Heat-resistant glue for metal: pros and cons
Many prefer heat-resistant glue when working with metal. Its main feature is the ability to withstand high-temperature exposure, as well as its composition is characterized by strength and high adhesion.
Glue on metal is intended for point pasting of metal products. In addition to increased strength, it must have high adhesion and heat resistance. As a rule, such a composition for domestic use withstands heating temperatures up to + 300 ºС, special - a higher temperature effect. Finally, such glue should not cause the development of corrosion, on the contrary, the qualitative composition provides anti-corrosion protection of surfaces. Heat-resistant glue on metal allows fixing not only metal elements, but also metal with stone, brick, ceramics, glass. The composition was widely used when facing and repairing stoves and fireplaces, underfloor heating systems, as well as performing minor household repairs. The main advantage of such products is their ability to replace welding, providing a virtually similar connection in terms of strength.
Using heat-resistant glue is much easier and less expensive, does not require the use of special equipment in contrast to the welding method. Despite the relatively high strength, in relation to this indicator, the glued surfaces are still inferior to the welded ones. The glue may have a semi-liquid consistency or be represented by a plasticine mass, which is heated before application. The peculiarity of liquid hot melts and pastes of similar action is that the final curing of the adhesive surface occurs only during short-term heating. The composition of the classic product for stoves and fireplaces is represented by cement, sand and plasticizers. For bonding parts are usually used compositions based on epoxy resin. Adding synthetic components allows you to vary the characteristics of the adhesive, making these or other properties more pronounced.
Advantages and disadvantages
Among the obvious advantages of glue on metal It is worth highlighting the following:
- increased strength, resistance to vibration;
- weather resistance;
- good adhesion performance, including when gluing differently textured surfaces;
- the ability to withstand high-temperature exposure - for some types of work above + 1000ºС;
- ease of use, the ability to opt out of welding;
- the ability to glue metal not only metal, but also ceramic, glass and other elements;
- high rates of wear resistance and durability, which makes the composition universal;
- environmental friendliness - suitable for interior work in residential premises;
- anti-corrosion protection.
Among the drawbacks, it is worth noting that in terms of the quality of fixing, the adhesive is still inferior to the fixing that cold welding gives. If a part is subjected to active dynamic loads, then gluing is only a temporary measure. In the future, it is necessary to provide better repair or replacement of damaged parts. Many thermal composites are not very easy to use, because for the final polymerization of the adhesive, the parts to be glued need to be heated at rather high temperatures, which requires the use of special heating cabinets, since other heating methods usually lead to deformation of the parts.
Today, there are several of the most well-known varieties of hot melt on metal.
- Hot-melt adhesive K-300-61 It is a three-component refractory composition based on resins, hardener and filler. It is classified as special. Before applying, it requires not only cleaning and drying the working surface, but also its heating to + 50ºС.
- Sun 10-T - This is another kind of special glue that can withstand heating to + 200ºС for 200 hours. Let's admit short-term (no more than 5 hours) heating of glued surfaces up to + 300ºС. The process of using heat-resistant glue involves applying it to the working base, then it must be left in this form for one hour, since the details are not fixed. After the specified time, the bases are connected and placed in a thermal cabinet for 2 hours at a temperature of + 180ºС.
- VK 20 - it is a polyurethane adhesive, which is not heat-resistant, but due to the catalysts contained in it, it is able to withstand short-term heating up to + 1000ºС. It is widely used in the home, as it does not require heating the surfaces when gluing. Although heating to +80 degrees will significantly speed up the drying time.
- Maple 812. This structure is positioned as glue for household, and also semi-professional use. It connects well heterogeneous materials, one of which is metal. It is a paste, which after hardening is characterized by increased rigidity. In this regard, the adhesive is applied only on surfaces that are not subject to vibration.
Buyers also get high appreciation of UHU heat-resistant household compounds. To work with metal, you should look for a product with the appropriate litter Metall. Typically, such a composition is produced in small tubes, has a democratic cost.
How to choose?
For domestic use (gluing lightly loaded elements that are not used in harsh environments) there are usually quite versatile heat-resistant adhesives that allow small-term repairs. At the same time, specialized analogues demonstrate the best technical characteristics in certain conditions.
Criteria for selecting glue should be the following:
- the maximum allowable temperature at which the glued part can be operated;
- time and conditions for drying - it is especially important to find out if high-temperature heating of parts is required for adhesive polymerization;
- methods of application - is it enough to apply glue pointwise or does it cover the entire surface, and sometimes the surfaces of both parts completely, since the consumption of the composition and its quantity depends on it;
- release form, consistency - these concepts are interconnected, since the liquid composition is produced in tubes, more dense, and the plastic-like version comes in the form of sticks; the latter requires mixing in a separate container, but you can take any, even a very small amount of glue, without worrying that the rest will dry out quickly;
- moisture resistance, weather resistance - these indicators are important when buying adhesive for exterior work, and for fixing parts in contact with water, you should definitely get a waterproof composition;
- for what materials is glue.
Important: the inscription "cold welding" does not mean that the composition is a priori suitable for metal. By the same principle it is possible to fix wooden, glass, textile and ceramic surfaces. Not mistaking the choice will help the study of information about what surfaces can glue this composition.
For rubber, you should select a special glue that does not destroy its surface. Naturally, for its polymerization does not need heating.
Each type of glue differs in features of drawing. Usually they are stated in the instructions attached to the product, or are indicated on the packaging.
In general, the gluing process involves several steps.
- Preparation of working grounds for cleaning dust and dirt from the surface, traces of oils, solvents. Rusty metal must be cleaned until a characteristic metallic luster appears. Too porous surfaces can be pre-primed with a suitable composition and wait for them to dry completely. Too smooth surfaces are recommended to slightly sand, thereby increasing the roughness of the material and improving its adhesion.
- Apply glue to clean, dry surfaces. The composition is usually applied to both parts in a thin layer (about 1–2 mm). After which it must be left for 1 hour, although the time may vary. Some manufacturers say that details should be fixed.
- After the specified time for the final curing of the adhesive, it is visited in heating cabinets or subjected to heating in another way. The minimum heating temperature is usually from + 50ºС, the maximum temperature for professional adhesives can reach about + 200ºС. Heating time is also individual for each product.
About the very strong glue Hosch, see the following video.