Cleaning of machinery parts and equipment
1. Three kinds of cleaning fluid
(1) Organic solvent. Common ones include kerosene, light diesel, gasoline, acetone, alcohol and trichloroethylene. With this way of dissolving oil, can dissolve all kinds of grease. The advantages are no heating, easy to use, no damage to metal, good cleaning effect. The disadvantage is that most of them are flammable, high cost, suitable for precision parts and should not be cleaned with hot alkali solution parts, such as plastic, nylon, cowhide, felt parts, etc. However, it should be noted that rubber parts can not be cleaned with organic solvents.
(2) alkaline solution. Alkaline solution is an aqueous solution of alkali or alkaline salt. It uses emulsifier to emulsify unsaponifiable oil to remove oil. It is one of the most widely used cleaning solution for decontamination.
Emulsification is the formation of tiny fine particles in one liquid that are evenly distributed in another liquid. The emulsifier is added to the alkali solution to form emulsion, which can reduce the surface tension and adhesion of the oil film, so that the oil film will be broken into tiny oil drops and will not return to the metal surface to remove the oil. Commonly used emulsifiers are soap, sodium silicate (sodium silicate), bone glue, gum, triethanolamine, synthetic detergent and so on. It should be noted that different cleaning fluids should be used to clean parts with different materials. Alkaline solution corrodes metals to different degrees, especially aluminum. Table 1 and Table 2 list the formulas of cleaning fluids for steel parts and aluminum parts respectively for your reference.
When cleaning with alkaline solution, it is generally necessary to heat the solution to 80~90℃. After oil removal, rinse with hot water to remove the residual lye on the surface and prevent the parts from corrosion.
(3) Chemical cleaning solution. Is a chemical synthesis of water based metal cleaning agent configuration of aqueous solution, metal cleaning agent is based on surfactants, has a strong decontamination ability. In addition, there are some auxiliary agents in the cleaning agent, can improve or increase the corrosion prevention, rust prevention, carbon and other comprehensive performance of the metal cleaning agent.
The principle is that the cleaning liquid composed of cleaning agent first wets the surface of the parts, and then infiltrates the interface between the dirt and the parts, so that the dirt falls off from the surface of the parts, disperses, or dissolves in the cleaning liquid, or forms emulsion and suspension on the surface of the parts, so as to achieve the purpose of cleaning the parts.
Common configuration of chemical cleaning liquid cleaning agents are lcx-52 water-based metal cleaning agent, cw metal cleaning agent, jsh efficient metal cleaning agent, d-3 metal cleaning agent, dj-04 metal cleaning agent, nj-841 cleaning agent, 817-c oil cleaning agent, cjc-8 liquid metal cleaning agent.
The preparation method, concentration, cleaning temperature and heating measures of the above cleaning agents shall be strictly in accordance with the requirements of the instructions. When cleaning by hand, the temperature should be strictly controlled. Brush and cloth can be used for cleaning. If there is serious oil or carbon accumulation, the wire brush can be used to wash. Before cleaning should be soaked for a certain amount of time to meet the needs of wetting and penetration. Cleaning can be divided into rough cleaning and fine cleaning, cleaning liquid after cleaning if the oil is not serious can be skimmed off the upper floating oil, again used.
2. Five cleaning methods
(1) Scrub. Place the parts in a container of diesel, kerosene or other cleaning solution and scrub with cotton yarn or brush with a brush. This method is easy to operate, simple equipment, but low efficiency, suitable for a single small batch of small parts. Under normal circumstances, gasoline should not be used, because it has fat solubility, will damage people’s health and easy to cause fire.
(2) Boil and wash. Put the configured solution and the parts to be cleaned together into a cleaning pool with appropriate size made of steel plate welding, heat it to 80~90℃ in the furnace under the pool, and boil it for 3~5min.
(3) Spray wash. Spray the cleaning solution with certain pressure and temperature onto the surface of the part to remove oil. This method has good cleaning effect and high production efficiency, but the equipment is complex, suitable for cleaning parts with less complex shape and serious grease on the surface.
(4) Vibration cleaning. The parts to be cleaned are placed in the cleaning basket or cleaning rack of the vibration cleaning machine, and immersed in the cleaning liquid. The vibration generated by the cleaning machine simulates the manual drift rinsing action and the chemical action of the cleaning liquid to remove the oil pollution.
(5) Ultrasonic cleaning. The chemical action of the cleaning solution and the ultrasonic oscillation introduced into the cleaning solution are used to remove the oil.
Precautions: Cleaning methods should be selected reasonably according to the causes and characteristics of oil pollution, so as to ensure the normal use of parts, avoid corrosion or damage to parts caused by cleaning, and prevent environmental pollution and subsequent contamination of parts.
The first type of mechanical parts is mainly used for precision machinery, which has high requirements on the stability of the fit. It requires that the wear limit of the parts does not exceed 10% of the dimensional tolerance value of the parts in the process of use or after multiple assembly. This is mainly used in the surface of precision instruments, meters, precision measuring tools, and the friction surface of very important parts. Such as the inner surface of the cylinder, the spindle neck of the precision machine tool, the spindle neck of the jig boring machine, etc.
The second type is mainly used for ordinary precision machinery, which has higher requirements on the stability of the fit, requires that the wear limit of the parts does not exceed 25% of the tolerance value of the size of the parts, and requires a good close contact surface, which is mainly used in such as machine tools, tools, and the surface of the rolling bearing match, cone pin holes, There are relatively high speed contact surfaces such as sliding bearing matching surface, gear teeth working face, etc.
The third type is mainly used for general machinery, which requires that the wear limit of mechanical parts does not exceed 50% of the dimensional tolerance value, the contact surface of parts without relative motion, such as box cover and sleeve, and the working surface of keys and keyways that are required to be tight. Contact surface with low relative motion speed, such as bracket hole, bushing, working surface of wheel shaft hole, reducer and so on.