The choice of solder depends on the metals or alloys being joined, on the soldering method, temperature limits, dimensions of parts, required mechanical strength, corrosion resistance, etc. Low-melting solders are most widely used in amateur practice. Recommendations for their use, on the basis of which you can choose solder, are given in the table. The letters POS in the solder brand mean tin-lead solder, the numbers indicate the tin content in percent (POS 61, POS 40). To obtain special properties, antimony, cadmium, bismuth and other metals are introduced into the composition of tin-lead solders. The composition of some of these solders is given in the table. Low-melting solders are produced in the form of cast ingots, rods, wire, foil strips, powders, tubes with a diameter of 1 to 5 mm, filled with rosin, as well as in the form of pastes composed of solder powder and liquid flux.
Low-melting solders.
| Brand | Melting temperature, °C | Application area |
| POS90 | 222 | Soldering of parts and assemblies subjected to further galvanic processing (silvering, gilding) |
| POS61 | 190 | Tinning and soldering of thin spiral springs in measuring instruments and other critical parts made of steel, copper, brass, bronze, when high heating in the soldering zone is unacceptable or undesirable. Soldering of thin (0.05-0.08 mm in diameter) winding wires, including high-frequency (Litz wire), winding leads, radio elements and microcircuits, installation wires in PVC insulation, as well as soldering in cases where increased mechanical strength and electrical conductivity |
| POS50 | 222 | The same, but when higher heating is allowed than with POS 61 |
| POS40 | 235 | Tinning and soldering of conductive parts for non-critical purposes, tips, connections of wires with petals, when higher heating is allowed than with POS 50 or POS 61 |
| POSZO | 256 | Tinning and soldering of non-critical mechanical parts made of copper and its alloys, steel and iron |
| POS 18 | 277 | Tinning and soldering with reduced requirements for weld strength, non-critical parts made of copper and its alloys, galvanized iron, steel |
| POSSU 4-6 | 265 | Tinning and soldering of copper and iron parts by immersion in a bath of molten solder |
| POSK 50 | 145 | Soldering of parts made of copper and its alloys that prevent local overheating. Soldering of semiconductor devices |
|
POSV 33 POSK 47-17 |
130 180 |
Soldering fuses Soldering wires and element leads to a layer of silver deposited on ceramics using the burning method |
|
P200 P250 |
200 280 |
Soldering of thin-walled parts made of aluminum and its alloys |
|
Alloy Rose Alloy d'Arsenral Wood's alloy |
92-95 79 60 |
Soldering when a particularly low melting point of solder is required |
Composition of some special low-melting solders.
| Brand | Element content, % | Melting temperature, °C | |||||
| Sn | Pb | Sb | Bi | Cd | Zn | ||
| POSSU 4-6 | 3-4 | 90-92 | 5-6 | - | - | 265 | |
| POSK 50-18 | 49-51 | 29,8-33,8 | 0,2 | - | 17-19 | - | 222 |
| POSV 33 | 33,4 | 33,3 | - | 33,3 | - | - | 130 |
| P250 | 80 | - | - | - | - | 20 | 280 |
| P200 | 90 | - | - | - | - | 10 | 200 |
| Alloys Rose | 15,5 | 32 | - | 52,5 | - | - | 95 |
| 25 | 25 | - | 50 | - | - | 94 | |
| - | 40 | - | 52 | 8 | - | 92 | |
| Alloy d'Arsenval | 9,4 | 45,1 | - | 45,5 | - | - | 79 |
| Wood's alloy | 12,5 | 25 | - | 50 | 12,5 | - | 60 |
Fluxes
Fluxes dissolve and remove oxides and contaminants from the surface of the soldered joint. In addition, during soldering they protect the surface of the heated metal and the molten solder from oxidation. All this helps to increase the spreadability of solder, and therefore improve the quality of soldering. The flux is selected depending on the properties of the metals or alloys being joined by soldering and the solder used, as well as on the soldering method. Remains of flux, especially active flux, and its decomposition products must be removed immediately after soldering, as they contaminate joints and are sources of corrosion. When installing electrical and radio equipment, the most widely used are rosin and fluxes prepared on its basis with the addition of inactive substances - alcohol, glycerin and even turpentine. Rosin is not hygroscopic and is a good dielectric, so its remaining residue does not pose a danger to the solder joint. Data on the fluxes most often used in amateur practice are given in the tables.
Inactive (acid-free) fluxes
Active (acid) fluxes
| Compound, % | Application area | Residue removal method |
| Zinc chloride - 25-30; concentrated hydrochloric acid - 0.6-0.7; water - the rest | Soldering of parts made of ferrous and non-ferrous metals | Thorough rinsing with water |
| Zinc chloride (saturated solution) - 3.7; technical petroleum jelly - 85; distilled water - the rest (flux paste) | The same thing when, due to the type of work, it is more convenient to use paste | Same |
| Zinc chloride - 1.4; glycerin - 3; ethyl alcohol - 40; distilled water - the rest | Soldering of nickel, platinum and its alloys | Same |
| Rosin - 24; zinc chloride - 1; ethyl alcohol - the rest | Soldering of non-ferrous and precious metals (including gold), critical parts made of ferrous metals | Washing with acetone |
| Rosin - 16; zinc chloride - 4; technical petroleum jelly - 80 (flux paste) | The same, for obtaining connections of increased strength, but only parts of a simple configuration that does not complicate washing | Same |
Soldering aluminum with POS solders
Difficult, but still possible if the tin-lead solder contains at least 50% tin (POS 50, POS 61, POS 90). Mineral oil is used as a flux. The best results are obtained when using alkaline oil (for cleaning the weapon after shooting). Satisfactory soldering quality is ensured by mineral oil for sewing machines and precision mechanisms. Flux is applied to the soldering site and the surface of the aluminum under the oil layer is cleaned with a scraper or a knife blade to remove the oxide film that is always present on the surface of the aluminum. Solder with a well-heated soldering iron. For soldering thin aluminum, a soldering iron power of 50 W is sufficient; for aluminum 1 mm thick or more, a power of 90 W is desirable. When soldering aluminum with a thickness of more than 2 mm, the soldering area must be preheated with a soldering iron and only then apply flux.
Soldering aluminum with P200 and P250 solders
The corrosion resistance of solder joints made with these solders is somewhat lower than those made with tin-lead solders. The flux is a mixture of oleic acid and lithium iodide. Lithium iodide (2-3 g) is placed in a test tube or flask and 20 ml (about 20 g) of oleic acid is added (the flux can contain from 5 to 17% lithium iodide.) The mixture is slightly heated by immersing the test tube in hot water and stirred until the salt is completely dissolved. The finished flux is poured into a clean glass container and cooled. If an aqueous lithium salt is used, then when it is dissolved, a layer of the aqueous mixture drops to the bottom of the test tube, and the flux floats to the surface and is carefully poured off. Before soldering, the tip of a well-heated soldering iron (tip temperature should be about 270-350 °C) is cleaned and tinned with solder, using clean rosin. The surfaces of the parts to be joined are moistened with flux, tinned and soldered. After cooling, the remaining flux is removed with a cloth swab soaked in alcohol, acetone or gasoline, and the seam is covered with a protective varnish. During the soldering process, flux does not emit toxic or pungent odor substances. It is easily washed off from fabric and skin with soap and water.
Soldering nichrome (nichrome with nichrome, nichrome with copper and its alloys, nichrome with steel)
It can be done by soldering POS 61, POS 50 (worse -, POS 40) using flux of the following composition (in grams): petroleum jelly - 100, zinc chloride powder -. 7, glycerin - 5. The flux is prepared in a porcelain mortar, into which Vaseline is placed, and then zinc chloride and glycerin are added, mixing well until a homogeneous mass is obtained. The surfaces to be joined are thoroughly cleaned with sandpaper and wiped with a cotton swab soaked in a 10% alcohol solution of copper chloride, flux is applied, tinned and only then soldered.
Brazing of galvanized steels
Soldering of steels galvanized with zinc or cadmium is possible with tin-lead solders using a soldering iron using zinc chloride as a flux (clause 10.13). Soldering with rosin fluxes does not provide a high-quality connection.
Solder paste
When soldering at home, solder is usually picked up and applied with a soldering iron. It is extremely difficult to control the amount of molten solder transferred by a soldering iron: it depends on the melting temperature of the solder, the temperature and cleanliness of the tip, and other factors. It is possible that drops of molten solder will get on conductors, element housings, and insulation, which sometimes leads to undesirable consequences. You have to work extremely carefully and accurately, and yet it can be difficult to achieve good soldering quality. You can make soldering easier and improve it using solder paste. To prepare the paste, grind the solder with a file with a large notch (fine ones are clogged with solder) and mix the sawdust with alcohol-rosin flux. The amount of solder in the paste is selected experimentally. If the paste turns out to be too thick, alcohol is added to it. The paste should be stored in a tightly sealed container. The paste is applied to the soldering site in the required doses with a metal spatula. The use of solder paste, in addition, avoids overheating of small parts and semiconductor devices.
"Soldering tape"
Indispensable when splicing conductors, tubes, rods, when it is not possible to use an electric soldering iron. To make "soldering tape", you must first prepare a paste of solder filings, rosin and petroleum jelly. The paste is applied in a thin, even layer onto the calico tape. The soldering area is wrapped in one layer of “soldering tape”, moistened with gasoline or kerosene and set on fire. It is advisable to tin the pre-connected surfaces.
Tinning of wires in enamel insulation
When stripping the output ends of the winding wire LESHO, PELSHO, PEL and PEV using sandpaper or a blade, cuts and breaks of thin wire strands are common. Stripping by firing also does not always give satisfactory results due to the possible melting of small-section wires. In addition, at the place of firing, the wire loses strength and breaks easily. To strip small cross-section wires in enamel insulation, you can use a polyvinyl chloride tube. A piece of tube is placed on a board and, pressing the wire to the tube with the flat of the tip of a well-heated soldering iron, pull the wire through with light force 2-3 times. In this case, the enamel coating is destroyed and the wire is tinning at the same time. The use of rosin is not necessary. Instead of a PVC tube, you can use scraps of installation wire or cable in PVC insulation. Enameled wire of any diameter can be tinned using aspirin-rosin paste. Aspirin and rosin must be crushed into powder and mixed (in a mass ratio of 2: 1). Dilute the resulting mixture with ethyl alcohol to a paste. The end of the wire is immersed in the paste and the tip of a hot soldering iron is passed along the wire with little force or the wire is moved under the tip; the enamel is destroyed and the wire is tinned. To remove residual acetylsalicylic acid (aspirin), the wire is tinned again using clean rosin.
Instead of solder - glue
It is often necessary to solder a wire to a part made of a metal that is difficult to solder: stainless steel, chromium, nickel, aluminum alloys, etc. In such cases, the following method can be used to ensure reliable electrical and mechanical contact. The part where the wire is connected is thoroughly cleaned of dirt and oxides and degreased. The tinned end of the wire is dipped in BF-2 glue and pressed to the junction with the tip of a heated soldering iron for 5-6 s. After cooling, apply 1-2 drops of epoxy glue to the contact area and dry until completely hardened.
Welding instead of soldering
Electric welding significantly reduces the time spent on installation work, produces connections that can withstand high-temperature heating, does not require solders, fluxes, or pre-tinning, and allows you to connect conductors made of metals and alloys that are difficult to solder, for example, the wires of electric heating devices. For welding, you must have a source of direct or alternating current with a voltage of 6-30 V, providing a current of at least 1 A. The electrode for welding is a graphite rod from used KBS batteries or others, sharpened at an angle of 30-40°. As an electrode holder, you can use a probe from an ampere-voltmeter with a crocodile tip. In places of future welding, pre-stripped conductors are twisted into a bundle and connected to one of the poles of the current source. An electrode connected to the other pole of the current source heats up the area to be welded. The molten metal forms a teardrop-shaped compound. As the graphite burns out during operation, the electrode should be sharpened. With the acquisition of skill, welding turns out clean, without scale. It is necessary to work in light-protective glasses.
"Practical advice for an amateur craftsman", 1991. O.G. Verkhovtsev, K.P. Lyutov
Soldering is the joining of parts in a solid heated state using a molten intermediate filler material called solder.
Soldering is widely used in various industries. In mechanical engineering, soldering is used in the manufacture of blades and disks of turbines, pipelines, radiators, fins of air-cooling engines, bicycle frames, industrial vessels, gas equipment, etc. In the electrical industry and instrument making, soldering is in some cases the only possible method of joining parts. Soldering is used in the manufacture of electrical and radio equipment, televisions, electrical machine parts, fuses, etc.
The advantages of soldering include: slight heating of the parts being connected, which preserves the structure and mechanical properties of the metal; purity of the compound, which in most cases does not require further processing; maintaining the dimensions and shapes of the part; connection strength.
Modern methods make it possible to solder carbon, alloy and stainless steels, non-ferrous metals and their alloys.
The quality, strength and operational reliability of a solder joint primarily depend on the correct choice of solder. Not all metals and alloys can act as solders. Solders must have the following properties:
have a melting point lower than the melting point of the materials being soldered;
in the molten state (in the presence of a protective medium, flux or in a vacuum), it is good to wet the soldered material and easily spread over its surface;
ensure sufficiently high adhesion, strength, ductility and tightness of the solder joint;
have a coefficient of thermal expansion close to the coefficient of the soldered material.
As a result of long-term practical selection and numerous scientific studies, groups of solders with an optimal combination of properties were selected.
Depending on the melting point, solders are conventionally divided into two groups: low-melting (soft), having a melting point of up to 500 ° C, and refractory (hard), having a melting point above 500 ° C (Fig. 349).
Low-melting solders are widely used in industries and in everyday life and are an alloy of tin and lead. Different quantitative ratios of tin and lead determine the properties of solders.
Tin-lead solders have a number of advantages over others: high wetting ability, good corrosion resistance. When soldering with these solders, the properties of the metals being joined do not change or hardly change.
Low-melting solders are used for soldering steel, copper, zinc, lead, tin and their alloys, gray cast iron, aluminum, ceramics, glass, etc.
Soldering with fusible solders is used in cases where it is impossible to heat the metal to a high temperature, as well as when there are low demands on the strength of the soldered joint. Connections soldered with low-melting solders are quite airtight.
Low-melting solders are produced in the form of ingots, wire, cast rods, grains, foil strips, tubes (filled with rosin) with a diameter of 2 to 5 mm, as well as in the form of powders and pastes made from powder with flux.
Low-melting solders can also be prepared directly in a workshop or workshop. To do this, melt tin and old solder in metal ladles, then add small pieces of lead and stir well. To prevent the solder from burning out, the surface is sprinkled with crushed charcoal.
To obtain special properties, antimony, bismuth, cadmium, indium, mercury and other metals are added to tin-lead solders.
Tin-lead solders are produced in the following grades:
antimony-free - POS 90, POS 61, POS 40, POS 10, POS 61M and POSK 50-18;
low antimony - POSSU 61-0.5, POSSU 50-0.5, POSSU 40-0.5, POSSU 35-0.5, POSSU 30-0.5, POSSU 25-0.5 and POSSU 18-0.5 ;
antimony - POSSU 95 - 5, POSSU 40-2, POSSU 35-2, POSSU 30-2, POSSU 25 - 2, POSSU 18-2, POSSU 15-2, POSSU 10 - 2, POSSU 8-3, POSSU 5- 1 and POSSU 4-6.
In the brand designation, the letters indicate: POS - tin-lead solder, M - copper, K - potassium; numbers: first - tin content, %, subsequent - copper and potassium content, % (the rest - up to 100% - lead). For plumbing work, POS 40 solder is most often used.
Low-temperature solders are used when soldering thin tin objects, when soldering glass with metal fittings, parts that are especially sensitive to heat, as well as in cases where the solder must act as a temperature fuse (in electrical thermal appliances, etc.).
Refractory (hard) solders are refractory metals and alloys. Of these, copper-zinc and silver solders are widely used. To obtain certain properties and melting points, tin, manganese, aluminum, iron and other metals are added to these alloys.
The addition of small amounts of boron increases the hardness and strength of the solder, but increases the fragility of soldered seams.
Connections soldered with copper and copper-based solders have high corrosion resistance, and most of them can withstand high mechanical loads. The soldering temperature with copper-based solders is 850-1150° C.
These solders are used to produce joints that must be strong at high temperatures, tough, and resistant to fatigue and corrosion. These solders can be used to solder steel, cast iron, copper, nickel and their alloys, as well as other metals and alloys with a high melting point. Hard solders are divided into two main groups: copper-zinc and silver.
According to GOST, copper-zinc solders are produced in three grades: PMTs-36 for soldering brass containing 60 - 68% copper, PMTs-48 - for soldering copper alloys containing copper over 68%; PMC-54 - for soldering bronze, copper, tombac and steel. Copper-zinc solders melt at 700 -950°C.
In the brand, the letter P stands for the word “solder,” MC stands for copper-zinc, and the number stands for the percentage of copper. These solders are supplied in grain form. Solder grains are divided into two classes by size: class A - grains ranging in size from 0.2 to 3 mm, class B - grains ranging in size from 3 to 5 mm.
General information. Soldering is the process of obtaining a permanent connection of materials with heating below the temperature of their autonomous melting by wetting, spreading and filling the gap between them with molten solder and adhesion during crystallization of the seam. Soldering is widely used in various industries.
The advantages of soldering include: slight heating of the connecting parts, which preserves the structure and mechanical properties of the metal; maintaining the dimensions and shapes of the part; connection strength.
Modern methods make it possible to solder carbon, alloy and stainless steels, non-ferrous metals and their alloys.
Solders are the quality, strength and operational reliability of a solder joint. Solders must have the following properties:
have a melting point lower than the melting point of the materials being soldered;
ensure sufficiently high adhesion, strength, ductility and tightness of the solder joint;
have a coefficient of thermal expansion close to the corresponding coefficient of the soldered material.
Low-melting solders are widely used in various industries and households; they are an alloy of tin and lead.
Low-melting solders are used for soldering steel, copper, zinc, lead, tin and their alloys of gray cast iron, aluminum, ceramics, glass, etc. To obtain special properties, antimony, bismuth, cadmium, indium, mercury and other metals are added to tin-lead solders . For plumbing work, POS 40 solder is most often used.
Refractory solders are refractory metals and alloys, of which copper-zinc and silver are widely used.
The addition of small amounts of boron increases the hardness and strength of the solder, but increases the fragility of the soldered seams.
According to GOST, copper-zinc solders are produced in three grades: PMTs-38 for soldering brass with 60...68% copper; PMC-48 - for soldering copper alloys, copper over 68%; PMC-54 - for soldering bronze, copper, tombac and steel. Copper-zinc solders are melted at 700...950 degrees.
Fluxes are used to remove oxide from chemicals. Fluxes improve surface wetting conditions by dissolving oxide films present on the surface of the soldered metal and solder.
There are fluxes for soft and hard solders, as well as for soldering aluminum alloys, stainless steels and cast iron.
Soldering tools. Types of soldered seams
Soldering irons. A special group consists of special-purpose soldering irons: ultrasonic with an ultrasonic frequency generator (UP-21); with arc heating; with vibrating devices, etc.
Periodically heated soldering irons are divided into angular, or hammer, and straight, or end-face. The first ones are used most widely. A soldering iron is a shaped piece of copper mounted on an iron rod with a wooden handle at the end.
Continuous heating soldering irons include gas and gasoline.
Electric soldering irons are widely used because they are simple in design and easy to use. During their operation, no harmful gases are formed, and they heat up quickly - within 2...8 minutes, which improves the quality of soldering. Electric soldering irons are (a) straight and (b) angled.
Types of soldered seams. Depending on the requirements for the products being soldered, soldered seams are divided into three groups:
durable, having a certain mechanical strength, but not necessarily tightness;
dense - continuous sealed seams that do not allow the penetration of any substance;
densely strong, possessing both strength and tightness.
The parts to be connected must fit well together.
Soldering with soft and hard solders
Soldering with soft solders is divided into acid and acid-free. In acid soldering, zinc chloride or commercial hydrochloric acid is used as a flux; in acid-free soldering, fluxes that do not contain acids are used: rosin, turpentine, stearin, solder paste, etc. Acid-free soldering produces a clean seam; After acid soldering, the possibility of corrosion cannot be ruled out.
Brazing is used to obtain strong and heat-resistant seams and is carried out as follows:
surfaces are adjusted to each other by sawing and thoroughly cleaned of dirt, oxide films and fats mechanically or chemically;
the fitted surfaces at the junction are covered with flux; Pieces of solder - copper plates - are placed in place of the solder joint and secured with soft knitting wire; the prepared parts are heated with a blowtorch;
when the solder melts, the part is removed from the heat and kept in such a position that the solder cannot flow from the seam;
then the part is slowly cooled (it is impossible to cool a part with a soldered plate in water, as this will weaken the strength of the connection).
Safety. When soldering and tinning, the following safety rules must be observed:
The soldering workplace must be equipped with local ventilation (air velocity of at least 0.6 m/s);
work in gas-polluted areas is not allowed;
After finishing work and eating, you should wash your hands thoroughly with soap;
sulfuric acid should be stored in glass bottles with ground stoppers; You need to use only diluted acid;
When heating the soldering iron, you should follow the general rules for safe handling of the heating source;
For an electric soldering iron, the handle must be dry and non-conductive.
Coating the surface of metal products with a thin layer of an alloy (tin, tin-lead alloy, etc.) appropriate for the purpose of the product is called tinning.
Tinning is usually used when preparing parts for soldering, as well as to protect products from corrosion and oxidation.
The tinning process consists of preparing the surface, preparing the plating and applying it to the surface.
Preparing the surface for tinning depends on the requirements for the products and the method of applying the plating. Before tin coating, the surface is brushed, polished, degreased and etched.
Irregularities on products are removed by grinding with abrasive wheels and sandpaper.
Fatty substances are removed with Vienna lime, mineral oils with gasoline, kerosene and other solvents.
Tinning methods. Tinning is carried out in two ways - immersion in half (small products) and grinding (large products).
Immersion tinning is carried out in a clean metal container, in which the semi-dish is placed and then melted, pouring small pieces of charcoal onto the surface to protect it from oxidation. The product is then washed in water and dried in sawdust.
Tinning by rubbing is performed by first applying zinc chloride to the cleaned area with a hair brush or tow. Then the surface of the product is uniformly heated to the melting temperature of the half-plate, which is applied from the rod. After this, they are heated and other places are served in the same order. At the end of tinning, the cooled product is washed with water and dried.
Gluing
General information. Bonding is the process of joining machine parts, building structures and other products using adhesives.
Adhesive joints have sufficient tightness, water and oil resistance, and high resistance to vibration and shock loads. In many cases, gluing can replace soldering, riveting, welding, and interference fit.
Reliable connection of parts of small thickness is possible, as a rule, only by gluing.
Adhesives. There are several types of BF glue, produced under the brands BF-2, BF-4, BF-6, etc.
Universal adhesive BF-2 is used for gluing metals, glass, porcelain, bakelite, textolite and other materials.
BF-4 and BF-6 glues are used to obtain an elastic seam when joining fabrics, rubber, and felt. Compared to other adhesives, they have little strength.
Carbinol glue can be liquid or paste-like (with filler). The adhesive is suitable for joining steel, cast iron, aluminum, porcelain, ebonite and plastics and provides bonding strength within 3-5 hours after preparation.
Bakelite varnish is a solution of resins in ethyl alcohol. Used for gluing linings on clutch discs.
The technological process of gluing, regardless of the materials being bonded and brands of adhesives, consists of the following stages: preparing surfaces for gluing - mutual preparation, cleaning from dust and grease and imparting the necessary roughness; applying glue with a brush, spatula, spray bottle; hardening of glue and quality control of adhesive joints.
Defects. Reasons for the weakness of adhesive joints:
poor cleaning of bonded surfaces;
uneven application of the layer on the bonded surfaces;
hardening of the glue applied to the surface before joining;
insufficient pressure on the connecting parts of the parts being glued;
incorrect temperature conditions and insufficient drying time for the adhesive joint.
Description of the presentation by individual slides:
1 slide
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2 slide
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Soldering is the joining of parts in a heated state using a relatively low-melting metal called solder. Soldering is widely used in various industries to create permanent connections of various workpieces and parts made of steel, non-ferrous metals and their alloys, as well as dissimilar metals. Soldering is used in the manufacture of radio and electrical devices, tanks, radio products, carbide cutting tools, etc. The essence of soldering is that molten solder, under the action of capillary forces, fills the gap between the soldered surfaces of the parts, wets them and diffuses (penetrates) into the metal. After the solder cools, a dense and fairly strong connection is formed in the area of contact between the parts, called a solder seam. The quality, strength and operational reliability of a soldered joint depends on the correct choice of solder and the thorough preparation of the surfaces to be connected for soldering.
3 slide
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To clean surfaces, sanding with files, metal brushes, sandpaper, etc. is used. Parts obtained by cutting (dry) are soldered without additional cleaning. If oil or emulsion was used during mechanical or metalworking processing, they are removed before soldering by degreasing in gasoline, acetone and other substances. Before soldering, the parts are tightly fitted to one another. When parts connected by soldering are heated, their surfaces are oxidized (covered with a thin film), as a result of which the solder does not stick to the parts. To remove the oxide film, soldering fluxes are used, which dissolve oxides, form easily removable slags, and promote better wetting of the soldered surfaces with molten solder and its flow into the gaps. For low-melting solders, the following fluxes are used: zinc chloride (etched hydrochloric acid), ammonia (ammonium chloride) and rosin. For refractory solders, boric acid and borax are used. When soldering cast iron, aluminum, and stainless steels, various flux compositions are used.
4 slide
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5 slide
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The most common tools for soldering are intermittent and continuous heating soldering irons. Hammer and end-type intermittent heating soldering irons are made from a piece of high-quality red copper of a prismatic wedge shape, mounted on a steel rod with a wooden handle at the end. Such a soldering iron is periodically heated from an external heat source - a forge, a blowtorch, a gas burner flame, etc.
6 slide
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Blowtorches are most often used for heating. 1 - air supply tube; 2 - reservoir; 3 - airspace; 4 - heating bowl; 5 - channels; 6 - pipe; 7 - mixer; 8 - nozzle; 9 – windproof device; 10 - valve; 11 - cover; 12 – pump.
7 slide
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Continuous heating soldering irons include electric soldering irons that allow for continuous soldering. They are easy to use, provide a constant temperature, and produce less harmful gases during operation. a - straight: 1 - electrical cord; 2 - electrical plug; 3 - working part; 4, 7 - clamps; 5 - casing; 6 - heating element; 8 - rod; 9 - handle; b - angular Electric soldering irons
8 slide
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a - gas; b - gasoline; 1 – working part; 2 - rod; 3 - clamp; 4 - burner; 5, 9 - taps; 6 - handle; 7, 8 - fittings; 10 - nozzle; 11 – gasoline burner; 12 – handle reservoir Continuous soldering irons
Slide 9
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Tinning is the process of coating the surfaces of metal parts with a thin layer of molten tin or tin-lead alloys (solders). Tinning is carried out in order to protect parts from corrosion and oxidation, to prepare the surfaces of connected parts for soldering with low-melting solders, before filling bearings with babbitt and in cases where tightness is required from the manufactured vessel. Tinning of surfaces is carried out using hot and electric methods. Hot tinning, due to its simplicity, ease of execution and uncomplicated equipment, is widely used in metalworking.
10 slide
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SOLDERING TECHNIQUES WITH LOW-FUSE SOLDERS After preparing the soldered surfaces of the parts, their adjustment and fastening, soldering begins. The gaps between parts should not exceed 0.05...0.15 mm for steel and 0.1...0.3 mm for copper. When using a periodically heated soldering iron, its tip is cleaned of traces of scale with a file, tucked at an angle of 30...400, burrs are removed, slightly rounding the edge of the tip. A protected soldering iron is heated with a blowtorch or other heat source to 350...4000C for soldering large parts and up to 250...3000C for soldering small parts and sheet material. Heat the working part (butt) of the soldering iron. Heating the soldering iron is best done with a kerosene blowtorch.
11 slide
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To light the lamp, you need to pour a little gasoline into tray 3 and set it on fire. Before lighting the lamp, valve 4 is closed and air valve 2 is opened. By the time gasoline is completely burned in bath 3, you should close valve 2, pump air into tank 1, open valve 4 slightly and place the lamp near the protective device (or brick) at a distance of 10...15 cm, heat the lamp coil with a low flame, and then adjust the burning intensity. Extinguish the lamp by closing valve 4 and releasing air from tank 1 with valve 2. If the lamp nipple becomes clogged, clean it with a Primus needle.
12 slide
Slide description:
To heat up, the soldering iron is placed in a special device (a), making sure that its working part (shank) is in the non-smoking zone of the flame. During breaks between soldering, the heated soldering iron is placed on a stand bent from a steel rod (b).
Slide 13
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Techniques for preparing a soldering iron for use with low-melting solder are shown in the figure, a...c. The heated soldering iron is first cleaned of scale by immersion in zinc chloride or ammonia (a), then the working part of the soldering iron toe is tinned, for which, with a soldering iron cleaned in zinc chloride, one or two drops of solder are taken from the rod (b) and rubbing (reciprocating) is performed. movements along the lump ammonia until the toe is covered with an even layer of solder (c). Then the joint is etched, for which a solution of zinc chloride or another flux is applied with a brush. After this, the soldering iron is placed on the soldering site, where the molten solder flows from the soldering iron and fills the gaps between the parts. If the solder does not spread over the surface, does not flow over the surface and does not flow into the gap, then the soldering area must be coated with flux again and the soldering operation must be repeated. The speed of movement of the soldering iron along the soldered seam, or the heating speed, depends on the mass of the soldering iron, the temperature of its heating and the mass (thickness) of the parts being soldered.
14 slide
Slide description:
SOLDERING TECHNIQUES WITH HIGH FUSE SOLDER a - etching the soldering area with flux (zinc chloride); b - applying solder and moving the soldering iron along the seam; c - butt soldering; g - overlap soldering; d - soldering a thick plate to a thin one; e - pipe soldering; g - soldering thick wires and rods
15 slide
Slide description:
If the solder does not fill the seam gap, but drags behind the soldering iron or turns into a mushy mass, then the soldering iron has cooled down or is not heated enough. Overheating of the soldering iron leads to increased scaling and worsening of tinning of the tip. Often, before soldering, to ensure reliable adhesion of the solder, pre-tinning of the junction surfaces is used, for which these surfaces are coated with a thin layer of solder or tin. After soldering the resulting seam, remove flux residues by washing the part in running water, then in an aqueous solution of caustic soda, again in running water and dry. Soldering control is carried out by external inspection of the seam for tightness (leakage of a welded vessel filled with water is not allowed) and strength (the part bent at the weld site should not have cracks). When soldering parts made of copper and its alloys, including wire, the best flux is rosin.
16 slide
Slide description:
Soldering techniques with medium-melting and high-melting solders Preparation of parts for soldering with high-melting solders is the same as for soldering with low-melting solders. After cleaning the surfaces and applying flux (borax), solder in the form of powder, tape, plates, etc. is introduced into the gaps, then fastened with soft wire so that the parts being connected do not move. After such preparation, the part is carefully introduced into the flame zone of a blowtorch, gas burner, forge, into the inductor of the HDTV installation and the process of solder melting is monitored. Initially, the heating of the junction should be carried out slowly with a shutter speed of up to 5 minutes at each stage. When the swollen borax settles, the heating is increased and continued until the solder completely melts and fills the gaps between the parts being connected. Upon completion of soldering, the part is slowly cooled, the seam is protected from excess deposited and leaking solder, then washed and dried.
Slide 17
Slide description:
The work methods are as follows: before soldering the plate, the junction area is degreased and coated with flux; a thin plate of sheet brass solder is placed on the cutter holder, which has a groove (socket) for the carbide plate; then a carbide plate is placed in the groove and everything is connected (tied) with a thin knitting wire (a), the soldering area is sprinkled with borax and heated in a forge (b) or another heat source until the borax powder melts (650...7000C), then it is applied again portion of borax and continue heating until the solder melts (850....9000C), which should fill the gap between the soldered parts.
18 slide
Slide description:
TINING BY RUNNING AND IMMERSION When tinning by rubbing, the part is cleaned with a file, scraper or sandpaper to a uniform metallic shine, then washed for 1...2 minutes in a boiling 10% solution of caustic soda in hot water. Immediately before tinning the surface, the parts are coated with flux (zinc chloride) using a hair brush, felt or tow and sprinkled with ammonia powder on top, then heated to the melting temperature of tin so that the solder applied to the part - tin or other alloy in the form of small pieces or powder - melts and spread over the surface.
Lead-tin solders (POS.)
The use of lead-tin solders can only give good results when the worker correctly understands the soldering process and knows the basic rules of work. Depending on the purpose of the parts or products being soldered, soldering seams are divided into: strong seams (must withstand mechanical loads); tight seams (should not allow liquids or gases under low pressure to pass through); strong and tight seams (must withstand the pressure of liquids and gases under high pressure).
During the soldering process, as a result of wetting, solder forms an intermediate alloy zone with the surface of the part being soldered, and the quality of soldering in this case, in the presence of clean metal surfaces, will depend on the rate of dissolution of a given metal in the solder: the higher the dissolution rate, the better the quality of soldering. In other words, the quality of soldering depends on the diffusion rate. The increase in the degree of diffusion is facilitated by: the presence of clean metal surfaces of the parts being soldered. With an oxidized surface, the degree of solder diffusion is significantly reduced or completely absent; preventing oxidation of the molten solder during the soldering process, for which appropriate soldering fluxes are used; soldering at a temperature close to the melting point of the part being soldered; slow cooling after soldering (in hot sand, hot coals). It has been noticed that when soldering parts galvanically coated with other metals, the seam is not as strong as when soldering pure metals or alloys. This is observed with all galvanic coatings (nickel, chromium, tin, cadmium). On the contrary, soldering over hot tinning with tin or tin-lead alloys always gives a stronger connection than over pure metal. This example confirms the influence of the degree of diffusion on the strength of the weld during soldering.
Tinning- the process of coating metal surfaces with tin or a special tin-based alloy (poludoy).
Solder- a metal or alloy that serves to join in a molten state, in the gap (seam) between parts, therefore the solder must have a lower melting point than the metals being joined.
Based on their composition, solders are divided into several groups, of which the most important is tin-lead solders.
Solder compositions.
Often, due to the lack of information about solders, the worker always has a tendency to use solders with a high tin content, although this is not always necessary. The correct choice of solder can only be guaranteed when its properties are known.
In table Table 1 shows the compositions of the most well-known tin-lead solders.
Purpose of solders.
POS 90 - for soldering internal seams of food utensils (pots, etc.).
POS 40 - soldering of brass, iron and copper wires.
POS 30 - soldering of brass, copper, iron, zinc and galvanized sheets, tinplate, instruments, radio equipment, flexible hoses and banding wire for electric motors.
POS 18 - soldering of lead, iron, brass, copper, galvanized iron, tinning of wood before soldering, substitute for POS 40 solder.
POSS 4-6 - soldering of tinplate, iron, copper, lead in the presence of riveted key seams, substitute for POS 30 solder.
Table 1 Compositions of tin-lead solders:
Properties of tin-lead solders.
In table 2 shows the properties of tin-lead solders in comparison with pure metals - lead and tin. The most important property of solders is shear resistance, since most solder joints are shear-resistant.
Tin-lead solders of the POS 18, POS 30, POS 40 brands have higher shear resistance than pure tin and lead, and therefore their use to obtain a strong seam gives better results.
Solders must have both high tensile strength and maximum toughness. According to the table, it is possible to establish the interchangeability of high-tin and low-tin solders. For example, POS 18 solder is slightly better in terms of viscosity than POS 40 solder, and differs slightly from the latter in strength. POS 50 solder can easily be replaced by POS 40 and POS 30 solder. Knowledge of hardness is important in the sense that harder solders resist abrasion better than soft ones.
Therefore, all the advantages in this regard will be for POSS 4 - 6 solder. The remaining solders (POS 18, POS 30 and POS 40) have a slightly lower hardness. Impact strength (impact resistance) is of greatest importance for pure tin, but POS 40 and POS 30 solder differs little from tin in this regard. Therefore, POS 40 solder can be used in special cases where soldering points are subject to strong vibration. For normal operating conditions, with minor vibrations, POS 18 solder is used.
The melting temperature of the solder is also of great importance: the choice of soldering method depends on it. POS 62 solder, containing 62% tin, has the lowest melting point. This solder is used in cases where parts cannot be overheated during soldering, for example, when connecting very thin wires. The possibility of using ternary low-melting alloys in such cases, in which
Table 1 Properties of tin-lead solders
The low melting point achieved by adding a third component (for example, bismuth) is excluded due to the fact that ternary alloys do not have such high viscosity as binary alloys. NOS 62 solder is now rarely used, since overheating during soldering can be easily avoided by using POS 40 solder of a very thin section, for example in the form of wire with a diameter of 1-2 mm. Under the action of a soldering iron, thin wire melts quickly, as a result of which the time of exposure to high temperature is reduced to a minimum.
Practice has shown that POSS 4-6 grade solder in terms of soldering strength is equivalent to POS 30 grade solder for all materials except galvanized iron and copper. At the same time, solder of the POS 40 brand in most cases has the greatest strength and in this respect is superior to high-tin solder of the POS 62 brand and pure tin. Therefore, to obtain the greatest strength of the weld, pure tin should never be used.
POS 18 brand solder, when butt soldering, gives higher adhesion strength than POS 40 brand solder. Therefore, POS 18 solder is used when the melting temperature of the solder is not critical.
Soldering technological process.
To obtain the best results, the soldering process should consist of the following operations:
mechanical (scraper, file, sandpaper) or chemical cleaning; flux coatings; heating (soldering iron, blowtorch, forge); pre-tinning with solder (with a soldering iron, or rubbing, or immersion in solder); fastening places for soldering, coating them with flux and heating; 63introducing solder, melting it and removing excess solder, as well as flux residues.
The surfaces to be soldered are cleaned of oxides with a file or scraper so that the gap between the two surfaces is the same everywhere and does not exceed 0.1-0.3 mm. Such a small gap is necessary for the formation of capillary forces, which contribute to the suction of solder to a significant depth from the edge. If the surfaces to be soldered have traces of fat or oil, then they are treated with a hot alkali solution. Usually they take a 10% soda solution. If it is impossible to mechanically clean the parts for any reason, then etching of the parts in acids is used. Typically, a 10% solution of sulfuric acid is used for copper and its alloys, and for parts made of ferrous metals, a 10% solution of hydrochloric acid is used, and the solution must be heated to 50-70 °C.
After cleaning and preparing the parts, the soldering points should be tinned. Pre-tinning is very important, since in this case increased strength and density of the joint are achieved. If pre-tinning is not possible, soldering can also be done on a clean surface, but the results, of course, will be lower.
For preliminary tinning, the same solder is used as for subsequent soldering. If, for example, soldering is performed with POS 30 grade solder, then preliminary tinning should be carried out with the same solder.
Before soldering, the parts are fastened so that the joints do not diverge under minor mechanical stress, for example when applying a soldering iron. The simplest way of fastening is tying with soft wire, preferably iron, but, of course, other methods are not excluded, for example, compression with clamps, bending the seam to form a “lock”.
The soldering method depends greatly on the type of solder used. The most typical cases of soldering:
soldering iron using soft solders;
hand blowtorch usually using hard solders;
electrical soldering (the junction serves as a resistance; a low voltage current is passed through the resistance).
When soldering with a soldering iron, solders are usually used whose melting point is not higher than the melting point of lead (327°C). Such soldering is performed when the parts are not subjected to heavy loads or require further soldering. If parts are heated to high temperatures during operation, soldering with a soldering iron using soft solders is excluded.
Preparing the soldering iron for work are carried out simultaneously with the preparation of parts. The soldering iron is lightly forged (partially to remove carbon deposits and oxides), clamped in a vice and filed so that its working part is semicircular. If you file a soldering iron without first forging it, it will soon wear out. The end of the soldering iron is made semicircular because in this case it does not cool as quickly as a sharp one, it warms up the soldering areas better and is corroded more evenly by liquid solder.
After mechanical preparation, the soldering iron is tinned, for which it is heated no higher than 400 ° C, the end of the soldering iron is dipped into an aqueous solution of zinc chloride, after which the hot soldering iron is rubbed against a piece of solder until the entire working part is covered with a layer of poluda.
During operation, the soldering iron must have a temperature that satisfies the following requirement: if the soldering iron is applied with a working place to a solder bar, the part of the solder adjacent to the soldering iron should melt in 0.5-1 s. During operation, the temperature of the soldering iron should be such that the solder flakes or drops of solder adhering to the soldering iron are in a liquid state.
A more convenient way to service a soldering iron is as follows: make small indentations in a piece of ammonia (ammonium chloride) and place pieces of solder there. As you move the hot soldering iron back and forth across the solid ammonia, you simultaneously touch the solder. This way the soldering iron is tinned faster.
If you touch the seam with a heated soldering iron and at the same time place a piece of solder in the form of a rod, tape or wire on the seam, the solder will melt and penetrate into the seam. Excess solder is smoothed along the seam with a soldering iron. Solder is also applied to the seam with a soldering iron, since drops of solder always stick to the soldering iron, and if the tip of the soldering iron is passed along the seam, liquid solder is sucked into the seam. In order for new drops of solder to transfer to the soldering iron, it is again taken away from the seam and applied to a piece of solder.
Tinning.
The technological process of tinning consists of the following operations:
cleaning the surface from foreign substances with a wire brush, sand, lime or sandpaper;
degreasing with gasoline or a hot aqueous solution of soda or caustic soda;
washing in water;
chemical cleaning from etching oxides in acids;
coating with fluxes (zinc chloride) by brush or immersion in an aqueous solution of flux;
heating to the melting temperature of semi-plate and tinning.
They tin small objects with a soldering iron; if necessary, the working part of the soldering iron is tinned into the shape of the object being tinned (for example, a semicircle when tinning tubes and wire).
Tinning of large objects - tanks and other containers - is carried out by the rubbing method. To do this, the product is moistened with a solution of zinc chloride and heated (on a forge, coals, etc.) to the melting point of tin, after which it is sprinkled with a powdered mixture of tin and ammonium chloride (ammonia). At the same time, the tin melts and, ground with tow, forms an even layer of poluda on the surface. After tinning, flux residues are washed off with hot water.
When tinning food utensils, the old half is checked for lead content, for which part of the tinned surface is moistened with a 10-15% solution of acetic acid. After 2-3 minutes, apply 5-6 drops of an 8-10% solution of potassium iodide to the same place, add water and rub both solutions over the surface. If there is lead in the solution, a characteristic yellow color of the solution appears on the wetted surface. If lead is detected, the surface of the product is etched with a mixture of nitric and hydrochloric acids or cleaned with a sandblaster until the half-lead is completely removed.
Soldering methods.
Some metals or alloys require special soldering techniques.
Lead. When heated, lead oxidizes so quickly that soldering must be carried out in a reducing atmosphere, which protects the soldered areas from oxidation and allows the solder to easily connect to the base metal. A reducing atmosphere is formed as a result of using a burner for heating, into which hydrogen and air oxygen are supplied, and hydrogen should always be in excess. Lead is used as solder.
The use of lead-tin solders is undesirable, since the seam then begins to corrode in acids.
Zinc. For soldering zinc, conventional lead-tin solders are used. We recommend using POS 30 solder mixed with chloride flux.
If the zinc is pure, then when soldering it, a saturated solution of zinc chloride or dilute hydrochloric acid is usually used. If contaminated zinc or a zinc alloy is soldered, then when hydrochloric acid is used as a flux, a black deposit forms at the etching site (therefore, it is recommended to use hydrochloric acid with ammonium chloride).
Note that double fluxes protect metal from corrosion to a greater extent than ordinary flux. When soldering with lead-tin solders, it is better to use a flux containing ammonium chloride and a saturated solution of zinc chloride, taken in a ratio of 1:5 (by weight). For tin-cadmium solders, it is recommended to use caustic soda as a flux. When soldering zinc alloys containing more than 2% aluminum (parts made by injection molding), the same methods are used as when soldering aluminum or alloys. In this case, tin-zinc solders are used, and hydrochloric acid, petroleum jelly or stearin are used as fluxes. Sometimes a flux consisting of 85% stearic acid and 15% sodium chloride is used.
Cast iron. To solder a crack or other defect in a cast iron part with soft solder, thoroughly mechanically clean the soldering area and moisten it well with hydrochloric acid. Then this place is treated with an aqueous solution of zinc chloride, sprinkled with ammonia (ammonium chloride) powder and heated with a soldering iron or blowtorch. It is necessary to heat the soldering area until the solder brought to it begins to melt. Then rub solder on the joint and immediately wipe it with ammonia powder applied to a thick metal brush or tow. This operation is preliminary tinning before soldering. While the part is still hot, solder cracks or other defects with a soldering iron, moving it from one end of the crack to the other. If the solder does not penetrate into the crack, you need to use a sharp chisel to remove a small chamfer from both edges, tin this place and perform soldering again. Excess solder is removed with a scraper or file.
Soldering metals to glass, quartz, porcelain. When soldering metal to glass and other similar materials, it is necessary to galvanically deposit a layer of metal at the soldering site and then perform soldering in the usual way.
Soldering glass products to metal (for example, when connecting glass tubes with metal flanges, etc.) is done as follows: first, the surface of the glass is ground with sandpaper, then graphite is rubbed into the rough surface with a rag, and copper is deposited in this place in an electroplating bath. Next is soldering and secondary deposition of copper (or nickel).
Quartz. The quartz part is thoroughly cleaned and degreased by successive washing in nitric acid, alkali and water. A layer of silver is applied to the cleaned part using two solutions (the content of components is given in grams).
Solution 1 (silver)
Water 200
Silver nitrate 2
Ammonia until sediment dissolves
Solution 2 (reducing)
Water 1000
Silver nitrate 10
Rochelle salt 3.3
Refined sugar 3.3
Solutions 1 and 2 are poured together and applied to the surface of the part in such a way that the entire area to be silvered is covered with the solution. Immediately before silvering, the part should be processed for 1-2 minutes. 1% solution of stannous chloride and rinse with distilled water. The silvering process lasts 20-30 minutes until a golden-colored sediment is obtained. The silver-plated part is rinsed and dried at 50-70 °C. After drying, a copper layer of the required thickness is electrolytically grown on the resulting silver layer from an acidic copper bath. Silver plating and copper plating are done on porcelain in the same way.
Aluminum. To solder aluminum, put a corrugated tip on the soldering iron (its working part is sawn with a triangular file). The nozzle is made of U-7 steel and hardened so that the teeth do not work together. The nozzle is turned on a lathe and its end is sawed off. The nozzle tube is sawed into four parts with a hacksaw, this creates springiness of the nozzle, and it is tightly inserted into the working part of a regular soldering iron. The diameter of the hole in the nozzle is drilled in accordance with the diameter of the working end of the soldering iron.
The welding areas are thoroughly cleaned until shiny, melted rosin is taken onto the teeth of the nozzle and applied to the soldered area. When the rosin begins to cover the aluminum during the tinning process, the soldering iron is moved back and forth in short movements, and the teeth will scrape the metal. Using this method, the entire surface of the joint is cleaned, after which the cleaned areas are tinned. Then they start soldering. To do this, take a drop of tin, previously sprinkled with rosin, on a soldering iron and bring it to the tinned area. If the tinned area is rough, then use a soldering iron to remove this roughness, which is porous tin mixed with particles of aluminum oxide formed due to a lack of flux. First, rosin is poured onto the soldered joint, a drop of tin is taken on the soldering iron and applied to the seam to be soldered. As soon as the tin wets the joint, the soldering iron is removed from the metal. Then soldering is performed a second time; for this, the soldering area is again sprinkled with rosin.
When soldering aluminum, especially during the tinning process, the soldering iron should be warmed up well and kept in one place for a long time and, after heating the metal, slowly move along the seam to be soldered.
For soldering aluminum alloys, POS 50 and POS 90 solders are recommended. The flux is mineral oil (weapons oil is especially recommended). First, flux is applied to the seams to be soldered and then the soldering areas are cleaned. Soldering is carried out with a powerful, well-heated soldering iron. Before starting soldering, the metal should be warmed up well. For soldering aluminum alloys, a special P250A solder is also produced; it consists of 80% tin and 20% zinc. The flux is a mixture of lithium iodide (2.-3g) and oleic acid (20 g). Before use, the soldering iron must be tinned with the specified solder using rosin. The surfaces to be soldered are cleaned of flux residues with a gauze swab soaked in acetone.
Soldering products with thin seams.
To solder such products (for example, chains, rings or other jewelry), a special solder is used, consisting of a mixture of equal parts - boric acid, zinc (fine zinc), copper, phosphorus, which is mixed with castor oil. The products are dipped into this solder and the solder penetrates into the joint of the product. Then the products are sprinkled with talc to remove excess solder remaining on the surface of the product, after which the product is intensively heated on a gas burner at a temperature of 1000°C. When heated quickly, the solder produces a microflash, and the temperature rises to 1200 °C.
Hard soldering. For soldering products made of copper and brass, when soldering the most critical seams, hard solders consisting of an alloy of copper and zinc are used. Such solders include brass grade L-63, which contains copper from 62 to 65%, the rest zinc, as well as solders containing copper - 51%, zinc - 44% and tin - 5%. The addition of tin gives the solder plasticity and improves spreadability over the metal. The melting point of solder L is 63-950 °C, solder with tin is 860 °C. For soldering thin products, solders in the form of sawdust are used; for one part of the solder, one part of the flux is taken - calcined borax. Soldering is carried out in a stream of flame from a blowtorch,
Fluxes. When soldering, fluxes play the role of chemical solvents and oxide absorbers. During the soldering process, they protect the metal from oxidation and create conditions for wetting the metal with solder. When working with lead-tin solders, hydrochloric acid, zinc chloride, boric acid, borax, ammonium chloride, etc. are used as fluxes. Fluxes that do not produce a chemical effect include: rosin, wax, petroleum jelly, olive oil, etc. These fluxes form a coating on the surface of the metal that protects it from oxidation.
Solution of hydrochloric acid They use lead-tin and other soft solders when soldering.
Zinc chloride- a good fluxing agent for soldering brass, copper, iron and other metals and alloys. To prepare zinc chloride, cut the zinc into small pieces, “dissolve” it in hydrochloric acid, and then the prepared zinc chloride is diluted with an equal volume of water.
Ammonia(ammonium chloride) dissolves fatty substances well.
Buru used both in dissolved and solid form. Instead of borax, you can also use glass powder. Liquid glass is also used as a flux.
Flux for soldering aluminum consists of tung oil, rosin and calcined zinc chloride, taken in a ratio of 3:2:1 (by weight). To remove oxides on aluminum during soldering, fine steel filings are used, which remove the resulting oxide during the soldering process.
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