What metal is used for tinning. Purpose and methods of tinning metal. Galvanic tinning of metal in alkaline electrolytes

Soldering allows you to combine elements from different metals and alloys with different physical and mechanical properties into a single product. For example, the method of soldering can be used to connect low-carbon and high-carbon steels, cast iron parts with steel, hard alloy with steel, etc. Particularly noteworthy is the possibility of joining parts made of aluminum and its alloys by soldering. The method of soldering hard alloy plates to holders is widely used in the manufacture of cutting tools.

In a home workshop, soldering is the most accessible form of the formation of fixed, one-piece joints. During soldering, a molten filler metal, called solder, is introduced into the gap between the heated parts. Solder, which has a lower melting point than the metals to be joined, wetting the surface of the parts, connects them when cooled and solidified. In the process of soldering, the base metal and solder, mutually dissolving in each other, provide a high strength of the connection, the same (with high-quality soldering) as the strength of the entire section of the main part.

The process of soldering differs from welding in that the edges of the parts to be joined are not melted, but only heated to the melting temperature of the solder.

To make solder joints, you need: an electric or indirectly heated soldering iron, a blowtorch, solder, flux.

The power of an electric soldering iron depends on the size of the parts to be joined, on the material from which they are made. So, for soldering copper products of small sizes (for example, a wire with a cross section of several square millimeters), a power of 50–100 W is sufficient; when soldering electronic devices, the power of an electric soldering iron should be no more than 40 W, and the supply voltage should not exceed 40 V; large parts require a power of several hundred watts.

The blowtorch is used to heat the indirectly heated soldering iron and to heat the parts to be soldered (for large soldering areas). Instead of a blowtorch, you can use a gas burner - it is more productive and reliable in operation.

The most commonly used solder alloys are tin-lead alloys with a melting point of 180–280 °C. If bismuth, gallium, cadmium are added to such solders, then low-melting solders with a melting point of 70–150 ° C are obtained. These solders are relevant for soldering semiconductor devices. In ceramic-metal soldering, a powder mixture is used as solder, consisting of a refractory base (filler) and low-melting components, which provide wetting of the filler particles and the surfaces to be joined. On sale there are also alloys in the form of bars or wire, which are a symbiosis of solder and flux.

The use of fluxes in the soldering process is based on their ability to prevent the formation of an oxide film on the surfaces of parts when heated. They also reduce the surface tension of the solder. Fluxes must meet the following requirements: maintaining a stable chemical composition and activity in the solder melting temperature range (that is, the flux under the action of these temperatures should not decompose into components), the absence of chemical interaction with the soldered metal and solder, the ease of removal of the products of interaction between the flux and the oxide film ( washing or evaporation), high fluidity. Soldering various metals is characterized by the use of a specific flux: when soldering parts made of brass, silver, copper and iron, zinc chloride is used as a flux; lead and tin require stearic acid; sulfuric acid is suitable for zinc. But there are also so-called universal solders: rosin and soldering acid.

Parts that are supposed to be connected by soldering should be properly prepared: cleaned of dirt, removed with a file or sandpaper the oxide film formed on the metal under the influence of air, pickled with acid (steel - hydrochloric, copper and its alloys - sulfuric, alloys with a large nickel content - nitrogen), degrease with a swab dipped in gasoline, and only after that proceed directly to the soldering process.

You need to heat up the soldering iron. Heating is checked by immersing the tip of the soldering iron in ammonia (solid): if the ammonia hisses and blue smoke comes from it, then the heating of the soldering iron is sufficient; Under no circumstances should the soldering iron be overheated. If necessary, its nose should be cleaned with a file from the scale formed during the heating process, immerse the working part of the soldering iron into the flux, and then into the solder so that droplets of molten solder remain on the tip of the soldering iron, heat the surfaces of the parts with a soldering iron and tin them (that is, cover them with a thin layer molten solder). After the parts have cooled down a bit, tightly connect them together; warm up the soldering place again with a soldering iron and fill the gap between the edges of the parts with molten solder.

If it is necessary to connect large surfaces by soldering, then they act somewhat differently: after heating and tinning the place of soldering, the gap between the surfaces of the parts is filled with pieces of cold solder and at the same time the parts are heated and the solder is melted. In this case, it is recommended to periodically process the tip of the soldering iron and the place of soldering with flux.

The fact that it is unacceptable to overheat the soldering iron has already been said, but why? The fact is that an overheated soldering iron does not hold droplets of molten solder well, but this is not the main thing. At very high temperatures, the solder may oxidize and the joint will be fragile. And when soldering semiconductor devices, overheating of the soldering iron can lead to their electrical breakdown, and the devices will fail (which is why soft solders are used when soldering electronic devices and the effect of a heated soldering iron on the soldering point is limited to 3–5 seconds).

When the soldering site has completely cooled down, it is cleaned of flux residues. If the seam turned out to be convex, then it can be leveled (for example, with a file).

The quality of the soldering is checked: by external inspection - in order to detect unsoldered places, by bending at the place of the soldering - no cracks are allowed (strength test); brazed vessels are checked for tightness by filling with water - there should be no leakage.

There are soldering methods that use hard solder - copper-zinc plates 0.5-0.7 mm thick, or rods with a diameter of 1-1.2 mm, or a mixture of sawdust of copper-zinc solder with borax in a ratio of 1: 2. Soldering iron not used in this case.

The first two methods are based on the use of plate or rod solder. Preparing parts for hard soldering is similar to preparing parts for soft soldering.

Next, pieces of solder are superimposed on the place of soldering and the parts to be soldered together with solder are twisted with a thin knitting steel or nichrome wire (0.5–0.6 mm in diameter). The place of soldering is sprinkled with borax and heated until it melts. If the solder has not melted, then the place of soldering is sprinkled with brown a second time (without removing the first portion) and heated until the solder melts, which fills the gap between the soldered parts.

In the second method, the place of soldering is heated red-hot (without pieces of solder), sprinkled with borax and a solder bar is brought to it (continuing heating): the solder melts and fills the gap between the parts.

Another soldering method is based on the use of a powder mixture as a solder: the prepared parts are heated red-hot at the place of soldering (without solder), sprinkled with a mixture of borax and solder sawdust and continue to heat until the mixture melts.

After soldering by any of the three proposed methods, the soldered parts are cooled and the place of soldering is cleaned from the remnants of borax, solder and binding wire. The soldering quality is checked visually: to detect non-soldered places and strength, the soldered parts are lightly tapped on a massive object - with poor-quality soldering, a kink is formed in the seam.

Varieties of solder joints are shown in fig. 53.

Rice. 53. Designs of soldered joints: a - overlap; b - with two overlaps; in - end-to-end; g - oblique seam; d - end-to-end with two overlaps; e - in Taurus.

In most cases, the parts are first tinned, which makes subsequent soldering easier. The scheme of the tinning process is shown in fig. 54.

Rice. 54. Scheme of tinning with a soldering iron: 1 - soldering iron; 2 - base metal; 3 - zone of fusion of solder with the base metal; 4 - flux; 5 - surface layer of flux; 6 - dissolved oxide; 7 - flux pairs; 8 - solder.

However, tinning can be used not only as one of the stages of soldering, but also as an independent operation, when the entire surface of a metal product is covered with a thin layer of tin to give it decorative and additional performance.

In this case, the covering material is not called solder, but semi-solder. Most often they are tinned with tin, but in order to save money, lead can be added to the half-day (no more than three parts of lead to five parts of tin). The addition of 5% bismuth or nickel to the tin gives the tinned surfaces a beautiful sheen. And the introduction of the same amount of iron into the half-day makes it more durable.

Kitchen utensils (dishes) can only be tinned with pure tin half, the addition of various metals to it is dangerous to health!

The half-day lies well and firmly only on perfectly clean and fat-free surfaces, therefore, before tinning, the product must be thoroughly cleaned mechanically (with a file, scraper, sandpaper to a uniform metallic sheen) or chemically - hold the product in a boiling 10% caustic soda solution for 1–2 minutes, and then etch the surface with a 25% hydrochloric acid solution. At the end of cleaning (regardless of the method), the surfaces are washed with water and dried.

The tinning process itself can be carried out by rubbing, dipping or galvanizing (such tinning requires the use of special equipment, so galvanic tinning at home, as a rule, is not carried out).

The rubbing method is as follows: the prepared surface is covered with a solution of zinc chloride, sprinkled with ammonia powder and heated to the melting point of tin.

Then you should attach a tin rod to the surface of the product, distribute the tin over the surface and grind it with clean tow until a uniform layer is formed. Re-lubricate untinned places. Work should be done in canvas gloves.

In the dip tinning method, tin is melted in a crucible, the prepared part is grasped with tongs or pliers, immersed for 1 minute in a solution of zinc chloride, and then for 3-5 minutes in molten tin. The part is removed from the tin and the excess of the tin is removed by strong shaking. After tinning, the product should be cooled and rinsed with water.

From the book: Korshever N. G. Metalwork

Tinning is the operation of coating the surfaces of metal products with a thin layer of solder, which is tin or a tin-based alloy. A thin layer of tin or a tin-based alloy formed on the surface of the products is commonly called half-baked.

Tinning is widely used in the production of various metal products used in radio engineering, electrical engineering, aviation and other industries. Products that are used for cooking and storing food (pots, buckets, basins, milk cans, cans, pasteurization apparatus, parts of separators, etc.) are subjected to tinning. The tinning operation is a preparatory operation before pouring bearings with babbitt, before soldering products and manufacturing products with seam seams.

The main condition for tinning is to cover the surface of the products with a continuous and impermeable layer of tin or a tin-based alloy. Tin is a good protector of metal from corrosion until: the tin layer covering the surface of the products is damaged.

Tinned products withstand deformation, bending and kinking well without showing damage.

Tinning is carried out mainly by two methods: hot and galvanic.

Hot tinning is performed in two ways: rubbing and immersion. These two methods of hot tinning are the most ancient and widely used so far. The use of hot tinning allows you to do without electric current, special baths and electrolyte solutions.

One of the significant disadvantages of hot tinning is the difficulty, and sometimes even the impossibility, of obtaining a uniform non-porous layer of metal during tinning.

The thickness of the hot tin layer often varies within very large limits. Irregular-shaped products with deep reliefs are covered unevenly, the difference in the thickness of the coating of individual surface areas can be significant. As a result, the amount of tin consumed to cover various kinds of products is very large, in addition, a significant waste of tin is obtained. The disadvantages of hot tinning also include the difficulty of removing impurities that contaminate the molten metal.

Due to the uneven thickness of the layer, the formation of thickenings and sagging in certain areas of the surface, hot tinning of products with narrow holes, with fine cuts, etc. is very difficult, and often completely impossible.

Hot tinning is widely used in the manufacture of products with internal rolled seams (buckets, basins, cans, etc.). At the same time, molten tin, filling holes and sunsets of seams, performs the role of soldering and guarantees complete tightness of products.

Galvanic tinning is carried out in two ways: in acidic electrolytes and in alkaline electrolytes.

Galvanic tinning is widely used, since it provides high adhesion strength of the coating to the base metal or tin-based alloy, allows you to obtain a uniform and any given coating thickness even on products of complex shape, as well as low coating porosity. Alkaline electrolytes, which are used to coat products of complex shape, have a large scattering and hiding power.

Galvanic tinning is more economical than hot tinning in terms of the consumption of tin or tin-based alloys. The disadvantages of galvanic tinning include: the use of baths of a special device and a higher qualification of workers. In addition, the disadvantages of galvanic tinning in alkaline electrolytes include the difficulty of preparing an electrolyte and the instability of the solution composition, which requires constant monitoring and maintenance of the bath and anodes.

Tinning

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Soldering

Tinning

Coating the surface of metal products with a thin layer of an alloy corresponding to the purpose of the products (tin, tin-lead alloy, etc.) is called tinning, and the applied layer is semi-hard.

Tinning, as a rule, is used in preparing parts for soldering, as well as to protect products from corrosion and oxidation.

Tinning is a preparatory operation for filling bearings with babbitt.

Half-baked is prepared in the same way as solder. Tin and tin-based alloys are used as half-days.

Alloys of tin with lead and zinc are used to tin metal products in order to protect them from rust. A beautiful white and shiny semi-tin for artistic items is obtained from tin-bismuth alloys (90-10%).

The pudding process consists of preparing the surface, preparing the polish and applying it to the surface.

Preparing the surface for tinning depends on the requirements for products and on the method of applying the tin. Before coating with tin, the surface is treated with a brush, grinding and degreasing, etching.

Brushes usually treat surfaces; covered with scale or heavily soiled. Before preparation, the products are washed with clean water, and during processing, fine sand, pumice and lime are used to speed up the process.

Irregularities on products are removed by grinding with abrasive wheels and skins.

Chemical degreasing of product surfaces is carried out in an aqueous solution of caustic soda (10 g of soda per 1 liter of water). The solution is poured into a metal bowl and heated to a boil. Then the item is immersed in the heated solution for 10-15 minutes, removed, washed in clean, several times replaced with warm water and dried. On a well-defatted surface, drops of pure water spread.

Fatty substances are removed with Vienna lime. Mineral oils are removed with gasoline, kerosene and other solvents. Copper, brass and steel products are etched for 20-23 minutes in a 20-30% heated sulfuric acid solution.

Tinning is carried out in two ways: by immersion in a semi-dude (small products) and by rubbing (large products).

Tinning by immersion is carried out in a clean metal vessel, where they lay and melt the tin, pouring small pieces of charcoal on the surface to protect it from oxidation. Slowly immersed in the molten half-dude, the products are kept in it until warmed up, then removed, shaking quickly. Excess poluda is removed by wiping with tow sprinkled with powdered ammonia. Then the product is washed in water and dried in sawdust.

Rubbing tinning is performed by first applying zinc chloride to the cleaned area with a hair brush or tow. Then the surface of the product is evenly heated to the melting temperature of the half-day, which is applied from the rod. Sprinkling the tow with powdered ammonia, rub the heated surface with the tow so that the half-day is evenly distributed on it. After that, they heat up and serve other places in the same order. At the end of tinning, the cooled product is wiped with moistened sand, washed with water and dried.

Tinning is the process of coating the surface of a part (product) with a thin layer of molten tin or tin-lead-lead alloys (solder). That part of tin or its alloy, which is applied to the surface of the metal, forms a semi-arc.

Tinning of metal products is carried out in order to protect them from rusting (corrosion), to prepare the surfaces of parts for soldering with soft solders or before pouring bearings with babbitt. Products made, for example, from copper, especially food boilers, oxidize, covered with a green film; food from such dishes is unfit for consumption, as it contains poisonous oxides. Tin, on the other hand, does not undergo oxidation, so it has long been used to protect against corrosion of canning containers, cutlery, kitchen utensils and other products related to the storage, preparation and transportation of food products. Tin is also used to protect contacts and parts of radio equipment from oxidation, to protect cables from the action of sulfur in the electrically insulating layer of rubber, etc. Tin coatings are extremely plastic and easily withstand rolling, stamping and drawing. Parts subjected to tinning are easily soldered.

Choice of half and fluxes. For tinning food boilers and utensils, only pure tin of grades 01 and 02 is used. In particular, tin for cans is tinned with grade 01 tin, containing 99.9% pure tin and no more than 0.1% impurities. Grade 02 with a tin content of 99.5% and impurities of not more than 0.5% is used for tinning kitchen utensils and cooking boilers. For tinning art products, they use a white shiny tin, consisting of an alloy containing 90% tin and 10% bismuth. An alloy consisting of five parts of tin and three parts of lead can be used as a half for non-critical parts. In some cases, tinning is performed with tin-lead solders.

Degreasing and removal of the oxide film from the surface are carried out by etching in an aqueous solution of hydrochloric or sulfuric acid. To protect the cleaned surface of the part from oxidation, it is lubricated with a solution of zinc chloride and sprinkled with ammonia powder on top.

Tinning methods. Half-days can be applied hot and by galvanic or contact deposition. The hot tinning method is carried out in two ways: by immersing the part in a bath with molten semi-metal or rubbing the semi-solid on a surface preheated to 220-250 ° C.

Olo8a can be precipitated from acidic or alkaline electrolytes. The composition of acidic electrolytes includes various elements, for example, tin sulfate 40-50 g / l, sulfuric acid 50-80 g / l, sodium sulfate 50 g / l, technical phenol (crude carbolic acid) or cresol 2-10 g / l, joiner's glue 2-3 g/l, etc. The operating temperature of the bath should be maintained within 15-25 °C.

In the practice of metalworking, it is most often necessary to perform tinning of parts (products) by immersion or grinding. Hot tinning due to its simplicity and ease of implementation is widely used in industry and in some cases replaces the electrolytic tinning method.

The process of hot tinning consists of preparing the surface of the part and semi-work, tinning and final processing of the tinned surface (drying, polishing, etc.).

Preparing the surface for tinning begins with a thorough cleaning of dirt, grease and oxides that prevent an even and durable connection of tin with the metal being tinned. Apply mechanical and chemical cleaning methods.

The mechanical method consists in the fact that the surface of the part is cleaned to a shine using scrapers, files, abrasive skins, mechanized brushes, etc.

The chemical method of preparation is reduced to etching the metal surface with acids. The surfaces of parts made of steel, copper, brass are most often treated with a 20-30% aqueous solution of sulfuric acid for 15-25 minutes. Copper and brass parts can be etched with a solution containing 10% sulfuric acid, 5% potassium chromium peak and 85% water. Etching is carried out in baths - glass, metal, enameled, etc. Exposure during etching of the surfaces of parts in such a solution is 1.5-2 minutes. Preparation for tinning ends with a thorough rinsing of the part in running water, cleaning the surface with wet sand, a final rinsing in hot water, rubbing and drying. To protect the cleaned surface from oxidation, it is lubricated with a solution of zinc chloride and sprinkled with ammonia powder on top.

Tinning techniques. Tinning by the method of immersion in a molten tin consists in the fact that the part prepared for tinning is first immersed in a bath with a solution of zinc chloride, then with the help of tongs, pliers or special hooks, the part is removed from the bath and, without removing zinc chloride from the surface, is immersed in a bath with molten half-day, keeping it in it for 2-3 minutes. After that, the tinned part is removed from the bath and immediately shaken to remove excess tin. While the part is still hot, it is quickly wiped with tow and ammonia to obtain a uniform, pore-free and smooth layer of semi-deep. After cooling, the part is washed in water and dried. Drying in sawdust gives good results.

Let us trace the process of tinning by the method of immersion using a specific example. Let's say that you need to irradiate the outer and inner surfaces of three metal tanks with a capacity of 2 liters each. The work should be performed sequentially in four transitions (stages).

The first transition is to clean the tanks and prepare a 10% solution of caustic soda for degreasing. Heat the solution to 70-80 °C. Then, one by one or together, immerse the tanks in a degreasing bath and soak in it for 15-20 minutes, depending on the degree of contamination of the tanks, then rinse them thoroughly and dry over a heat source.

The second step is to chop the tin into small pieces, immerse them in a bath and heat until melted.

The third transition is to make a 5-7% hydrochloric acid solution and heat it to 35-40 ° C, then immerse the tanks in the bath and soak in it for 30-40 minutes. After the etching, the tanks are thoroughly rinsed in running water and dried.

The fourth transition is to prepare a flux (25% zinc chloride solution) and immerse the tanks in it. Then, one by one, remove them from the zinc chloride bath and slowly immerse them in a bath of molten tin. After 2-3 min. remove the tanks from the bath, shake quickly and wipe with a tow sprinkled with ammonia powder to remove excess tin and get an even and smooth, pore-free layer of tin. After that, rinse the tanks in running water and dry in sawdust.

When tinning by rubbing, the surface of the part prepared for tinning is lubricated with a solution of zinc chloride, then sprinkled with ammonia and heated evenly with a blowtorch flame or in a charcoal furnace. When zinc chloride begins to boil, tin is applied to the surface of the part in the form of small pieces or powder. The half, having come into contact with the heated surface of the part, will begin to melt; it is immediately rubbed with a canvas rag or tow sprinkled with ammonia powder. You need to rub the floor quickly, gradually moving from one area of ​​​​the surface to be coated to another.

In the process of tinning, it is necessary to carefully monitor the heating of the part, since the half-shell burns out when overheated. A sign of overheating is the appearance of a bluish tint on the surface of the half. The tinned surfaces should be wiped with wet sand, thoroughly rinsed with clean water, dried and, if necessary, polished with a soft cloth or flannel. If places with defects in tinning are found (non-adhering semilude, porosity, etc.), they must be cleaned again, pickled and re-tinned by immersion or grinding. It should be remembered that the better the surface is prepared for the coating, the smoother the floor will lie and the stronger the layer will be.

When describing the technological processes of soldering, tinning was mentioned - coating metal parts with a thin layer of solder.

However, tinning can be used not only as one of the stages of soldering, but also as an independent operation, when the entire surface of a metal product is covered with a thin layer of tin to give it decorative and additional performance. In this case, the covering material is not called solder, but semi-solder. Most often they are tinned with tin, but in order to save money, lead can be added to the half-day (no more than three parts of lead to five parts of tin). Adding 5% bismuth or nickel to the tin gives a beautiful sheen to tinned surfaces. And the introduction of the same amount of iron into the half-day makes it more durable.

Kitchen utensils (dishes) can only be tinned with pure tin half, the addition of various metals to it is dangerous to health!

The half-day lies well and firmly only on perfectly clean and fat-free surfaces, therefore, before tinning, the product must be thoroughly cleaned mechanically - with a file, scraper, sandpaper to a uniform metallic sheen, or chemically - hold the product in a boiling 10% solution of caustic soda for 1-2 minutes, then etch the surface with a 25% hydrochloric acid solution. At the end of cleaning (regardless of the method), the surfaces are washed with water and dried.

The tinning process itself can be carried out by rubbing, dipping or galvanizing (such tinning requires the use of special equipment, so galvanic tinning at home is usually not carried out).

The rubbing method consists in the following, the prepared surface is covered with a solution of zinc chloride, sprinkled with ammonia powder and heated to the melting point of tin.

TINNING , a method of mechanically applying pure or lead-containing tin to the surface of metal products (iron, copper, brass) in order to give them a more beautiful appearance or to protect them from corrosion to one. The L. process proceeds differently depending on the nature and grade of the product being processed. The main stages of work with L. consist of the following points. Items intended for half-day are first thoroughly cleaned and degreased with salt or sulfuric acid and then a layer of rust is removed from their surface by scraping; after that, the products are dipped into melted fat and then immersed in molten tin or in a mixture of tin and lead. To remove excess tin and zinc chloride, which is also often used for pre-treatment of products, objects removed from the molten metal are manually cleaned with brushes. tretnik-an alloy containing about 2/3 of lead. With this method, the object is preheated either with a blowtorch or more often on fire over braziers or forges, and then the tinker, holding a bar of tretnik in his hand, draws it over the surface of the product. In this way, various kinds of tanks and pots are usually tinned (for water, gasoline, acids, etc.). - Iron sheets are tinned in a special way; they are passed through special machines equipped with troughs and rollers, where they sequentially pass through different layers - molten tin, zinc chloride, oil; after the end of the half-day, the sheets are polished with bran or flour. Application at L. to - t causes formation of acid vapors in the course of work with them, to-rye, getting into room air, exert the harmful influence on workers which is expressed in strong irritation of a mucous membrane of eyes and respiratory tracts, and also in defeat of lungs ( inflammation) and tooth decay. More serious consequences with pronounced phenomena prof. poisoning can occur in case of application to - t. containing arsenic (sulfuric acid obtained by chamber method). Here, from the action of to-t on metals, the formation of arsenic hydrogen and the appearance of symptoms in workers characteristic of poisoning with this poisonous gas are possible. Preliminary cleaning of products from rust, with a cut, sand is often used, as well as the removal of excess metal from the surface of the object after L. contribute to the formation of silicate and metal dust, especially ferrous oxide. Separate cases are described (Label 1) of deposits in the lungs of these substances as a result of the production of these works. The most serious and important prof. the harmfulness inherent in the profession of tinkers is the use of lead in L. With the exception of utensils intended for cooking and storing food and drinking water, when tinning, the use of lead is limited by law [according to the Soviet (Bull. NKZdr, No. 24, 1927) and German laws, its content in tin should not exceed 1%], in the afternoon of all other products, the use of lead became very widespread. The lead content in the metal mixture used for L. ranges from 14% (babit) to 65% (tretnik), and during lead plating, which is a variation of the L. process, objects are immersed in pure lead. Tinning refers to hot work, during which, due to the use of lead, lead fumes can form, which, when cooled, turn into very fine dust particles (less than 0.5 /G), having the ability to penetrate into the deepest parts of the lungs, where they are absorbed and very soon enter the bloodstream. This is the direct cause of the appearance of lead poisoning in workers. Recently, Froboese has established that during processes similar to L. (soldering, lead plating, etc.), lead is released into the air not only in the form of dust or vapor visible to the eye, but also in the form of a special colloid state, which is lead oxide. The content of lead in the air of the working room in the form of a colloid should pose a particularly serious danger to persons inhaling this air, since under these conditions all the lead distributed in it, being in a state of very high dispersion, will be completely absorbed by the respiratory organs. This, apparently, is the reason for the relatively frequent cases of lead poisoning observed among tinkers, despite the fact that the concentration of lead dust during these works turned out to be insignificant - 0.07-0.09 burning per 1 m 3.- In addition to lead inhalation, tinkers have to work directly b. or m. constantly come into contact with lead, due to which they have a rather significant contamination of their hands with lead, which fluctuates depending on different working conditions and gives in some cases over 20 mg lead in hand washings. Such contamination of the hands of tinkers can pose some danger in the sense that lead, mixing with fat, which is richly lubricated hands of an tinker who uses oil during work, can form a readily soluble compound with fatty acids, which has the ability to be quickly absorbed through skin (Flury), which may increase the risk of lead poisoning in tinkers. Measures to combat the hazards of work with L. should basically be as follows. It is necessary, wherever possible, to completely exclude lead from the metal mixture used for L., or at least reduce its content to a minimum. Only to-you, completely free from arsenic, should be allowed for use in these works. For dust suction during processes accompanied by its formation and release into the air, it is necessary to arrange local dust-removing ventilation devices. Warming up of products, processing them to - that and process L. have to be allowed only in the rooms which are specially adapted for these works and equipped with appropriate ventilating installations. In addition, the workers must also observe those general rules of personal hygiene, which are recommended for other work associated with the danger of lead poisoning (see. Lead).Lit.--cm. lit. to Art. Lead. D. Kagan.

You probably noticed that when two conductors connected to each other, they start to warm up during long work. This is especially noticeable when the power of the passing current increases. This phenomenon occurs when an oxide film forms between the conductors, which breaks the contact. Insufficient contact between the wires leads to their heating. To ensure a long and reliable contact, the process of tinning the wires is used.

How to tin a soldering iron: features

Tinning means covering metal products with a thin layer of tin, which in turn prevents the process of oxidation of metal surfaces. But if we take into account the maintenance of the soldering iron, then the process is slightly different.

Tinning the soldering iron step by step:

• Surface preparation;
• Tinning.

Before irradiating the soldering iron, it is necessary to prepare the work surface. First of all, if the soldering iron is brand new, you need to sharpen the tip of the device. In order to do this correctly, you should consider the processes in which the soldering iron will be used.

The tip of the soldering iron can be shaped like a wedge. To do this, the sting is removed from the device, and with the help of a file or a power machine, the sting is sharpened on both sides at an angle of up to 40 0 ​​. If the soldering iron is used to work with small radio components, then it is given a cone shape, which provides more convenient work.

Note! The width of the wedge tip must be at least one millimeter. If the sting is in the form of a cone, then the working area is about two millimeters.

If the factory shape of the sting suits, then it is important to understand that all products at the factory are covered with patina - oxygen and copper oxide, which has a greenish tint. Before tinning the tip of the device, it is necessary to remove this coating using fine-grained sandpaper.

After that, the sting is installed in the device and connected to the mains. It is necessary to wait for a uniform heating of the tip surface, after which tinning is carried out.

When heated to the optimum temperature, the sting of the device is treated with resin or a piece of rosin. The entire surface is covered.

Wire tinning: technology

Copper and its alloys oxidize over time when exposed to oxygen. In order for the connections of copper conductors not to oxidize during operation, it is necessary to tin them with tin.

For work you will need:

• soldering iron;
• Solder;
• Flux or rosin.

Correctly tin the copper wire, it will turn out only with a well-heated soldering iron. Therefore, before starting work, we turn it on and leave it to warm up.

After that, depending on the processing material, the following is performed. If the copper core is covered with rosin, then it is placed in a container with this material and heated with a soldering iron. If flux is used, then the wire is covered with liquid flux and heated with a soldering iron.

Note! The better the heating of the metal, the better the tinning of the copper conductor.

Then, the required amount of tin is taken onto the heated tip of the soldering iron and, using this device, it is distributed over the entire surface of the processed wire.

In order to tin a copper cable of large cross section, a crucible (melting vessel) is used. In this case, pieces of metal are placed in a heated container to the melting point of tin. The cable core is treated with flux or rosin and placed in a crucible. Thus, normal heating of the core and uniform distribution of tin over its surface are achieved.

What you need and how to tin and solder the wires from the headphones

Very often, under the influence of mechanical loads, headphones fail. This leads to a break in low-current conductors. These conductors in the device are quite thin, so the technology of tinning and soldering is slightly different.

Work features:

• Thin soldering iron tip;
• The use of rosin;
• Application of solder wire.

To start work, you should disassemble the old device. First of all, broken conductors are soldered. Next, preparations are made for soldering a new wire.

Since low-current conductors for headphones are varnished for isolation from each other, this somewhat complicates the soldering process. To do this, to facilitate the work, it is necessary to remove the layer of varnish from the wires, thereby preparing the metal for tinning.

This is done using a heated soldering iron using rosin. The core of the wire is placed in rosin and heated. Then it is placed on a flat surface, on which a layer of varnish is peeled off with light movements from the insulation to the end of the wire.

Note! The varnish should be removed to such a distance that touching the conductors will not lead to their short circuit.

After that, using a heated soldering iron, the wires are covered with a thin layer of tin. It is worth noting that the tinned headphone wires not only provide reliable contact, but the soldering process is greatly simplified.

Tinned Copper: Characteristics and Applications

Due to its properties, copper wire has found wide application, both in domestic and industrial scales. The main feature of copper is resistance to various mechanical influences, temperature changes and the influence of precipitation.

But to improve the stability of copper, a tinning process is used, in which it is covered with a thin layer of tin, the thickness of which varies from 1 to 20 microns.

Copper wire tinning process:

• cleaning;
• Tinning;
• Leveling the tin layer;
• Cooling;
• Re-alignment;
• Package.

First of all, the coil with wire is installed on a special feeder, through which it goes through all the necessary processes.

First, passing through special brushes that are wetted with a solution of zinc chloride, the wire is cleaned. A solution of zinc chloride is obtained by dissolving granular zinc in hydrochloric acid.

After the wire has been cleaned, it passes through a bath filled with molten tin. This method makes it possible to achieve a uniform distribution of tin over the entire surface of the metal.

Note! The most important thing when tinning copper wire is to prevent tin build-up.

Then, the wire is cooled. This happens when it passes through a bath filled with cold water. This process performs the function of improving the quality of the connection of tin with the copper surface of the wire.

After that, the wire undergoes secondary processing with brushes, in which the wire completely gets rid of sagging and, if necessary, its diameter is reduced.

On the take-up mechanism, the wire is wound on a spool and packed.

How to irradiate a bearing with tin (video)

It does not matter what design the metal product has (wire or bearing). Quite often, the correct operation of these products depends on the quality of the connection and the materials with which it is processed.