Microbial management of water-based cutting fluids
February 20, 2022
Water-based cutting fluid contains nutrients necessary for the growth and reproduction of microorganisms, such as extreme pressure lubricants such as grease, sulfur, phosphorus, nitrogen contained in ammonia and amide chemicals, oxygen in the air, etc., as well as moisture and suitable Such an environment is very suitable for the survival and reproduction of microorganisms. The types of microorganisms in water-based cutting fluids include bacteria and fungi. The main bacteria are Escherichia coli, Pneumococcus, Proteus, Pseudomonas, Salmonella, and Staphylococcus. Fungi are mainly molds and yeasts. Under suitable conditions, these microorganisms divide every 20-30 minutes and grow geometrically. The number of bacteria produced within 24 hours can reach tens of millions. On weekends or holidays, the cutting fluid is in a static state, which promotes the reproduction of anaerobic bacteria. , so that the cutting fluid will spoil within 1-2 days.
The hazard of microbial reproduction in water-based cutting fluids 1. Make the cutting fluid smelly, gray and black in color. 2. The acid produced by bacteria causes the pH value to drop and the rust prevention performance to deteriorate. 3. The composition of the cutting fluid is decomposed, which reduces the cutting quality and shortens the tool life. 4. The scum or sludge-like viscous material is generated, which affects the movement of the machine tool and causes the liquid supply pipeline, liquid supply pump and filter to be blocked. 5. The surfactant is decomposed, resulting in demulsification and separation of the cutting fluid. 6. It produces foul odor, pollutes the environment and affects the health of the operator.
Measures to inhibit the reproduction of microorganisms 1. Select cutting fluid with less microbial nutrients, and use appropriate amount of antiseptic bactericide to prevent microbial reproduction. 2. When adding new liquid, first completely remove the chips and foreign objects in the liquid supply system around the machine tool, and fully disinfect with bactericide. 3. Use tap water or soft water for dilution, avoid hard water with too much salt. 4. Regularly check the PH value. When the PH value drops, add new liquid or PH value enhancer to keep the PH value around 9. 5. Regularly check the use concentration to make the cutting fluid work under the specified normal concentration. 6. Regularly check the reproduction of microorganisms. When the bacteria exceed 105/ml, fungicides should be added to control their reproduction. 7. Pay attention to prevent oil leakage from mixing, and set up a device that can quickly remove oil leakage. 8. Adopt effective chip removal method to avoid long-term deposition of chips, especially fine chips, in the fuel tank. 9. When waiting for a long time such as holidays, increase the concentration and PH value of the cutting fluid and add a fungicide before waiting.
