The essence of the process of chemical milling is the controlled removal of material from the surface of the workpiece by dissolving it in the etchant due to a chemical reaction. Sections of the workpiece that are not subject to dissolution are covered with a protective layer of chemically resistant material.

The removal rate of many materials is up to 0.1 mm/min.

Process Benefits:

high productivity and quality of processing,

· the possibility of obtaining parts of complex configuration, both small and large thickness (0.1-50) mm;

low energy costs (mainly chemical energy is used);

short cycle of preparation of production and simplicity of its automation;

· non-waste due to the regeneration of the process products.

During processing, material removal can be carried out from the entire surface of the workpiece, to various depths or to the entire thickness of the part (through milling). Chemical milling includes the following main stages: preparation of the workpiece surface; applying a protective layer of the picture; chemical etching; removal of the protective layer and quality control of products (see fig. 3.1).

Surface preparation is cleaning it from organic and inorganic substances, for example, using electrochemical degreasing. The degree of purification is determined by the requirements for subsequent operations.

The application of the protective layer of the pattern is carried out by the following methods: manual and mechanized engraving on the overcast (lacquer, wax) layer, xerography, screen printing, offset printing, and photochemical printing.

In instrumentation, the most widely used method is photochemical printing, which provides small sizes of products and high accuracy. In this case, to obtain a protective layer of a given configuration, a photomask is used (an enlarged photocopy of the part on a transparent material). As a protective layer, liquid and film photoresists with photosensitivity are used. Liquid, the most mastered in the industry, require high quality cleaning of the surface of the workpieces. To apply them to the surface, one of the methods is used: immersion, watering, spraying, centrifugation, rolling, spraying in an electrostatic field. The choice of method depends on the type of production (continuous application or on individual blanks); requirements for the thickness and uniformity of the formed film, which determine the accuracy of the dimensions of the pattern and the protective properties of the resist.

Rice. 3.1. General scheme of the technological process of chemical milling.

Photochemical printing of a protective pattern, in addition to the operation of applying a photoresist and drying it, includes the operations of exposing the photoresist layer through a photomask, developing the pattern, and tanning the protective layer. During development, certain areas of the photoresist layer dissolve and are removed from the surface of the workpiece. The remaining photoresist layer in the form of a pattern defined by a photomask, after additional heat treatment - tanning - serves as a protective layer during the subsequent chemical etching operation.

The chemical pickling operation determines the final quality and yield of the product. The etching process proceeds not only perpendicular to the surface of the workpiece, but also sideways (under the protective layer), which reduces the accuracy of processing. The amount of etching is estimated through the etching factor, which is equal to , where H tr is the depth of etching, e is the amount of etching. The dissolution rate is determined by the properties of the treated metal, the composition of the etching solution, its temperature, the method of supplying the solution to the surface, the conditions for removing the reaction products, and maintaining the etching properties of the solution. Timely cessation of the dissolution reaction ensures the specified accuracy of processing, which is approximately 10% of the depth of processing (etching).

Currently, etchants based on salts with an amine, an oxidizing agent, are widely used, among which chlorine, oxygen compounds of chlorine, dichromate, sulfate, nitrate, hydrogen peroxide, and fluorine are most often used. For copper and its alloys, covar, steel and other alloys, solutions of ferric chloride (FeCl 3) with a concentration of 28 to 40% (weight) and a temperature in the range of (20 - 50) C, which provide a dissolution rate of (20 - 50) µm/min.

Among the known etching methods, there are immersion of the workpiece in a calm solution; in a stirred solution; spraying solution; solution spraying; jet etching (horizontal or vertical). The best processing accuracy is provided by jet etching, which consists in the fact that the etching solution is supplied under pressure through nozzles to the surface of the workpiece in the form of jets.

Quality control of parts includes visual inspection of their surface and measurement of individual elements.

The process of chemical milling is most beneficial in the manufacture of flat parts of complex configuration, which in some cases can also be obtained by mechanical stamping. Practice has established that when processing batches of parts up to 100 thousand, chemical milling is more profitable, and more than 100 thousand - stamping. With a very complex configuration of parts, when it is impossible to manufacture a stamp, only chemical milling is used. It should be taken into account that the process of chemical milling does not allow the production of parts with sharp or right angles. The radius of rounding of the inner corner must be at least half the thickness of the workpiece S, and the outer corner - more than 1/3 S, the diameter of the holes and the width of the grooves of the parts must be more than 2 S.

The method has found wide application in electronics, radio engineering, electrical engineering and other industries in the production of printed circuit boards, integrated circuits, in the manufacture of various flat parts with a complex configuration (flat springs, raster masks for kinescopes of color TVs, masks with a pattern of circuits used in thermal spraying processes , nets for razors, centrifuges and other parts).

Electrochemistry in a glass

Processes of electrochemical processing of metals are used in all branches of industry. With their help, you can perform operations such as drilling, turning, grinding or polishing, milling parts of the most complex configurations, and even remove burrs. In this case, the essence of the processes of electrochemical dimensional processing is the anodic dissolution of the metal during electrolysis with the regular removal of the resulting waste. And therefore - and this is the most valuable - for the processes of electrochemical "cutting" there are practically no hard-to-cut metals.

All these advantages of electrochemical processing processes can be successfully used at home to perform many interesting and useful jobs. For example, with their help, it is possible to cut an elastic plate from a razor blade in 20-30 minutes, cut a complex-shaped hole in a thin sheet of metal, and carve a spiral groove on a round rod (Fig. 1). To perform all these works, it is enough to have an AC rectifier that gives an output voltage of 6-10 volts, or a rectifier for micromotors of 6 volts, or, finally, a set of 2-3 batteries for a flashlight. Pieces of wire, metal, glue and other auxiliary materials can be found in any home workshop.

Milling.

If in some workpiece you need to make a recess of a complex configuration - for example, cut out the apartment number (Fig. 2), then for this you need to take a sheet of drawing paper and draw on it a life-size contour of the recess that you want to get. Then, with a razor blade or scissors, cut and remove the drawn outline, and cut the sheet in accordance with the shape and size of the workpiece. Glue the mask template (1) obtained in this way with rubber glue or BF-88 glue onto the surface of the workpiece (2), attach the wire from the positive pole of the rectifier or a set of batteries to the workpiece and apply 1-2 layers to all its surfaces remaining without insulation any varnish or nitro paint. It's a good idea to varnish or paint the mask template itself. After allowing the coating to dry, lower the workpiece into a glass with a concentrated solution of common salt, place a cathode plate (3) of any metal opposite the mask template and connect it to the negative pole of the rectifier or current source.

As soon as the current is turned on, the process of electrochemical dissolution of the metal inside the contour of the mask template will begin. But after some time, the intensity of the process will decrease, which can be seen from the decrease in the number of bubbles released on the cathode (3). This means that an insulating layer of process waste has formed on the treated surface. To remove them and at the same time measure the depth of the recess, the part must be removed from the glass and, trying not to damage the mask template, clean off the loose layer of waste from the surface to be treated with a small hard brush. After that, periodically removing the part to control the dimensions and remove waste, the process can be continued until the depth of the recess reaches the required value. And when the processing is completed, having removed the insulation and mask template, the part must be washed with water and lubricated with oil to prevent corrosion.

Stamping and engraving.

When a complex hole needs to be made in a thin sheet of metal, the principles of electrochemical machining remain the same as for milling. The only subtlety is that in order for the edges of the hole to be even, the mask template (1) must be glued onto the workpiece from both sides. To do this, the contours of the mask template (1) should be cut out in a sheet of paper folded in half and, sticking the template on the workpiece (2), orient it along one of its sides (Fig. 3). And besides, in order to speed up processing and ensure uniform removal of metal from both sides, it is advisable to bend the cathode plate (3) in the form of the letter "U" and place the workpiece to be processed into it.

For the manufacture of sheet steel - for example, from a razor blade blade - parts of any profile are done somewhat differently. The profile of the part itself (1) is cut out of paper and glued to the workpiece (2) (Fig. 4). Then the entire opposite side of the steel sheet is varnished, and on the side of the template, varnish insulation is applied so that it does not adjoin the template. And only in one place the applied insulation needs to be brought to the template with a narrow jumper (3) - otherwise the dissolution of uninsulated surfaces around the template may end before the contour of the part is formed. To obtain more accurate details, two templates can be cut out, glued to the workpiece on both sides and processed in a U-shaped cathode. In similar ways, you can make various inscriptions on metal, both convex and "depressed".

Threading and spiral grooves.

One of the varieties of the milling process is electrochemical cutting of spiral grooves and threads. This method can be useful for making at home, for example, wood screws or twist drills. When cutting a thread on a screw (Fig. 5), as a mask template (1), you need to take a thin rubber cord of square section 1x1 mm, wind it in a spiral on a cylindrical workpiece (2) with tension and fasten its ends with threads (3). And then those surfaces of the workpiece that are not subject to etching, isolate with varnish. As a result of electrochemical processing, a spiral thread cavity is formed on the workpiece between the turns of rubber. Now you need to sharpen or, more precisely, make that end of the workpiece conical, which will serve as the sting of the screw entering the tree. To do this, the workpiece must be removed from the bath, remove the rubber from it and dry it. And then, varnishing its surface in such a way that only the first 2-3 threads of the thread remain open, the workpiece is returned to the bath and the electrochemical treatment is continued for some more time.

To make a twist drill at home, as a mask template (1), you need to take three rubber cords of the same section and wind them onto a heat-treated cylindrical workpiece (2), but already in two passes (Fig. 6). Then, the surfaces of the workpiece that are not subject to processing, and for reliability, the rubber cords must also be varnished and, lowering the part into a glass-bath, electrochemical milling of the drill grooves to the desired depth should be carried out. Now these grooves need to be widened to form the so-called "back" of the drill (3). To do this, two out of three cords are removed from each strip of rubber insulation, and electrochemical milling continues for some more time. After that, removing the remaining insulation and sharpening the lead, you will get an excellent twist drill.

I am writing my diploma. I am new to Inventor. There is not enough time, who can help, please help) There is a beam welded from sheets 10 mm thick. The material of the sheets, as well as the welding material, are set using Semantic 2015. Dependencies on the edges, because in these sections, the beam is welded to the longitudinal beams (Figure 1).Loads, then Force applied - 500 N. The result is somehow strange.A 100 mm thick sheet of high-strength steel bent, as shown in Figure 2, 3. Reduced the force to 50 N, the picture is the same.What could be the reason?

Let's go in order. I agree with clause 3 of Article 1358. It clearly follows from this clause that a Utility Model (foreign patent) is recognized as used in a product (in your product) if it uses at least one feature from an independent claim of someone else's patent. This only feature used can only be a distinctive feature, since Article 1358 of the Civil Code refers to EVERY feature of an independent claim. "An independent claim must contain the necessary features: - to implement the purpose of the invention (utility model), - to achieve the technical result indicated in the description; The combination of features of an independent claim must provide patentability to the object of the invention or utility model"

It looks like it. element damping is just from combos. Examples are usually associated with either rotor dynamics or FSI analysis using acoustic elements. Or do you shake the containment? Well, there are water tanks))) they can be modeled with acoustic elements. Although it's fleas, of course. g - constant structural damping assign different g to different materials. and why Rayleigh damping is not suitable? well, except that you don't know the right alpha and beta. an approach with the creation of a FE model is used. In the FE model, there can be different objects such as combi14 or simply materials with damping. To assemble the matrix from the FE model is the task of the program. Our task is to assemble the FE model and set up the program correctly. Pushing your objects into its matrices after the program has formulated the matrix is ​​unproductive and does not correspond to the popular approach. A conversation about modal coordinates, apparently, is a conversation about solving by the method of superposition of harmonic or transient analysis. But it is not exactly)

Let's go in order. I think you agree with paragraph 3 of Article 1358. Yes? It clearly follows from this paragraph that if at least one feature from the independent claim is not used, then the patent is not used in the object. Do you agree? This only unused feature can be both a distinctive feature and a restrictive one, since Article 1358 of the Civil Code refers to EVERY feature of an independent claim. That's actually all I wanted to say.

Ratcheting is not stabilization, but the accumulation of deformation from cycle to cycle. but the reverse process is also possible - after all, stabilization and stretching of the hysteresis into a straight line. He even, perhaps, more often. How exactly a particular material will behave under specific conditions is another question. that's it. only in special cases. Let's say we stretch the material. and let us assume that our material is such that at a sufficiently large deformation the Bauschinger effect ceases to be observed. how can it be, for example ... but we have exceeded the yield strength twice. If the Bauschinger effect worked, then during unloading and subsequent compression, the material would begin to plastically deform immediately. And if at the stage of stretching the yield strength was exceeded by a factor of three, then the material would flow in compression without being loaded yet. This leads us to the fact that the yield surface is not rigid, but has the ability to deform in the region of large deformations. But the adherents of isotropic hardening go further. And let's, so that the above crap does not work out, as the fluidity surface shifts, we will also expand it. Then, with a large tension and subsequent unloading and compression, it is possible to choose such parameters in order to fall into a separate particular experiment or several experiments. But, by applying isotropic hardening, we expand the surface not only in one direction, but also in the perpendicular one. If you look at the space of stresses, then let's say tension / compression - it was about sigma1, then perpendicular - sigma 2 or sigma3. And now this is categorically false. That is, for complex loading trajectories, this will not work. Therefore, the combination with isoporny hardening is a dead end. It does not exist in nature, it was simply easier to program it at the dawn of the development of FEM for problems with one-sided plastic deformation and a simple loading path. As a bonus to those who read to the end. There is also combined hardening, by the way, but with good results.

I m polish

METHOD OF ELECTROLYTIC MILLING

INTERNAL CONNECTING WINDOWS

CHANNELS IN PARTS FROM ALUMINUM AND ITS ALLOYS

Claimed February 8, 1957. No. 566488 n Committee for Inventions and Discoveries of the USSR Sonnet of Ministers

The invention relates to methods for electrolytic milling connecting windows of internal channels in parts made of aluminum and its alloys.

Known methods of this kind do not make it possible to perform internal connection of channels in hard-to-reach places. According to the invention, to obtain such channels, copper tubes are used, which serve to supply and drain electrolyte and are a cathode. As an electrolyte, a solution of neutral salt is used, for example, a solution of industrial sodium chloride.

The proposed method of electrolytic milling is illustrated in the drawing.

In a product 1 provided with two or more channels 2, it is required to make a channel 3 connecting the first two channels. To do this, an insulating-sealing tube 4 is inserted into one of the channels 2, inside which 1 copper tubes 5 and 6 are located, which served to supply and drain electrolyte. The product is connected to the positive pole of the current source and serves as an anode, and copper tubes - to the negative pole and serve as a cathode. Electrolyte is continuously pumped through tube 5 by a pump. Under the action of the current and the mechanical action of the electrolyte jet, the anodic dissolution of the metal of the product occurs in the direction of the electrolyte jet. Through tube 6, the electrolyte enters the collector and then again into the supply pump.

For the processing of aluminum products, a 10 - 20% -HblH solution of technical table salt is used as an electrolyte. The current density should be equal to 10"

Current source voltage 15V

25th c. With the selection of appropriate electrolytes, the method can be applied to the processing of other metals. No. 110679

Subject of invention

Rep. editor L. G. Golaidsky

Standardgiz. Signed to the stove January 14, 1958 Volume O, I25 and. l. Circulation 85O, ceiz 28 iop.

Printing house of the Committee for Inventions and Discoveries under the Council of the USSR Ministry of Construction

Moscow, Neglinnaya, 23. Zak. 1980

1. A method for electrolytic milling of connecting windows of internal channels in parts made of aluminum and its alloys, consisting in the fact that an electrolyte jet is directed to the surface to be treated, and the product and the electrolyte jet are connected to a direct current source, from and yc t c M, that, in order to create the possibility of making holes in hard-to-reach places, copper tubes connected to the negative pole of the current source are used to supply and drain the electrolyte.

2. Method according to and. 1, characterized in that a solution of industrial common salt is used as an electrolyte.

Similar patents:

The invention relates to equipment for electrochemical analysis and can be used as a sensor in the polarographic equipment

The invention relates to the field of electroplating and can be used in the electrical industry, in instrumentation and for decorative purposes in the production of consumer goods. The method is characterized by the fact that the anode made of silver and silver alloys and the metal cathode are immersed in an electrolytic bath and a voltage of 280-370 V is applied to them at an anode current density of 0.4-0.8 A/cm2 and at a temperature of an aqueous electrolyte solution of 20-40 °C, while an aqueous solution containing ammonium chloride, ammonium citrate and tartaric acid is used as an electrolyte in the following ratio of components, wt.%: ammonium chloride 3-10; ammonium citrate 2-6; tartaric acid 1-3; water the rest. The technical result consists in polishing a silver or silver-containing part - an anode and obtaining silver oxide on the cathode surface.

The invention relates to the field of electrochemical processing of non-ferrous metal blanks, and in particular to an aqueous electrolyte solution used for processing. The electrolyte solution contains citric acid with a concentration in the range from 1.665 g/l to 982 g/l, ammonium hydrofluoride with a concentration from 2 g/l to 360 g/l and not more than 3.35 g/l of a strong acid. Surface treatment of the workpiece includes exposing the surface to an aqueous electrolyte bath, adjusting the temperature of the bath to less than or equal to 85°C, connecting the workpiece to the anode of a DC power supply, and immersing the cathode of the DC power supply in the bath and passing a current of less than 255,000 amps through the bath for square meter. EFFECT: invention makes it possible to use an aqueous electrolyte solution for processing various non-ferrous metals, while the electrolyte is environmentally friendly and does not create hazardous waste. 6 n. and 23 z.p. f-ly, 12 ill., 9 tab.

The invention relates to the field of electrochemical methods for processing metal surfaces, including decorative processing. The method includes treatment of the silver surface in an aqueous solution of sodium thiosulfate Na2S2O3×5H2O - 790 g/l at a temperature of 35±2 °C using pulsed unipolar and bipolar rectangular currents with the following amplitude-time parameters: timp=0.1-10.0 ms , tneg.pulse=0.1-10.0 ms, delay duration of the current pulse of negative polarity tp=0.1-10.0 ms, tpause=0.1-10.0 ms, amplitude current density in the pulse of positive polarity iimp =0-5 A/cm2, amplitude current density in a pulse of negative polarity iotr.imp=0-5 A/cm2 and processing time 0.5-15.0 minutes, and the current is unipolar when iotr.imp=0. EFFECT: formation of passive decorative films resistant to external environmental influences on the surface of 925 silver alloy. 3 ill.

Processes of electrochemical processing of metals are confidently gaining their way in all industries. With their help, you can perform operations such as drilling, turning, grinding or polishing, milling parts of the most complex configurations, and even remove burrs. In this case, the essence of the processes of electrochemical dimensional processing is the anodic dissolution of the metal during electrolysis with the regular removal of the resulting waste. And therefore - and this is the most valuable - for the processes of electrochemical "cutting" there are practically no hard-to-cut metals.

All these advantages of electrochemical processing processes can be successfully used at home to perform many interesting and useful jobs. For example, they can be used to cut an elastic plate from a razor blade in 20-30 minutes, cut a hole of complex shape in a thin sheet of metal, and carve a spiral groove on a round rod. To do all this work, it is enough to have an AC rectifier that outputs a voltage of 6-10 volts, or a 6-volt micromotor rectifier, which can be purchased at children's toy stores, or, finally, a set of 2-3 batteries for a flashlight. Pieces of wire, metal, glue and other auxiliary materials, probably, can be found in any home workshop.

Milling

If in any workpiece you need to make a recess of a complex configuration - for example, cut out the apartment number (diagram below), then for this you need to take a sheet of drawing paper and draw on it a life-size outline of the recess that you want to get. Then, with a razor blade or scissors, cut and remove the drawn outline, and cut the sheet in accordance with the shape and size of the workpiece.

Glue the template-mask 1 obtained in this way with rubber glue or glue on the surface of the workpiece 2, attach the wire from the positive pole of the rectifier or a set of batteries to the workpiece and apply 1-2 layers of any varnish or nitro paint to all its surfaces remaining without insulation. It is not bad to varnish or paint the mask template itself. After allowing the coating to dry, lower the workpiece into a glass with a concentrated solution of common salt, place a cathode plate 3 of any metal opposite the mask template and connect it to the negative pole of the rectifier or current source.

As soon as the current is turned on, the process of electrochemical dissolution of the metal inside the contour of the mask template will begin. But after some time, the intensity of the process will decrease, which can be seen from the decrease in the number of bubbles released on the cathode 3. This means that an insulating layer of process waste has formed on the treated surface. To remove them and at the same time measure the depth of the recess, the part must be removed from the glass and, trying not to damage the mask template, clean off the loose layer of waste from the surface to be treated with a small hard brush. After that, periodically removing the part to control the dimensions and remove waste, the process can be continued until the depth of the recess reaches the required value. And when the processing is completed, having removed the insulation and mask template, the part must be washed with water and lubricated with oil to prevent corrosion.

Stamping and engraving

When a complex hole needs to be made in a thin sheet of metal, the principles of electrochemical machining remain the same as for milling.

The subtlety lies only in the fact that in order for the edges of the hole to turn out to be even, the template - mask 1 must be glued to the workpiece from both sides. To do this, the contours of the template-mask 1 should be cut out in a sheet of paper folded in half and, sticking the template on the workpiece 2, orient it along one of its sides (diagram above). And besides, in order to speed up processing and ensure uniform removal of metal from both sides, it is advisable to bend the cathode plate 3 in the form of the letter “U” and place the workpiece to be processed into it.

For the manufacture of sheet steel - for example, from a razor blade blade - parts of any profile are treated somewhat differently. The profile of part 1 itself is cut out of paper and glued to workpiece 2 (diagram below).

Then the entire opposite side of the steel sheet is varnished, and on the side of the template, varnish insulation is applied so that it does not adjoin the template. And only in one place the applied insulation needs to be brought to the template with a narrow jumper 3 - otherwise the dissolution of non-insulated surfaces around the template may end before the contour of the part is formed. To obtain more accurate details, two templates can be cut out, glued to the workpiece on both sides and processed in a U-shaped cathode. In similar ways, various inscriptions can be made on metal, both convex and “depressed”.

Threading and spiral grooving

One of the varieties of the milling process is electrochemical cutting of spiral grooves and threads. This method can be useful for making at home, for example, wood screws or twist drills. When cutting a thread on a screw (diagram below), as a mask template 1, you need to take a thin rubber cord of square section 1X1 mm, wind it in a spiral on a cylindrical workpiece 2 with tension and fasten its ends with threads 3. And then those surfaces of the workpiece that are not subject to etching, insulate with varnish.

As a result of electrochemical processing, a spiral thread cavity is formed on the workpiece between the turns of rubber. Now you need to sharpen or, more precisely, make the end of the workpiece conical, which will serve as the inlet. wood screw sting. To do this, the workpiece must be removed from the bath, remove the rubber from it and dry it. And then, varnishing its surface in such a way that only the first 2-3 threads of the thread remain open, the workpiece is returned to the bath and the electrochemical treatment is continued for some more time.

To make a twist drill at home, as a mask template 1, you need to take three rubber cords of the same section and wind them onto a heat-treated cylindrical workpiece 2, but already in two passes (diagram above). Then, the surfaces of the workpiece that are not subject to processing, and for reliability, the rubber cords must also be varnished and, lowering the part into a glass-bath, electrochemical milling of the drill grooves to the desired depth should be carried out. Now these grooves need to be expanded to form the so-called “back” of drill 3. To do this, two out of three cords are removed from each rubber insulation strip, and electrochemical milling continues for some more time. After that, removing the remaining insulation and sharpening the lead, you will get an excellent twist drill.

grinding

To grind the surfaces of cylindrical parts by electrochemistry, in addition to traditional equipment, you must have a small electric motor or drill.

Having previously isolated the surfaces of the part that cannot be processed with a pack, mount it on the shaft of the electric motor 1, install the engine vertically on some bracket and lower the end of the part 2 to be machined into the electrolyte bath (diagram above). Power supply of the anode part. 2 current in this case, it is best to "organize" a sliding contact going to the motor shaft, and make cathode 3 flat, equal in length to the treated surface. Now it remains to turn on the electric motor and power the bath. With the beginning of the process, the darkening of the surface will begin - the formation of waste. To obtain the correct cylindrical shape of the treated surface, these wastes must be continuously removed. It is convenient to do this with a toothbrush with a bristle shortened for rigidity, which, pressed against the part, should be moved steadily up and down. Periodically removing the part for measuring the diameter, in this way it is possible to obtain a surface with X7i workmanship and dimensional accuracy of the 2nd class.

Polishing

In order to polish any steel surface, prepare two wooden "kolobashki" 1 measuring 40X40 millimeters: one for rough and the second for fine polishing (diagram below).

Fix on them the plates of tin plate 2 bent at an angle, which play the role of a cathode, so that their position can be adjusted in height. To debug the polishing process, you need to take workpiece 3, connect it to the positive pole of the current source and place it in a bath with electrolyte in such a way that the level of the solution lies slightly above the horizontal part of cathode 2. bath salt solution, remove and pour a pinch of fine abrasive powder on it. Now, turning on the current, start polishing the part in a circular motion. In this case, it may happen that the electrochemical dissolution will be faster than the process of removing waste by the abrasive. To eliminate this discrepancy, raise the cathode plate higher and the dissolution rate will decrease. After polishing the entire surface with the first “bowl”, change the electrolyte solution to a clean one, wash the part from the abrasive and, using the second “bowl”, proceed to fine polishing, which should be done either without abrasive at all, or using tooth powder instead. With some training in this way on the details, you can get a mirror surface two to three times faster than mechanical polishing.

"Frost" on tinplate

Take an empty can of food or just a piece of tinplate and connect it to the wire from the positive pole of the rectifier. And connect any metal rod to the other pole, having previously made a cotton swab at its lower end. If now this kind of "shaving brush" is dipped into a solution of common salt and then slowly driven over the surface of the tin, then amazing things will happen to it. In those places where you brushed 2-3 times, sparkling crystals of “frost” appear - the crystalline structure of the tin coating will come to light. If you continue the process, then gray islands of waste will soon appear on the metal, firmly associated with the metal. And in the future, the entire surface of the tin will become spotty gray, with a characteristic bizarre pattern.

To obtain various decorative patterns on the metal, you can try using solutions of different salts or acids. So, for example, if instead of a solution of table salt we take a one percent solution of sulfuric acid, then the “manifesting” crystals will acquire a brown tint. If a tin plate is sprinkled with tooth powder, then the “frost” pattern will become more contrasting, with a milky gray tint. By preheating individual parts of the tin piece until the tin melts locally and quickly cooling them in water, one can obtain the most intricate ornaments on metal. Such ornaments look especially good if they are covered with colored varnish on top. Try it and you will see that a lot of beautiful things can be made from a simple tin can.