Metal Degreasing Agent Surface treatment
Degreasing, other than oil. Degreasing is a very important step in pretreatment of metal surfaces. The oil on the metal surface is from the processing of the material, the parts processing and completion of the various links, in the storage and transportation process to prevent rust use the products such as anti-rust oil.
In general, metal materials and parts in further to do surface treatment (such as plating, coating, anodic oxidation, passivation, etc.) before must put the oil on the surface of the clean, otherwise it will affect the rust removal, scale removal, which affect the quality of the surface electroplating, coating layer. Since the source of oil pollution is wide and varied, the degree of pollution varies greatly, so the oil problem is very complicated. In addition also takes a lot of oil removal of objects, all kinds of metal material, size, shape complexity of the workpiece, also has the whole machinery and equipment (such as cleaning machine, food equipment cleaning and disinfection), etc., it is enough to illustrate skim oil removal work is complex, wide influence. Therefore, many degreasing processes must require strict cleaning and even national or international standards.
1. Degreasing influence factors
The quality of the degreasing effect depends on the degreasing temperature, degreasing time, mechanical function and degreasing agent.
1. Degreasing temperature
Generally speaking, the higher the temperature, the more thorough degreasing. There are three reasons:
(1) temperature causes the physical properties of the oil to change, such as anti-rust oil, vaseline, solid paraffin, etc., which are high in the drop point, which can be difficult to clean even with high concentration of lye at lower temperatures. However, when the temperature of the oil is increased, their viscosity is reduced, and even droplets are formed to help remove them.
(2) to promote the chemical reaction, generally speaking, the chemical reaction rate doubled every 10 degrees.
(3) accelerate the movement of surfactant molecules to promote infiltration, emulsification and dispersion. As the temperature rises, the solubility of the solution increases. However, not all situations are the higher the temperature, the better, all kinds of degreasing agent has its suitable temperature range and certain kinds of surfactants used in the degreasing fluid, high temperature can make the surface active agent precipitation gathered as oil bead adhesion on the surface, causing uneven skin membrane into. 2. Degreasing time
In the degreasing operation, it is necessary to ensure that there is sufficient degreasing time. The high pressure spray degreasing time is usually 1.5-3 minutes, and the impregnation is 3-5 minutes (depending on the type and amount of oil pollution). Increase the degreasing time, which is to extend the contact time of the degreasing agent and the oil, thereby increasing the degreasing effect. The more oil, the longer the skim time. In automatic production lines, it is often not allowed to take too long, so spray (drizzle) is generally used for 1 minute, and then soak in an impregnation for 3 minutes.
3. Mechanical action
In degreasing, mechanical action such as pressure jet or agitation is very effective. Because of the injection, the fresh degreasing agent has good contact with the surface of the workpiece, and the whole degreasing agent is uniform, which is beneficial to improve the degreasing effect. The mechanical force is used to induce the degreasing agent to penetrate and destroy the oil film, thus effectively forcing the oil to disengage from the surface of the parts. When spraying, the oil is emulsified and dispersed in a nonfat solution, preventing oil from being adsorbed to the surface of the clean parts. Mechanical action is particularly important in low - temperature degreasing.