How is degreasing agent used in metal processing?

Degreasers play a vital role in metal processing. They are mainly used to remove grease, dirt and other impurities on the metal surface to ensure the quality and effect of subsequent processing steps (such as painting, electroplating, welding, etc.). The cleanliness of the metal surface directly affects the performance, appearance and durability of the product, so the selection and use of degreasers are particularly important in the metal processing process.

1. Basic principles and classification of degreasing agents

Degreasers mainly remove grease and dirt from metal surfaces through physical and chemical effects. Its working principle includes processes such as emulsification, dissolution, saponification and dispersion. According to the ingredients and uses, degreasers can be divided into the following categories:

1. Alkaline degreasing agent: It is mainly composed of alkaline substances such as sodium hydroxide and sodium carbonate. It can convert oil into water-soluble soap substances through saponification reaction. It is suitable for removing animal and plant oils and some mineral oils.

2. Acidic degreasing agent: It is mainly composed of acidic substances such as sulfuric acid and hydrochloric acid. It is mainly used to remove oxide layers and rust on the metal surface. It also has a certain removal effect on certain greases.

3. Solvent degreaser: With organic solvents (such as acetone, ethanol, trichloroethylene, etc.) as the main ingredients, it achieves the cleaning effect by dissolving grease. It is suitable for removing heavy oil stains and difficult-to-handle grease.

4. Emulsified degreaser: It disperses grease in water through emulsification to form a stable emulsion, which is easy to rinse. It is suitable for removing a variety of grease.

5. Bio-enzyme degreaser: It uses the catalytic effect of bio-enzymes to decompose grease. It is environmentally friendly and non-corrosive to metal surfaces. It is suitable for occasions with high environmental protection requirements.

2. How to use the degreasing agent

In metal processing, the use of degreasing agents varies depending on the type of workpiece, the type of grease and the processing requirements. The following are several common degreasing methods:

1. Immersion method: Immerse the metal workpiece completely in the degreaser solution to remove grease through chemical reaction or physical action. The immersion time depends on the thickness of the grease and the concentration of the degreaser, usually from a few minutes to tens of minutes. The immersion method is suitable for small workpieces or batch processing.

2. Spraying method: The degreaser solution is sprayed on the metal surface through high-pressure spray equipment, using mechanical force and chemical action to remove grease. The spraying method is suitable for large workpieces or parts with complex surfaces, and can clean the surface quickly and evenly.

3. Ultrasonic cleaning method: Place the metal workpiece in an ultrasonic cleaning tank filled with a degreasing agent solution, and use the cavitation effect of ultrasound to accelerate the removal of grease. Ultrasonic cleaning is suitable for precision parts or occasions with extremely high cleanliness requirements.

4. Steam degreasing method: Heat the degreasing agent to steam state, and use the high temperature and chemical action of steam to remove grease. Steam degreasing method is suitable for removing stubborn grease and difficult-to-handle dirt.

5. Wiping method: Use a cloth or sponge soaked in degreaser to directly wipe the metal surface. It is suitable for local cleaning or small area treatment.

3. Precautions in using degreasing agent

1. Choose the right degreasing agent: Choose the right degreasing agent according to the properties of the metal material, the type of grease and the processing requirements. For example, metals that are sensitive to alkaline substances, such as aluminum alloys, should avoid using strong alkaline degreasing agents.

2. Control the concentration and temperature of the degreaser: The concentration and temperature of the degreaser directly affect its cleaning effect. Too high a concentration may cause corrosion on the metal surface, while too low a concentration may result in poor cleaning effect. Too high a temperature may accelerate the volatilization and decomposition of the degreaser, while too low a temperature may reduce the cleaning efficiency.

3. Pay attention to the degreasing time: If the degreasing time is too short, the grease may not be completely removed, while if it is too long, it may damage the metal surface. The degreasing time should be adjusted according to the specific situation.

4. Subsequent treatment: After degreasing, the metal surface should be rinsed with clean water in time to remove the residual degreasing agent and grease. For some special processes (such as electroplating), further surface treatment is required.

5. Safety protection: Degreasers usually contain corrosive or volatile ingredients. When using them, you should wear protective gloves, masks and goggles to avoid direct contact with the skin and inhalation of steam.

4. Application examples of degreasing agents in metal processing

1. Pre-treatment before painting: Before metal painting, the grease and dirt on the surface must be thoroughly removed to ensure the adhesion and uniformity of the coating. Degreasing agent can effectively clean the metal surface and provide a good foundation for subsequent phosphating, passivation and other treatments.

2. Pre-treatment of electroplating: The electroplating process has extremely high requirements for the cleanliness of the metal surface. Any grease or dirt will affect the quality and bonding strength of the coating. Degreasing agents can remove grease from the metal surface and provide a clean surface for electroplating.

3. Pre-welding treatment: Before welding, grease and dirt on the metal surface will affect the welding quality and the strength of the weld. Degreasing agent can clean the welding area and ensure the smooth progress of the welding process.

4. Precision parts processing: Precision parts have extremely high requirements for surface cleanliness. Any tiny grease or dirt may affect the performance of the parts. Degreasing agents can thoroughly clean precision parts to ensure their quality and reliability.

5. Environmental protection and sustainable development of degreasing agent

With the increasing awareness of environmental protection, the environmental performance of degreasers has received more and more attention. Traditional solvent-based degreasers contain volatile organic compounds (VOCs), which are harmful to the environment and human health. Therefore, the development and use of environmentally friendly degreasers (such as water-based degreasers and bio-enzyme degreasers) has become a trend. These degreasers not only have efficient cleaning capabilities, but are also environmentally friendly and meet the requirements of sustainable development.

VI. Conclusion

Degreasing agents are indispensable chemicals in metal processing, and their selection and use directly affect the quality and performance of the product. By rationally selecting degreasing agents, optimizing the use method and paying attention to safety protection, the efficiency and quality of metal processing can be effectively improved. At the same time, with the improvement of environmental protection requirements, the development and use of environmentally friendly degreasing agents will become an important direction for future development.