In the production of metal products, lubricants are lubricating media used to reduce the frictional resistance of friction pairs and slow down their wear. The lubricant also cools, cleans and prevents contamination of the friction pair. However, the use of lubricants may cause corrosion spots, brown and white contamination spots on the surface of the product, etc., which not only reduces the appearance quality of the product, but also increases the difficulty of subsequent processing, and even affects the performance of the product.

       In order to improve product quality and eliminate spots, it is necessary to study the surface degreasing and cleaning process. The components and properties of lubricants are very important for surface degreasing and cleaning. The pollution spots formed on the metal surface can be divided into three categories according to the substances causing the pollution:

      (1) Oily pollution—oil, grease and fatty acid;

      (2) Water-soluble pollution—organic acid and inorganic acid;

      (3) Solid pollution - oxides, particles and dust, etc.

Commonly used metal surface degreasing and cleaning methods and characteristics are as follows:

      1. Wiping method: general manual operation, suitable for cleaning complex parts and small production.

      2. Brushing method: It can clean the dirt that is not firm on the surface, suitable for small production.

      3. Pickling method: It can clean the oxide skin, organic matter, alkali film and plaque on the metal surface, but it has an erosive effect on the surface.

      4. Alkali cleaning method: The saponification pollution can be removed by the saponification of lye.

      5. Organic solvent cleaning method: Use the organic solvent's ability to dissolve oil and grease to remove dirt, the cleaning time is short, and it does not corrode metals, but most organic solvents are toxic.

      6. Ultrasonic cleaning method: The sound energy of the ultrasonic vibration source is converted into mechanical vibration through the transducer, and the ultrasonic wave is radiated to the cleaning liquid in the tank by cleaning the tank wall, so that the microbubbles in the liquid in the tank can be under the action of sound waves. Vibration is maintained, causing fatigue failure of the dirt layer to be peeled off.

      7. Emulsion cleaning method, electrolytic cleaning method, etc. www.mcwchem.com