The procedure for using cold welding for joining metals and alloys

Modern adhesives can work perfectly in the most extreme conditions. Some tools can even connect metal products, fill cracks and chips. For example, cold welding for metal is used in everyday life and industry, allowing repairs of any complexity.

Content:

• Features, advantages and disadvantages of cold welding
• Types of welding
• Specifications and Composition
• Manufacturers
• Area of ​​use of welding
• Cold welding selection criteria
• Temperature mode
• Sealants
• Compositions for cars
• Filling value
• Instruction for use
• The main rules of work
• Precautionary measures

Features, advantages and disadvantages of cold welding

Cold welding is called two-component epoxy-based adhesives. Before mixing the components, the product can be stored for a long time, but after combining the base and hardener, a chemical reaction immediately begins, and, literally in 10-20 minutes, the mass hardens. The glue is capable of destroying the oxide film that is present on the surface of the metal, so the parts reliably fit together with the formation of new intermolecular bonds.

The chemical welding method is effective where conventional welding is difficult for a number of reasons. It is suitable not only for ferrous metals, but also for non-ferrous (aluminum, copper, alloys), plastic. This method is ideal for surfaces sensitive to heat, because it does not require the use of argon. Also, cold welding is useful when working in hazardous conditions, where there is a high risk of explosion, fire.

Features and advantages of cold welding are as follows:

• speed of action, lack of need for skills, special knowledge, use of equipment;
• the availability of formulations by availability in stores and price;
• lack of deformation of parts, complete preservation of the initial properties of the metal;
• reliability of the weld, its aesthetic appearance.

The technology of cold welding of metals eliminates the appearance of waste, is safe, and after drying, the weld is absolutely harmless to health. But the method also has disadvantages. The life of repaired products is still lower than those that were hot-welded. Cold welding will not be able to reliably close up large defects, it can only serve as a measure of emergency assistance. The adhesion quality of parts will deteriorate sharply without the proper preparation - cleaning, degreasing.

Types of welding

Cold welding can be carried out in different ways, depending on the type of work surface, the position of the future seam. Here are the main types of welding:

• Point - the connection is formed by selective pressure on the surface. Between points a certain interval is observed.
• Suture - as a result of fixing the parts, a continuous seam is created. The method is suitable for bonding device cases, equipment, sealed containers.
• Butt - it can be used for the production of rings, docking wires.
• T-shaped - allows you to glue parts located at right angles.
• Shear welding - helps to obtain a reliable continuous seam, characterized by tightness. The method is preferably used for piping, heating systems.

Also, cold welding products vary in consistency.They are thick, looking reminiscent of plasticine, consist of two bars. The application technology is based on mixing the components, as a result of which an adhesive mass is formed. The second option is cold welding - liquid means, for their preparation for work two fluid substances are mixed - resin and hardener. In everyday life, it is much more convenient to use plasticine-like products.

There is another classification according to which welding differs in purpose and technical characteristics:

• waterproof - can be used to repair plumbing, pipes, does not deteriorate from contact with water (some compounds glue defects directly in the water);
• automotive - this material contains a small metal filler and is intended for the repair of vehicles (bumpers, various systems and interior elements);
• universal - with this tool it is possible to glue almost all types of surfaces, even wooden, polymer, according to user requests this product is the most popular;
• high-temperature - the product is heat-resistant, allows repaired products to work at extremely high temperatures (up to +1300 degrees);
• with high adhesion indicators - the product contains cast iron chips or other modern fillers that seriously improve the adhesion quality.

Specifications and Composition

Any cold welding is carried out in accordance with technical standards and requirements. Its main component is a polymeric substance - epoxy resin, which provides the binding of materials to each other. Iron, aluminum, cast iron dust is responsible for the strength of bonds, it also makes the tool resistant to temperature (high and low). Other additives are introduced into the composition by the manufacturer, depending on the formulation, it may be sulfur, other minerals.

The average technical parameters of welding are as follows:

• primary drying - 5-20 minutes;
• final drying - 3-24 hours;
• operating temperature - up to + 130 ... + 1316 degrees.

Many materials withstand a fairly large tensile force (up to 9.5-10.5 MPa), shear (438 N and above). Most welds reliably withstand shear stress (average 4.04 MPa).

Manufacturers

Domestic welding brands are not inferior in quality to imported ones, although their price is an order of magnitude lower. The funds of the companies Almaz, Polymett have proven themselves excellently. Of foreign brands, the following are popular:

• Hi-Gear quick steel - suitable for ferrous and non-ferrous metals, stone, plastic, resistant to physical and chemical effects;
• Super Epoxy Henkel Moment - retains properties up to +260 degrees, suitable for all materials;
• Poxipol Cold welding - creates a very durable seam that cannot be torn, is moisture resistant;
• Wurth Liuguid Metal is an absolutely non-combustible agent resistant to any aggressive substances;
• Mastix - suitable even for pipes under pressure, batteries and radiators, easily closes any defects.

Area of ​​use of welding

The instructions for use usually indicate the area where you can operate a particular composition. Welds designed for metal are perfect for all types of metal products, including:

• for energized (power supplies, wires, other parts);
• in contact with liquids (water, alkalis, oils, for example, radiators or gas tanks of a car).

The most widely used welding is in the repair of cars, other vehicles, for plumbing (heating, sewage, water supply). Also, the material is popular in everyday life, repair of instruments and equipment, electronic devices and equipment. Due to its versatility, metal products are also suitable for the restoration and gluing of carpet and linoleum, ceramic, glass and plastic products.

Cold welding selection criteria

The first thing they pay attention to is whether the material is suitable for the field of application. To repair complex metal structures and vibration-prone joints, you only need to use tools that have adhesion promoters in the composition.There are other parameters that are studied when buying cold welding.

Temperature mode

What temperature a welding can withstand depends on its composition and production characteristics. Raising temperatures to +130 degrees perfectly tolerates most products. For inexpensive formulations, the maximum operating threshold is + 260 ... + 275 degrees, as always indicated on the package. But even such temperatures can be tolerated only with strict adherence to gluing technology, otherwise the threshold decreases.

For special cases (for surfaces exposed to heat and open flame) special heat-resistant compounds are implemented. They withstand up to +1316 degrees and retain high tensile strength. One of the best heat-resistant welds can be called Thermo from Kerry, it is used to repair mufflers and can work at -60 ... + 900 degrees.

Sealants

If it is necessary to seal the weld, a composition with sealant properties should be selected. Typically, such welds are used to repair plumbing and heating, many of them are used under water for emergency repair of leaks. They do not have high breaking requirements for such products; their main property is to serve as a sealant in the event of a defect.

Compositions for cars

Automotive cold welding must meet a number of characteristics for durability:

• to temperature changes;
• to vibration;
• to the action of aggressive chemistry, oxidizing agents.

The tear-off strength of such materials is high, and the technical characteristics are medium in terms of tightness, as well as in water resistance. The form of release is usually plastic-shaped, because from welding sometimes it is necessary to literally fashion patches, rivets, even the likeness of bolts, on which you can then thread. Sometimes automobile weldings are used as putty for repairing a bumper, but more often they serve as a temporary means for sealing up a damaged radiator, silencer, gas tank.

Filling value

In order to glue the metal in a quality manner, a metal filler must be present in the composition of the welding - it is he who makes the weld bead as strong as the main product. Ideally, if it is identical to the material of the part itself. When there is no such product on sale, you can take one where the filler is more powerful (for example, cast iron powder is suitable for gluing steel).

Instruction for use

Before starting work, you need to clean the glued parts in a quality manner. To do this, remove all non-fixed elements, remove grease and any impurities, remove even the smallest particles of dust. Usually, a part is washed for this purpose, grinding is performed and wiped with alcohol, acetone. Rust removal is also an indispensable process for which a grinder can be used. If the gas tank is being repaired, all its contents are drained, degreasing the damage site with white spirit.

Further, the procedure is as follows:

• Stir the weld. If it is in the form of plasticine, cut off the desired size piece strictly perpendicularly, carefully knead the components. In some formulations, the ingredients themselves are mixed as they pass through the dispenser.
• The finished composition is quickly distributed over the surface of the defect or the connected parts. If there is a large hole, it is recommended to apply a metal patch.
• Press the parts against each other, or with a gloved hand, press the formed epoxy patch well. It is necessary to clarify in advance how much this composition dries, and work as quickly as possible.
• Some manufacturers recommend immediately, as the material began to dry, process it with sandpaper to give smoothness. Others advise waiting for the glue to solidify completely - from 1-2 hours to a day. It is better not to start drilling, other processing earlier than an hour after applying the composition to the metal.

The main rules of work

Do not mix liquid two-component products directly on the work surface. For this purpose, a separate container will be required, which then will not come into contact with food. In order not to spoil the excess material, you need to immediately cut off a piece of the required size, and tightly close the residue and put it in a cool room. To achieve excellent adhesion of welding to the surface, quality preparation and, especially, degreasing of the substrate cannot be ignored.

It happens that the old weld must be removed in order to impose a new one. It’s better to clean parts mechanically - with a chisel, file. Next, you need to well treat the surface with acetone or white spirit, then apply a fresh layer of welding.

Precautionary measures

Means for chemical welding can irritate the skin, mucous membranes. If the product gets on the skin, in the eyes, they are immediately thoroughly washed, and in the latter case, you should immediately consult a doctor. Welding should be kept away from children, pets - if accidentally swallowed, there is a high risk of poisoning! It is necessary to work with the material in the presence of ventilation, while always use a respirator to protect against harmful fumes. Almost any metal parts can be joined by cold welding. The seam will be durable and reliable, but only - subject to the instructions for the tool!