What factors determine the degreasing quality of bearing anti-rust oil?
February 04, 2023
The degreasing quality mainly depends on four factors: degreasing temperature, degreasing time, mechanical action and degreasing agent.
1. Degreasing temperature Generally speaking, the higher the temperature, the more thorough the degreasing. This is due to three reasons: First, temperature changes the physical properties of oil stains, such as anti-rust grease with high drop point, vaseline, solid paraffin, etc., which is difficult to clean even with high concentration of alkaline solution at low temperature. However, when the temperature of oil stains is increased, their viscosity will be reduced, and even droplets will be formed to facilitate removal. Second, promote the chemical reaction. Generally speaking, the chemical reaction speed will be doubled for every 10 ℃ rise in temperature. Third, accelerate the movement of surfactant molecules, thus promoting the functions of infiltration, emulsification and dispersion. With the increase of temperature, the solubility of the solution to the dirt also increases. However, the higher the temperature is, the better is not always the case. All kinds of degreasing agents have their own suitable temperature range. In degreasing solutions using some kinds of surfactants, the higher the temperature will make the surfactant precipitate and gather like oil beads attached to the surface, causing uneven phosphorization film. 2. Degreasing time During the degreasing operation, it is necessary to ensure that there is sufficient degreasing time. The pressure jet degreasing time is generally 1.5~3 minutes, and the immersion degreasing time is 3~5 minutes (depending on the type and amount of oil). Increase the degreasing time, that is, extend the contact time between degreasing solution and oil stain, so as to improve the degreasing effect. The more oil, the longer the degreasing time. In the assembly line operation, it is often not allowed to use too long time. Therefore, spray degrease for 1 minute first, and then dip degrease for 3 minutes. 3. Mechanical action During degreasing, it is very effective to use mechanical action such as pressure spraying or stirring, because the fresh degreasing solution is forced to have good contact with the surface of the part during spraying, and the content of the whole degreasing solution is uniform, which is conducive to improving the degreasing effect; During spraying, the degreaser is forced to penetrate and destroy the oil film by mechanical force, thus effectively forcing the oil stain off the surface of the part; During spraying, the oil stains separated from the parts will be emulsified and dispersed in the degreasing solution to prevent the oil stains from being adsorbed on the cleaned part surface again. In medium and low temperature degreasing, the mechanical effect is particularly important. Generally speaking, the speed of pressure jet degreasing is more than one time faster than that of impregnation. The injection pressure is usually (0.1~0.2) Mpa (the degreasing agent used for pressure injection must be low foam to avoid excessive foam affecting normal operation and the loss of degreasing liquid), and the degreasing by impregnation cannot be considered as static impregnation. A circulating pump must be equipped to keep the solution stirring, and the circulating amount per hour is about 5 times of the tank liquid volume. 4. Effect of degreasing agent on degreasing effect The composition and application method of degreasing agent have great influence on degreasing effect. For example, the degreasing effect of alkaline solution containing surfactant is better than that of alkaline solution alone. For solid or semi-solid grease with high drop point, solvent cleaning is more effective than other degreasing methods. In order to improve the emulsification and dispersion ability of oil pollution, it is effective to properly increase the content of surfactant in degreasing agent. Different types of surfactant and different alkalis make certain difference in degreasing effect. Good degreasing agent is determined by repeated screening of its component matching ratio through a large number of tests. For alkaline degreasing agent containing surfactant, the most effective washing effect is at the upper limit of the critical micelle concentration of surfactant. In the process of use, the degreasing agent will be continuously consumed and the concentration will be reduced. Therefore, the degreasing agent must be added regularly to maintain the necessary concentration. The degreasing effect of degreasing agent is not linear with the concentration. Therefore, the method of significantly increasing the concentration should not be adopted in the case of high degreasing quality requirements, but the method of secondary degreasing should be adopted. The two degreasing solutions can be the same, and there is no need to increase the concentration additionally. In practical use, various factors must be considered to control all factors in the best state to achieve satisfactory degreasing effect.
