removed, which prevents uniform polishing of the product in cases where it is made by welding or subjected to high-temperature heat treatment.

Metal processing methods using etching

Good results were obtained during chemical etching, especially of samples that were subjected to heat treatment, since in this case scale is formed on the steel, which is difficult to remove by electrolytic plasma treatment for 15 minutes or more. Etching of such specimens in solutions of sulfuric and hydrochloric acids creates a rough, scale-free surface without defects. Subsequent processing of the samples in ammonium sulfate at a voltage of 260 V for 4 minutes makes it possible to obtain a shiny surface.

There are many options for polishing a knife to a mirror finish. Some of them are aggressive, others are softer and more accurate. Polishing can be done with ordinary natural stones, wet and dry paper. The most careful work is carried out with the help of special pastes of domestic and foreign production.

Polishing by hand

Masters from all over the world in the past did not have specialized equipment, but they performed their work with high quality. But how to polish a knife without special equipment? After heat treatment, the craftsmen used natural abrasive materials (such as stone or metal fixtures).

Polishing by hand helps to achieve a perfectly smooth surface. In this way, you can get the correct shape of the blade. Even using a special polishing and grinding device, it is not always possible to achieve a similar effect. It is believed that hand polishing is the final processing of the knife.

How to polish a knife at home correctly using the manual method? Before moving on to manual processing, it is necessary to polish the knife on a tape, the grain size of which should not be less than 320. First of all, scratches are removed with sandpaper. They may appear on the surface of the product after machining.

Features of emery processing

How to polish a knife to a shine with sandpaper? The first step is to polish at an angle of 90 degrees. In this case, irregularities may appear on the surface of the knife. This may be due to the accumulation of grain on the surface. Sometimes the roughness cannot be removed with paper with little abrasiveness. In this case, you need to go back to coarser material.

To carry out the work as efficiently and carefully as possible, it is necessary to provide high-quality lighting, and the whole process must be carried out under a magnifying glass. When all the shortcomings are eliminated, you can go back to standard processing.

Sandpaper can be used in the polishing process different types. The main thing is that the transition between graininess should be insignificant. First, the material is processed with a grain size of 600, then it is increased to 800. You can stop, or you can continue polishing with a material with an indicator of 2000.

abrasive stones

How to polish a knife blade with a stone? Abrasive materials of this type have different grain sizes. The most popular indicators are 320, 400 and 600. To properly level the knife, experts recommend using Indian bench stones.

Such a simple device is still used today, although it was first used in the Stone Age, to remove excess material from weapons. At that time, not only stones were used, but also sand and soil.

For polishing, only those stones were used that were harder than a knife in their structure. Some masters prefer a square shape, while others like a round one. The most popular polishing stone is sandstone.

How to use stones correctly?

When polishing, coarse and thin stones are used. Rough material has a grain size of 80, and fine material has a grain size of 15. You can examine the structure of the stone in detail under a microscope. How to polish a knife in this way? A rough stone is used to remove the scratches that most often appear on a knife after a file. Another type of stone is usually applied before heat treatment. So that the surface of the stone does not clog, it must be periodically moistened with water.

To understand how to polish a knife to a mirror finish, you need to pay attention to Arkansas stones. Their grain size can reach 1000. This material ideal for finishing. If polishing is just beginning, it is better not to use such stones, as they work slowly. You can achieve a mirror shine with the help of Japanese wet stones. In addition, on sale you can find not only natural, but also quite high-quality artificial stones.

Quick polishing by hand

You can also polish the knife by hand. Movement must be done along the blade. It is this tactic that helps to get the job done as quickly as possible. Often, for these purposes, a two-sided

To polish the blade of a knife is obtained due to rapid friction. This method has many disadvantages. The surface of the knife turns out to be imperfect, rough waviness and scratches can be seen on it.

Such shortcomings can be eliminated, but for this all scratches must have one direction. After rough processing, it is necessary to prepare a small piece of leather and a special polishing composition, with the help of which the finishing process is carried out.

Application of dry and wet paper

Polishing works are carried out both with dry and wet paper. The material should be slightly damp so that it does not deteriorate or become greasy during the polishing process. For certain types of work, only dry paper should be used.

How to polish a knife at home with paper? To do this, it is recommended to purchase a whole set, which usually consists of fifty sheets. This option is considered the most economical. It should be borne in mind that waterproof material is more durable than non-water resistant. For polishing metal products, paper treated with crushed silicon carbide is excellent.

To work with the material was convenient, you must proceed as follows:

• paper is folded in half lengthwise;
• the material is fixed with clamps to a small steel plate;
• if you fold the paper in half and attach it to the plate, it will not slip off during operation.

Previously, experts recommend making small templates and blanks. If the master needs to process the area near the handle, small strips are not folded, but applied across the entire width. To prevent the tape from tearing during the polishing process, the material is pasted over with masking tape on the back side.

Mirror Processing

Knives of any type look amazing when they have a perfect mirror surface. But how to polish a knife blade at home so that it has such an excellent surface? Each master uses his own polishing methods. Whatever method is used, the ideal surface of the knife speaks of a high level of craftsmanship.

Often, to achieve an ideal surface, the product is first polished by hand to a grit of 800, and then a special grinding wheel is used. Such processing is necessary in order to remove all irregularities and prepare the knife for the final mirror polishing.

Grinding wheels must be handled with care. Too much speed can damage the product. The grinding wheel in most cases should have a soft surface. For some types of work use solid. It is also dangerous to work with loose polishing wheels. They have one unpleasant feature - they often capture blades and some other parts of the product.

Security measures

Many people think about how to polish a knife at home safely. The most important condition is not to install the polishing machine directly on the desktop. The fact is that in the process of work, the polishing wheel often captures the blade, which can bounce and harm the master.

Experienced craftsmen, who often polish and grind knives, additionally install special protections on the polishing wheels. In this case, the residual material in the form of polishing compound and dust will fly to the floor, and not to the master.

Using GOI paste

This method is well known to craftsmen who are engaged in the manufacture of knives. How to polish a knife with GOI paste? To do this, you must select the appropriate type of polishing material, which depends on the type of metal. In addition, there are a few polishing rules to keep in mind.

GOI paste has been used for over a hundred years. With its help, metal, plastic, ceramic and even glass products are polished. Previously, the paste was presented in green and was made from chromium oxide. However, this substance was recognized as poisonous, and at the moment the paste is made from aluminum oxide. The paste is presented in red and white.

Types of pasta

Previously, there was only one type for sale. But now experts have much more choice. Paste is produced with different abrasiveness:

• No. 4 - it is used specifically for rough work that is carried out at the initial stage of polishing;
• No. 3 - helps to achieve a matte finish;
• No. 2 and No. 1 are used for finishing.

Green paste is sometimes still found on sale, but it is difficult to find it. Previously, such a polish was produced both in liquid form and in the form of bars. In terms of effectiveness, the two types of paste are identical. Green has one advantage - low cost.

Preparing for polishing

Before you understand how to polish a knife, you need to familiarize yourself with the preparation for this process. It must be remembered that the paste has many particles, thanks to which polishing is carried out. Sometimes they can accumulate and spoil the product. To prevent this from happening, you need to take a small amount of the substance and rub it on an old piece of metal. In this way, large pieces of grain can be broken, otherwise the surface of the knife will not be polished, but scratched.

First you need to take a soft cloth and lightly moisten it with gasoline. In this case, the fabric should be as soft as possible. Flannel is perfect for this purpose. Often the paste is applied directly to the buffing pad. It cannot be applied to the product itself. The knife should be lightly lubricated with special oil.

How to use the paste?

So how to polish a knife with GOI? When the fabric and paste are ready, you can proceed to the main steps. You just need to rub the product with this composition. Do not press hard on the surface of the knife. Otherwise, there will be small scratches on it.

For the same reasons, it is not recommended to make very sharp movements. Work is completed when the surface of the product is perfectly smooth. During work, from time to time you need to stop and apply a little industrial oil to the knife.

If the surface of the knife has many flaws, in this case you will need to purchase several types of paste. First, the treatment is carried out with paste No. 4, thanks to which deep scratches are removed. After that, go to number 3, and then to paste number 2 and 1. The last type of paste helps to finish grinding and achieve a mirror surface.

At the end of the work, you need to rinse the knife in running water. Experts recommend using not water for this, but kerosene, which can be purchased at a pharmacy. The knife must be thoroughly dried. Some masters additionally cover the surface of the knife with zaponlak. This substance helps prevent oxidation of the material. The last stage is polishing the product with natural leather.

Knife handle processing

If everything is clear with the blade, then how to polish the knife handle? In this case, you need to act with extreme caution. For these purposes, use sandpaper of the finest grit. Be careful not to damage the handle. This is a rather fragile item.

Now about the material. Which is better to choose for this operation? GOI paste will be an excellent polishing agent. But which type to choose for processing the handle of a knife? In this case, you need to use paste number 1 and 2. To make the handle shiny, it needs to be polished with a small piece of leather.

If the handle is made of wood, it is necessary to additionally impregnate. This will help to keep its original appearance for a long time. Usually impregnation is carried out with the help of ordinary or special oil, which is sold in an artist's store. In addition, you can simply cover the handle with a protective varnish.

Conclusion

So, we figured out how to properly polish a knife. As you can see, there are many ways to do this. The main thing is to properly prepare for the procedure and follow the recommendations of specialists. This is the only way to achieve the desired result.