Welding is a traditional method of bonding metal elements. However, today there is a decent alternative characterized by ease of use and affordability. We are talking about a plastic mass for fixing metal surfaces - cold welding.
Features of the
This composition is a plastic glue that resembles plasticine in consistency. This feature, as well as improved adhesion rates, are due to the composition of the mass - it is based on epoxy resin.
Typically, the epoxy is located in the center of the cylinder, the outside of which is the hardeners. The high strength of the seams is achieved by mixing the resin with metal dust. To provide the composition with certain technical properties, various components are added to it, the most common of which is sulfur. Manufacturing processes and material composition comply with GOST 2601-74. When using this composition, SNiP 3-42-80 should be followed.
Despite the fact that welding provides high strength and reliable adhesion of parts, sooner or later the broken elements must be replaced or repaired by a more "serious" method. This composition is very much in demand for eliminating leaks in plumbing devices (sealing cracks in pipes, restoring threaded connections, etc.), minor repairs, domestic use.
The glue demonstrates its qualities in the best way when gluing parts that are not subject to heavy loads.
The ease of use of this composition lies in the fact that it is suitable for application to both hollow and filled surfaces, as well as parts subjected to low pressure. There is no need to dismantle the parts, gluing can be done even in hard-to-reach places. This method does not involve heating, which means that deformation of the metal is excluded, as well as a negative effect on neighboring heat-sensitive elements.
The work itself does not require professional skills, spending on purchasing or renting equipment. The seizure of surfaces begins a few minutes after application, and the part being repaired can be used in a day. Due to the variety of compositions, it is possible to choose an adhesive for a specific part, including those used in extreme conditions. So, there are such types of cold welding that tolerate high-temperature exposure up to 1000 ° C.
Despite the fact that in its strength the seam formed by cold welding is inferior to the joint obtained by the conventional welding method, it is quite strong and one-piece. It is recommended to use the composition to eliminate small-sized damages, seal fistulas. Cold welding is compatible with all types of metals, especially those sensitive to heat. It also enables the bonding of dissimilar metal surfaces. The formed seam looks neat, can be sanded, painted.
This type of connection is based on the principle of pressure, however, the seam is formed due to the plasticity of the adhesive and the ability of its particles to attract material molecules. In other words, plastic deformation occurs, as a result of which the oxide layer on the repaired surfaces is destroyed, and the distance between them becomes similar to the distance in the crystal lattice.At the same time, the energy level of atoms rises, they become able to form chemical bonds.
Depending on the characteristics of the composition, cold welding can be one-component and two-component. The first one is not suitable for long-term storage, open glue must be used at one time.
If we talk about the scope of application, the following types of cold welding are distinguished
- Universal. Due to the peculiarities of the composition, it is suitable for gluing not only metal, but also plastic, rubber surfaces, including with each other.
- Automotive. Designed to eliminate cracks and minor damage on metal surfaces of the vehicle, such as tanks, radiators, connecting pipes, etc.
- Provides improved adhesion performance… This property is achieved by adding steel, aluminum or cast iron chips to the resin. Suitable for parts subjected to increased loads and pressure, increases the strength and thermal stability of the weld formed.
- High temperature. This is a high-viscosity heat-resistant metallosilicate welding, which can be operated at temperatures up to + 1500 ° C. The lower temperature threshold is usually -60 ° C.
- Waterproof. 2-component welding, which does not lose its performance not only in a humid environment, but also in direct contact with water. It is mainly used for the repair of plumbing equipment.
Based on the consistency, liquid and plastic-like compositions are isolated. Liquid welding is always a two-component compound consisting of epoxy resin and hardener. It is produced in syringes, mixing of the components takes place there automatically. However, experts recommend that you still mix the components in a separate bowl immediately before use.
The plastic-like mass is more viscous, it is a one-component or two-component bar. Before use, it is kneaded until a homogeneous elastic mass is obtained.
The adhesive can also be differentiated into the following groups:
- point (glue for aluminum and copper coatings, used to eliminate small gaps, weld small parts to larger surfaces);
- suture (designed to eliminate integrity violations in thin-walled sealed vessels and tanks, used in conjunction with contour punches);
- tee (scope of application - fixing brass pins with transformer windings outlets made of aluminum, tee and angle bus ducts for electric locomotives);
- butt (suitable for gluing wires, closing ends, forming rings);
- shear welding (used in the repair of water and heating pipes, on the railway - to connect adapters in power lines).
How to use it correctly?
The quality of adhesion of the glue largely depends on how carefully the working base is prepared. It needs to be cleaned of traces of rust, degreased. For this, special solvents and sandpaper are used.
The part covered with rust should be rubbed with sandpaper until a layer of a characteristic metallic shade with traces of scratches appears. Smooth surfaces should also be sanded until scratched. This will improve grip.
The next step is surface drying. You can let the base dry naturally or use a regular hair dryer. Manufacturers note that cold welding can also be applied to wet parts, but practice shows that the quality of such joints is lower. After drying, the surfaces should be degreased again using, for example, acetone.
After the surface is ready for gluing, it is necessary to cut off the required amount of glue from the cylinder. It should be cut only in the transverse direction so that the resulting "round" contains both the epoxy core and the hardener that surrounds it. If a liquid mixture is used, then it is squeezed out of the syringe tube directly onto the surface of the part (as the instructions say) or pre-mixed in the dishes (as the professionals recommend).
The cut piece must be warmed and homogeneous by rubbing in your hands. The longer you do this, the softer and more plastic the composition will become.
If it sticks too much to your hands, you can periodically moisten them with cold water. Work should be carried out with gloves, and the dishes in which the mixture was kneaded or was located cannot be used in the kitchen in the future.
When you feel that the mass adheres well and spreads easily, you should immediately apply it to the surface to be repaired. If the gap formed is small, then it is desirable that some of the glue penetrates inside it. For larger gaps, it is better to use "patches" that are fixed by cold welding.
It is advisable to make the welding layer no more than 5 mm. If necessary, you can apply several layers, waiting for the previous one to dry completely before applying the next one. Most formulations begin to solidify within a few minutes after adhesion to the surface. The final solidification occurs after a day. 24 hours after applying the glue, you can proceed to further processing of the repaired surface.
The leading positions in the market are occupied by imported products. Domestic counterparts, according to user reviews, do not demonstrate the same high quality and strength of the seam.
The most durable welding, in the opinion of professionals, as well as on the basis of expert data, is produced under the brands Hi-Gear, Abro, Poxipol
- The variant from the first brand is a universal compound suitable for working on metal, as well as stone and plastic surfaces. Demonstrates heat resistance and chemical inertness.
- Abro is a two-component welding that also offers versatility. Withstands heating up to 260 ° C, suitable for use in chemically aggressive environments.
- Domestic analogues close to them in quality are Polymet and Almaz.
- For water supply and heating pipes, it is better to use Mastix products, but only on condition that the coolant in these systems has a temperature of no more than 120 ° C. This makes the compound an excellent choice for home welding, but does not allow it to be used for repairing production systems with a higher heating temperature.
- For heat-resistant systems, it is better to choose Kerry "Thermo" glue, which is characterized by high viscosity and the ability to withstand heating up to + 900 ° C. This compound has proven itself well when working with cast iron, steel and titanium bases, and is widely used in car repairs.
- Good quality is demonstrated by Henkel's product "Moment SuperEpoxy" for universal use, which can withstand temperatures up to 140 ° C. The composition of Adefal Trading S. A. Poxipol demonstrates similar properties, but the heating temperature during its use can reach only 120 ° C.
Tips & Tricks
- When choosing cold welding, it is necessary to take into account the scope of its application. It is better if the metal used in the glue is similar in composition to the surface to be repaired. If it is impossible to find such a composition, you should choose welding with a metal core, the strength indicators of which are not inferior to those of the surface metal.
- It is important to pay attention to the temperature range of the glue operation. Despite the fact that all its varieties can withstand an increase in temperatures (on average up to 200-230 ° C), specialized compositions should be chosen for surfaces exposed to significant heating or the action of an open flame.
- If you need a quick repair, it is advisable to use 2 types of welding. First, a layer is applied that is characterized by an accelerated solidification time (about an hour). This will allow you to quickly eliminate the accident. However, this layer cannot be called durable, therefore another welding layer is applied on top of it with a standard hardening time (dries 24 hours).
- Removing frozen cold welds is not easy. For this, special solvents are used, if they are not available, acetone. They need to thoroughly moisten the glue and try to pick it up by the edge of the base. If this can be done, the weld is literally ripped off the surface.
This method by itself can damage the surface, and if acetone is applied on wood, glass or ceramic substrates, it can cause darkening. In this regard, the composition should be applied carefully and carefully, without scattering the prepared and mashed glue over the surfaces adjacent to the workers.
For how to use cold welding, see the next video.