Cutting fluids are widely used in cutting processes due to their functions such as cooling, lubrication, cleaning, and rust prevention. The cutting fluid is often deteriorated, smelly, corroded, produced foam, and the operator's skin is allergic in use. The following is a talk about the problems and countermeasures in the use of cutting fluid based on our practical experience. 1. The problem of cutting wave deterioration and odor The main reason for the deterioration and odor of cutting fluid is that it contains a large number of bacteria, mainly including aerobic and anaerobic bacteria. Oxygen consuming bacteria live in environments with minerals, such as water, concentrated cutting fluid, and oil leaked from machine tools. Under aerobic conditions, they split into two every 20-30 minutes. Anaerobic bacteria grow in an environment without oxygen, splitting into two per hour, metabolizing and releasing SO2, giving off a foul egg odor, and turning the cutting fluid black. When the bacteria in the cutting fluid exceed 106, the cutting fluid will become odorous. (1) Bacteria mainly enter the cutting fluid through the following channels: 1) During the preparation process, bacteria invaded, such as bacteria in the water used to prepare cutting fluid. 2) Bacteria in the air enter the cutting fluid. 3) The transportation between workpiece processes causes infection of cutting fluid. 4) Bad habits of operators, such as littering dirty things. 5) Poor cleanliness of machine tools and workshops.
(2) Methods for controlling bacterial growth 1) Use high-quality and stable cutting fluids. 2) Preparing a concentrated solution with pure water not only makes it easy to prepare, but also improves the lubricity of the cutting fluid, reduces the amount of chips taken away, and prevents bacterial erosion. 3) When using, it is necessary to control the ratio of concentrated solution in the cutting fluid to not be too low, otherwise it may cause bacterial growth. 4) Due to the presence of bacteria in the oil used in the machine tool, it is necessary to minimize the mixing of oil leaked from the machine tool with cutting fluid. 5) When the pH value of the cutting fluid is between 8.3 and 9.2, bacteria are difficult to survive, so new cutting fluid should be added in a timely manner to increase the pH value. 6) Keep the cutting fluid clean and avoid contact with dirt such as oil, food, tobacco, etc. 7) Frequent use of fungicides. 8) Keep the workshop and machine tools clean. 9) If the equipment does not have a filtering device, the floating oil should be regularly skimmed and dirt removed.
2. Corrosion problem of cutting fluid (1) Causes of corrosion 1) The proportion of concentrated solution in cutting fluid is relatively low.
2) The pH value of the cutting fluid is too high or too low. For example, when pH>9.2, it has a corrosive effect on aluminum. Therefore, the appropriate pH value should be selected based on the metal material. 3) Contact with dissimilar metal materials. 4) Use paper or wood pad to place the workpiece. 5) Component stacking. 6) The number of bacteria in the cutting fluid exceeds the standard. 7) The humidity in the working environment is too high. (2) Methods for preventing corrosion 1) Prepare cutting fluid with pure water, and the proportion of cutting fluid should be used according to the recommended values in the cutting fluid manual. 2) If necessary, use anti rust fluid. 3) Control the number of bacteria and avoid their production. 4) Check humidity.
