K.: Technika, 1989. - 191 p.
ISBN 5-335-00257-3
Download(direct link) : sputnik_galvanika.djvu Previous 1 .. 8 > .. >> Next

In electrochemical milling, a coating of any acid-resistant paint applied by a stencil can serve as a protective coating. The pickling solution in this case consists of 150 g/l sodium chloride and 150 g/l nitric acid. Etching occurs at the anode at a current density of 100–150 A/dm2. Copper plates are used as the cathode. After the termination of the process, the cathodes are removed from the bath.

Electrochemical milling is more accurate than chemical milling.

PRE-TREATMENT OF ALUMINUM AND ITS ALLOYS

To ensure strong adhesion of the electrolytic coating to aluminum, an intermediate layer of zinc, iron or nickel is applied to the surface of the latter (Table 21).

CHEMICAL AND ELECTROCHEMICAL POLISHING

A smooth metal surface can be obtained by chemical or electrochemical (anodic) polishing (Tables 22, 23). The use of these processes makes it possible to replace mechanical polishing.

When aluminum is oxidized, mechanical polishing is not enough to achieve a shiny surface; after it, chemical polishing is necessary.

21. Solutions for aluminum pretreatment

Orthophosphoric acid Glacial acetic Orthophosphoric acid

280-290 15-30 1-6

Acid Orange * For:

dye 2

pinned surface

1st intermediate processing

ratu-ra. FROM

4. orthophosphorus!

Triethane! lamin

500-IfXX) 250-550 30-80

Triethanolamine Catalin BPV

850-900 100-150

Orthophs ph rthic acids Chromic thydrnd

* Products ps mining are processed by flushing in the same mine 6A / dm2

trochemical polishing When precious metals are polished by chemical or electrochemical methods, their losses are completely eliminated. Electrochemical and chemical polishing can be not only a preparatory operation before electroplating, but also the final stage of the technological process. It is most widely used for aluminum. Electrochemical polishing is more economical than<ими-ческое.

The current density and duration of the electropolishing process are selected depending on the shape, size and material of the products.

COATING PROCESS TECHNOLOGY

SELECTION OF ELECTROLYTES AND PROCESSING MODES

The quality of the metal coating is characterized by the structure of the precipitate, its thickness and uniformity of distribution on the surface of the product. The structure of the precipitate is influenced by the composition and pH of the solution, the hydrogen released together with the metal, the electrolysis mode - dark

polishing

M41
with SS
Density
„|§..
cathodes

From sent
carbonaceous

I-IL
15-18
1,63-1,72
12XI8H9T, over

1-5
10-100

From steel 12X18H97
H:rusty1d

From styles 12X18H9T Aluminum and 3-5 20-50 - (aluminum) stainless

0.5-5.0 20-50 1.60-1.61 From copper or evine Copper

temperature, density of the goka, the presence of swing, filtration and 1. d.

To improve the structure of the precipitate, various organic additives (glue, gelatin, saccharin, etc.) are introduced into electrolytes, complex salts are precipitated from solutions, the temperature is increased, continuous filtration is used, etc. The released hydrogen can be absorbed by the precipitate, contributing to an increase in brittleness and porosity. , and the appearance of so-called pitting points. To reduce the effect of hydrogen on the quality of the precipitate, the parts are shaken during the process, oxidizing agents are introduced, the temperature is increased, etc. The porosity of the precipitate decreases with increasing thickness.

The uniform distribution of the precipitate on the surface and delirium depends on the scattering ability of the electrolyte. Alkaline and cyanide electrolytes have the best scattering ability, acidic electrolytes are much less, and chromium electrolytes are the worst.

When choosing an electrolyte, it is necessary to take into account the configuration of the products and the requirements that apply to them. For example, when coating products of a simple shape, you can work with simple in composition electr>-

lantamn that do not require heating, ventilation, filtration; when coating products of complex shape, solutions of complex metal salts should be used; for coating internal and hard-to-reach surfaces - internal and additional anodes, filtration, mixing; to obtain a brilliant coating - electrolytes with complex brightening and leveling additives, etc.

GENERAL SCHEME OF THE TECHNOLOGICAL PROCESS

The coating process consists of a series of sequential operations - preparatory, coating and final processing. Preparatory operations include machining [parts, degreasing in organic solvents, chemical or electrochemical degreasing, etching and polishing. The final processing of coatings includes dehydration, clarification, passivation, impregnation, polishing, brushing. After each operation

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 (another's 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 realize 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.

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 picture is carried out by the following methods: manual and mechanized engraving on the overcast (lacquer, wax) layer, xerography, screen, offset, 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, bichromate, 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).

Chemical methods of processing materials are called, in which the removal of a layer of material occurs due to chemical reactions in the processing zone. Advantages of chemical processing methods: a) high productivity, provided by relatively high reaction rates, primarily the lack of dependence of productivity on the size of the treated surface area and its shape; b) the possibility of processing especially hard or viscous materials; c) extremely low mechanical and thermal effects during processing, which makes it possible to process parts of low rigidity with a sufficiently high accuracy and surface quality.

Dimensional deep etching (chemical milling) is the most common chemical processing method. It is advisable to use this method for processing surfaces of complex shapes on thin-walled parts, obtaining tubular parts or sheets with a smooth change in thickness along the length, as well as when processing a significant number of small parts or round blanks with large; the number of processed places (perforation of cylindrical surfaces of pipes). By local removal by this method from excess material in unloaded or lightly loaded aircraft and missiles, the overall weight can be reduced without reducing their strength and rigidity. In the United States, the use of chemical milling has reduced the weight of a supersonic bomber wing by 270 kg. This method allows you to create new structural elements, such as sheets 1 of variable thickness. Chemical milling is also used in the manufacture of printed circuits for electronic equipment. In this case, the sections specified by the scheme are removed from the panel of insulating material, covered on one or both sides with copper foil, by etching.

The technological process of chemical milling consists of the following operations.

1. Preparation of parts for chemical milling to ensure subsequent tight and reliable adhesion of the protective coating to the surface of the part. For aluminum alloys, this preparation is carried out by: degreasing in B70 gasoline; light pickling in a bath with caustic soda 45-55 g/l and sodium fluoride 45-55 g/l at a temperature of 60-70 ° C for 10-15 minutes to remove the clad layer; washing in warm and cold water and clarification in nitric acid, followed by washing and drying. For stainless and titanium alloys, parts are prepared by pickling to remove scale in a bath with hydrofluoric (50-60 g/l) and nitric (150-160 g/l) acids or in a bath with electric heating up to 450-460 ° C in caustic soda and sodium nitrate (20%) followed by washing and drying, degreasing and light pickling followed by repeated washing and drying.

2. Application of protective coatings to the places of the workpiece that are not subject to etching. It is produced by installing special overlays, chemically resistant adhesive-type templates or, most often, by applying paint coatings, which are usually used as perchlorovinyl varnishes and enamels, polyamide varnishes and materials based on non-prene rubbers. So, for aluminum alloys, PKhV510V enamel, RS1 solvent TU MHP184852 and KhV16 enamel TU MHPK-51257, R5 TU MHP219150 solvent are recommended, for titanium alloys - AK20 glue, RVD thinner. For better adhesion of these coatings to metal, anodizing of the surface is sometimes preliminarily performed. The application of paint and varnish coatings is carried out with brushes or spray guns with preliminary protection of the places of etching with templates or by immersion in a bath; in the latter case, the contour is marked on the dried protective film, then it is cut and removed.

3. Chemical dissolution is carried out in baths in compliance with the temperature regime. Chemical milling of aluminum and magnesium alloys is carried out in solutions of caustic alkalis; steels, titanium, special heat-resistant and stainless alloys - in solutions of strong mineral acids.

4. Cleaning after etching of parts made of aluminum alloys with an enamel protective coating is carried out by washing in running water at a temperature of 50 + 70 ° C, soaking the protective coating in hotter running water at a temperature of

70-90 ° С and subsequent removal of the protective coating with knives manually or with soft brushes in a solution of ethyl acetate with gasoline (2: 1). Then produce clarification or light etching and drying.

The quality of the surface after chemical milling is determined by the initial surface roughness of the workpiece and the etching modes; usually it is 1-2 classes lower than the cleanliness of the original surface. After etching, all defects previously present on the workpiece. (risks, scratches, irregularities) retain their depth, but broaden, acquiring greater smoothness; the greater the depth of etching, the more pronounced these changes. The quality of the surface is also affected by the method of obtaining blanks and their heat treatment; rolled material gives a better surface than stamped or pressed material. Large surface roughness with pronounced irregularities is obtained on cast billets.

The surface roughness is affected by the structure of the material, grain size and orientation. Hardened aluminum sheets subjected to aging have a higher surface finish class. If the structure is coarse-grained (for example, the metal is annealed), then the finished surface will be with large roughness, uneven, bumpy. The fine-grained structure should be considered the most suitable for chemical processing. Carbon steel blanks are best treated by chemical milling before hardening, since in the case of hydrogenation during pickling, subsequent heating helps to remove hydrogen. However, it is desirable to harden thin-walled steel parts before chemical treatment, since subsequent heat treatment can cause them to deform. The surface treated by chemical milling is always somewhat loosened due to pickling, and therefore this method significantly reduces the fatigue characteristics of the part. Given this, for parts operating under cyclic loads, it is necessary to carry out polishing after chemical milling.

Chemical milling accuracy ±0.05 mm po. depth and not less than +0.08 mm along the contour; the radius of curvature of the cutout wall is equal to the depth. Chemical milling is usually performed to a depth of 4-6 mm and less often up to 12 mm; with a larger milling depth, the surface quality and machining accuracy deteriorate sharply. The minimum final thickness of the sheet after etching can be 0.05 mm, therefore, chemical milling can process parts with very thin bridges without warping, and perform conical processing by gradually immersing the part in the solution. If it is necessary to pickle from two sides, you must either position the workpiece vertically so as to allow the released gas to freely rise from the surface, or pickle in two steps - 1 first on one side and then on the other. The second method is preferable, since with a vertical arrangement of the workpiece, the upper edges of the cutouts are processed worse due to gas bubbles entering there. In the manufacture of deep cuts, special measures (for example, vibrations) should be used to remove gas from the machined surface, which prevents the normal process from being carried out. Depth control, etching during processing is carried out by immersion Simultaneously with the preparation of control samples, direct control of dimensions by thickness gauges such as an indicator bracket or electronic ones, as well as by automatic weight control.

The productivity of chemical milling is determined by the rate of material removal in depth. The rate of etching increases with an increase in the temperature of the solution by about 50-60% for every 10 ° C, and also depends on the type of solution, its concentration and purity. Mixing of the solution during the pickling process can be done with compressed air. The etching process is determined by an exothermic reaction, so the supply of compressed air cools it somewhat, but basically the constancy of temperature is ensured by placing water coils in the bath.

Etching by immersion has a number of disadvantages - the use of manual labor, partial breakdown of protective films on untreated surfaces. When processing a number of parts, the jet etching method is more promising, in which alkali is supplied by nozzles.

A means of increasing the productivity of chemical milling is the use of ultrasonic vibrations with a frequency of 15-40 kHz; in this case, the processing productivity increases by 1.5-2.5 times - up to 10 mm/h. The process of chemical treatment is also greatly accelerated by the influence of infrared radiation of directional action. Under these conditions, there is no need to apply protective coatings, since the metal is subjected to strong heating along a given heating circuit, the remaining areas, being cold, practically do not dissolve.

The etching time is set empirically on control samples. The pickled workpieces are removed from the pickling machine, washed in cold water, and to remove the emulsion, paint and BF4 glue, they are treated at a temperature of 60-80 ° C in a solution containing 200 g/l of caustic soda. The finished parts are thoroughly washed and dried in a stream of air.

Improving the conditions for roughing workpieces by cutting by first removing the skin by etching is another example of the dissolving action of a reagent. Before pickling, the workpieces are blown with sand to remove scale. Etching of titanium alloys is carried out in a reagent consisting of 16% nitric and 5% hydrofluoric acids and 79% water. According to foreign literature, for this purpose, etching in salt baths is used, followed by washing in water and then repeated etching in acid etchants for final cleaning of the surface.

The chemical impact of the technological environment is also used to improve conventional cutting processes; methods of processing materials based on a combination of chemical and mechanical effects are increasingly being used. Examples of already mastered methods are the chemical-mechanical method of grinding hard alloys, chemical polishing, etc.

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. At the same time, 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 deepening 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 contour of the deepening 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 a 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 billet 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 insulated 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. By 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 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 so 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 waste removal 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 use the second “bowl” to start 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 tin can 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 table salt and then slowly driven over the surface of the tin, then amazing things will happen to it. In those places where you brushed it 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 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 is melted locally and quickly cooling them in water, it is possible to 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.