Can metal repair kits be trusted for repairs?

Reply to 1# ljx20080513: I’m not sure what kind of device it is. Once, the outer ring of the exciter bearing on a 6MW generator became enlarged; I repaired it using a metal repair compound, and it worked fine for several years.

Reply to 2# hcwang12345: The radial bearings of the submersible pump have a fairly large wear gap; I’m concerned that using a repair agent won’t be sufficient to achieve shaft concentricity

Reply to 3# ljx20080513: Using a repair agent to ensure the concentricity of the shaft is a problem related to the repair process; this issue exists whether it involves sleeve installation or spraying. In comparison, using a repair agent, a skilled fitter can achieve this much more easily.

Hehe, it’s okay for now； Poor long-term efficacy

If the strength of the metal repair compound is sufficient, it can be used as well. We use imported repair compounds, but only on smaller shafts; we haven’t dared to use them on larger ones.

I used an imported repair compound to repair the sealing surface of the intake valve seat in the reciprocating compressor, and it has worked fine for three years.

The outer ring of a pump bearing in my unit is too large; can I use metal repair compound? Can it meet the technical requirements? Regarding the issue above, I’d like to share some thoughts: When you say the outer ring of the bearing is too large, do you mean the degree of wear on the inner circular surface of the bearing housing that fits with the outer ring of the bearing? Has it been measured? Industrial pumps and motors operate continuously throughout the year, so it’s not surprising that such situations occur; our factory is no exception. Over the years, we have adopted measures such as filling with patching compounds and electroplating repair, which have yielded good results. Examples of metal repair agents include: in the case of the outer ring of the bearing at the front end of the condensate pump coming loose from its seat hole, Loctite 755 and 680 can be used. Clean the mating surfaces with Loctite 755, apply Loctite 680 to the inner surface of the seat hole after a few minutes, and then coat the outer surface of the bearing with Loctite 680 to create a sealing layer; once this is done, the bearing can be pressed back in place, and there will be no issues with the fit. Another measure is brush plating, which yields even better results. Brush plating is easy to carry out and does not require high costs; thanks to the uniform coating formed along the circumference, the concentricity between the bearing and its housing remains unchanged after repair, and the adhesion strength between the coating and the base material is very high.

It is not recommended to do this, as it does not guarantee quality. For bearings in which the outer ring has moved out of place, we usually turn the outer ring slightly on a lathe, then fabricate a sleeve to fit over it, and finally insert the bearing into this fabricated sleeve

In fact, industrial repair compounds are no longer merely a temporary solution for emergency repairs; their reliability is sometimes even greater than that of traditional methods such as sleeve installation. Industrial repair compounds refer to an industrial technique in which adhesives containing special materials (aggregates) are applied to the surface of parts in order to repair damaged parts or endow the surface with specific properties such as wear resistance, high-temperature resistance, and corrosion resistance. In recent years, industrial repair compounds, both imported and domestically produced, have been widely used in industries such as automobiles, ships, machine tools, and construction machinery. These repair compounds are primarily used for repairing components in mechanical products, such as castings and machined parts. Defects and machining errors during the manufacturing process can lead to the scrapping of parts, while wear and tear on parts can also cause them to fail. Using repair agents can enable these parts to function properly, and they can also be used in the manufacture of machine tool guides. Therefore, the repair agent offers significant economic and social benefits. I. Basic Process Steps 1. Surface Treatment: Industrial repair compounds bond to the substrate primarily through chemical bonds, and the quality of surface treatment largely determines whether the repair can be completed successfully. The surface of the workpiece to be repaired must be free of grease, rust, dust, and moisture; these contaminants can reduce the adhesion of the repair material to that surface, leading to local peeling or cracking of the coating. One of the methods to ensure good bonding strength is to carry out rigorous surface treatment. (1) Cleaning. Carefully remove surface oils using a solvent-based metal cleaner. For components that are heavily contaminated with oil, it is possible to first use a blowtorch or oxy-acetylene flame to heat the surface, thereby enhancing the adhesion strength between the repair material and the substrate. (2) Roughening, polishing. Use tools (angle grinders, sandpaper, steel brushes, files, or sandblasting guns, etc.) to remove loose particles, rust, and surface contaminants from the surface, or use an acidic rust remover for rust removal; afterwards, rinse thoroughly with clean water and dry it. (3) Wash again. Clean the roughened surface again with a solvent-based metal cleaner to ensure it is clean. 2. Preparation of the two-component repair compound: There is a strict ratio required between Component A (the resin) and Component B (the curing agent), as only by adding the exact amount of Component B to Component A can complete curing be achieved, along with optimal mechanical and chemical properties. (1) Accurate proportioning. The ingredients must be weighed strictly according to the mixing ratio specified in the instructions. It is recommended to use a weight ratio, and a balance with an accuracy of 0.1g is the best choice for weighing. (2) Mix. The repair compound consists of Component A and Component B, and the two components should be mixed evenly. The correct mixing method is to use a mixing tool to combine the two components together, then stir and roll them in one direction until the colors are uniform. The stirring speed should not be too fast to avoid the inclusion of air. 3. Coating (1) Processing and shaping method. Apply the mixed repair compound to the surface that has been treated and is to be repaired. The first layer should be thin, and pressure should be applied repeatedly to ensure that the repair material penetrates thoroughly into the metal surface; thereafter, layers can be applied gradually to increase thickness, leaving some excess for further processing. (2) Molding method. The repair layer is formed using high-precision molds without any further processing; for example, by applying a release agent to a mold that has been ground, a highly precise coated surface can be created. First, apply or spray a release agent onto the surface of the mold to form a uniform film ； According to the processing and molding method, the mixed repair material is applied to the surface of the watch to be repaired as well as the inner surface of the mold, and finally the mold is closed and pressed in place. 4. Curing (1) Ordinary metal part repair compound. Cure the repair part for 24 hours at a temperature of 15–40°C and a relative humidity of less than 80%. If the temperature is below 15°C, appropriate heating should be applied to achieve complete curing. After curing at room temperature, heating to 80–100°C and maintaining that temperature for 3 hours can improve the overall performance of the repair layer by 10%–30%. (2) Fast-setting metal part repair compound. Cure the repair part for 12 hours at a temperature of 15–40°C and a relative humidity of less than 80%. After curing at room temperature, heating to 80–100°C and holding it there for 2 hours can improve the overall performance of the repair layer by 10%–30%. 5. Machining (1) The parts after curing can be machined (turning, grinding, drilling, tapping, etc.) to achieve the desired dimensional accuracy. (2) If pores are exposed on the surface after processing, the above basic process steps need to be repeated.

I’m not familiar with the use of repair adhesives; although I’m very interested, I don’t have the means to learn about it*