As the remanufacturing plant has been paid more and more attention, people have also begun to explore various fields of remanufacturing, and have achieved certain research results in the logistics, management, and technology of remanufacturing. In the remanufacturing process, it is an important part of cleaning the parts to ensure the quality of remanufacturing. The cleaning method and cleaning quality are important for the accuracy of parts identification, ensuring remanufacturing quality, reducing remanufacturing costs, and improving the life of remanufactured products. can have an important impact.
1. The position and importance of cleaning in the remanufacturing process
Cleaning the surface of product parts is an important process in the process of part remanufacturing. The premise of the division to detect the dimensional accuracy, geometric shape accuracy, roughness, surface performance, corrosion wear and adhesion of the part surface is the basis for the division to remanufacture the parts. . The quality of part surface cleaning directly affects part surface analysis, testing, remanufacturing processing, assembly quality, and then affects the quality of remanufactured products.
Cleaning is to apply the cleaning liquid to the surface of the workpiece by means of cleaning equipment, and use mechanical, physical, chemical or electrochemical methods to remove grease, corrosion, mud, scale, carbon deposits and other dirt attached to the surface of the equipment and its parts, and make it The process of achieving the required cleanliness on the surface of the workpiece. The disassembled parts of waste products are cleaned according to the shape, material, category, damage, etc., and the corresponding methods are used to ensure the quality of the reuse or remanufacturing of the parts. Product cleanliness is one of the main quality indicators of remanufactured products. Poor cleanliness will not only affect the remanufacturing process of products, but also often cause the performance of products to decline, prone to excessive wear, decreased precision, and shortened service life. Quality of products. Good cleanliness can also improve consumer confidence in the quality of remanufactured products.
The remanufacturing process includes recycling of waste products, appearance cleaning of products before dismantling, dismantling, rough testing of parts, cleaning of parts, accurate detection of parts after cleaning, remanufacturing, assembly of remanufactured products, etc. process. Cleaning includes two parts: the overall cleaning of the appearance of waste products and the cleaning of parts. The former is mainly to remove dust and other dirt on the appearance of the product, and the latter is mainly to remove oil, scale, rust, carbon deposits and other dirt on the surface of parts. Oil and gas layers on the surface, etc., check the wear of the parts, surface microcracks or other failures to determine whether the parts can be used or need to be remanufactured. The remanufacturing cleaning is different from the cleaning of the maintenance process. The main maintenance engineer cleans the faulty parts and related parts before maintenance, while remanufacturing requires all the waste product parts to be cleaned completely, so that the quality of the remanufactured parts can reach the level of new products. standard. Therefore, cleaning activities play an important role in the remanufacturing process, and the heavy workload directly affects the cost of remanufactured products, so it needs to be given great attention.
2. Cleaning technology and its development in remanufacturing
2.1 Cleaning technology for remanufacturing
Like the dismantling process, it is impossible for the cleaning process to directly learn from the common manufacturing process, which requires the research of new technical methods and the development of new remanufacturing cleaning equipment in manufacturers and remanufacturing equipment suppliers. According to the cleaning location, purpose, complexity of materials, etc., the cleaning method used in the cleaning process. The cleaning methods usually used are gasoline cleaning, hot water spray cleaning or steam cleaning, chemical cleaning agent cleaning chemical purification bath, scrubbing or steel brush scrubbing, high pressure or normal pressure spray cleaning, sandblasting, electrolytic cleaning, gas phase cleaning, ultrasonic cleaning and Multi-step cleaning and other methods.
In order to complete each cleaning process, a whole set of various special cleaning equipment can be used, including: spray cleaning machine, spray gun machine, comprehensive cleaning machine, special cleaning machine, etc. The selection of equipment needs to be determined according to the remanufacturing standards, requirements, environmental protection, cost and remanufacturing site.
2.2 Development trend of cleaning technology
The cleaning step is a major source of contamination during remanufacturing. Moreover, the harmful substances produced by the cleaning process often endanger the environment. Moreover, the cost of harmless disposal of harmful substances is also surprisingly high. Therefore, in the remanufacturing cleaning step, it is necessary to reduce the harm of the cleaning solution to the environment and adopt green cleaning technology. Remanufacturers have carried out a lot of research and extensive application of newer and more effective cleaning technologies, and the cleaning process has become more and more environmentally friendly. While improving the cleaning efficiency, reduce the discharge of harmful substances, reduce the impact on the ecological environment, increase the environmental protection of the cleaning process, and increase the quality of parts.
3 .Cleaning activities at each stage of remanufacturing
Cleaning in the remanufacturing process mainly includes external cleaning of waste products before dismantling and cleaning of parts after dismantling.
3.1 Cleaning before disassembly
The cleaning before dismantling mainly refers to the external cleaning of the recycled waste products before dismantling. Its main purpose is to remove a large amount of dust, oil, sediment and other dirt accumulated on the outside of the waste products, so as to facilitate dismantling and avoid dust and oil. Wait for the stolen goods to be brought into the factory process. External cleaning generally uses tap water or high-pressure water flushing. For high-density and thick-layer dirt, add an appropriate amount of chemical cleaning agent to the water and increase the spray pressure and water temperature.
Commonly used external cleaning equipment mainly includes single-gun jet cleaning machines and multi-nozzle jet cleaning machines. The former mainly relies on the scouring action of the high-pressure contact jet or the soda jet or the chemical action of the jet and the cleaning agent to remove the dirt. The latter has two types, the door frame movable type and the tunnel fixed type. The installation position and quantity of the nozzles vary according to the purpose of the equipment.
3.2 Cleaning after disassembly
The cleaning of parts after disassembly mainly includes removing oil, rust, scale, carbon deposits, paint, etc.
3.2.1 Degreasing
All parts in contact with various oils must be cleaned of oil after disassembly, that is, degreasing. It can be divided into two categories: saponifiable oil, that is, oil that can react with alkali to form soap, such as animal oil and vegetable oil, that is, high molecular organic acid salt; unsaponifiable oil, which cannot act with strong alkali, such as Various mineral oils, lubricating oils, petroleum jelly and paraffin, etc. These oils are insoluble in water but soluble in organic solvents. The removal of these oils is mainly done by chemical and electrochemical methods. Commonly used cleaning solutions are: organic solvents, alkaline solutions and chemical cleaning solutions. Cleaning methods include manual and mechanical methods, including scrubbing, boiling, spraying, vibration cleaning, ultrasonic cleaning, etc.
3.2.2 Descaling
After the cooling system of mechanical products has used hard water or water with a lot of impurities for a long time, a layer of silicon dioxide is deposited on the inner wall of the cooler and the pipe. Scale reduces the cross-section of the water pipe and reduces the thermal conductivity, seriously affecting the cooling effect and affecting the normal operation of the cooling system. Therefore, removal must be given during remanufacturing. Scale removal methods generally use chemical removal methods, including phosphate removal methods, alkaline solution removal methods, pickling removal methods, etc. For scale on the surface of aluminum alloy parts, 5% nitric acid solution or 10-15% acetic acid solution can be used. The chemical cleaning fluid for removing scale should be selected according to the scale components and parts materials.
3.2.3 Removing paint
The original protective paint layer on the surface of the disassembled parts also needs to be completely removed according to the degree of damage and the requirements of the protective coating. Rinse well after removal and prepare for repainting. The method of removing the paint is generally to use a prepared organic solvent, alkaline solution, etc. as a paint remover, first brush on the paint surface of the part, dissolve and soften it, and then use hand tools to remove the paint layer.
3.2.4 Rust removal
Rust is the oxides formed by the contact of the metal surface with oxygen, water molecules and acid substances in the air, such as iron oxide, ferric oxide, ferric oxide, etc., which are usually called rust; the main methods of rust removal are mechanical method, chemical pickling and electrochemical etching. Mechanical rust removal mainly uses mechanical friction, cutting and other actions to remove the rust layer on the surface of parts. The commonly used methods are brushing, grinding, polishing, sandblasting and so on. The chemical method mainly uses the acid to dissolve the metal and the hydrogen generated in the chemical reaction to connect and unload the rust layer to dissolve and peel off the rust products on the metal surface. Commonly used acids include hydrochloric acid, sulfuric acid, phosphoric acid, etc. . The electrochemical acid etching method mainly uses the chemical reaction of the parts in the electrolyte to achieve the purpose of rust removal, including using the rust-removed parts as anodes and using the rust-removed parts as cathodes.
3.2.5 Cleaning carbon deposits
Carbon deposition is a complex mixture of colloids, asphaltenes, lubricating oils and carbons formed due to the incomplete combustion of fuel and lubricating oil during the combustion process and under the action of high temperature. For example, most of the carbon deposits in the engine are accumulated on the valves, pistons, cylinder heads, etc. These carbon deposits will affect the cooling effect of certain parts of the engine, deteriorate the heat transfer conditions, affect its combustion, and even cause the parts to overheat and form cracks. Therefore, during the remanufacturing process of this part, the carbon deposit on the surface must be cleanly removed. The composition of carbon deposits has a great relationship with the structure of the engine, the location of parts, the types of fuel and lubricating oil, working conditions and working hours. The commonly used mechanical methods, chemical methods and electrolytic methods can clear carbon deposits. The mechanical method refers to the use of wire brushes and scrapers to remove carbon deposits. The method is simple, but the efficiency is low, it is not easy to clean, and it will damage the surface. The removal of carbon deposits by using compressed air jet nuclear chip method can significantly improve the efficiency. The chemical method refers to immersing the parts in caustic soda, sodium carbonate and other cleaning solutions at a temperature of 80~95°C to dissolve or emulsify the oil and soften the carbon deposits, then use a brush to remove the carbon deposits and clean them. The electrochemical method uses alkaline solution as the electrolyte, and the workpiece is connected to the cathode to remove carbon deposits under the joint stripping action of chemical reaction and hydrogen. This method is efficient, but it is necessary to master the specifications of carbon deposition.
4 Conclusion
1) Remanufacturing cleaning is an important part of the remanufacturing process, which directly affects the quality of remanufactured products and the cost of remanufacturing, and must be given sufficient attention
2) Remanufacturing cleaning technology will develop in the direction of cleaning, environmental protection and high efficiency, and the cleaning method of chemical solvents will gradually develop in the direction of water-based mechanical cleaning to reduce environmental pollution in the process.
3) Cleaning in the remanufacturing process can be divided into cleaning before dismantling and cleaning after dismantling, the latter including cleaning of oil, rust, scale, carbon deposits, paint, etc.
Choosing the right cleaning method and cleaning equipment can achieve twice the result with half the effort, and also provide a stable foundation for the development of the remanufacturing industry. As a professional manufacturer of cleaning equipment, Tense can provide professional cleaning solutions and services.