Problems that occur with cutting fluids during use and their solutions

Thread Content

Cutting fluids are widely used in machining processes due to their functions of cooling, lubrication, cleaning, and rust prevention. During use, cutting fluids often experience problems such as deterioration and odor, corrosion, foaming, and skin allergies in those who handle them. Based on our practical experience in work, we will discuss these issues associated with the use of cutting fluids and the corresponding solutions. I. The problem of deterioration and odor formation in cutting fluids. The main reason for the deterioration and odor formation in cutting fluids is the presence of a large number of bacteria in them; these bacteria mainly include aerobic and anaerobic bacteria. Oxygen-consuming bacteria live in mineral-rich environments such as water, concentrated cutting fluids, and oil leaking from machine tools; under aerobic conditions, they divide into two cells every 20 to 30 minutes. Anaerobic bacteria, on the other hand, live in oxygen-free environments; they divide into two cells per hour, and their metabolism releases SO2, which gives off an odor similar to that of rotten eggs and causes the cutting fluid to turn black. When the bacteria count in the cutting fluid exceeds 106, the cutting fluid becomes smelly. (1) Bacteria enter the cutting fluid mainly through the following channels: 1) Bacteria invade during the preparation process, such as when bacteria are present in the water used to prepare the cutting fluid. 2) Bacteria in the air enter the cutting fluid. 3) Transfer of workpieces between processes causes contamination of the cutting fluid. 4) Poor *habits of the operator, such as littering. 5) Poor cleanliness of the machine tools and the workshop. (2) Methods to control bacterial growth 1) Use cutting fluids of high quality and good stability. 2) Preparing a concentrate with pure water is not only easy, but it also improves the lubricity of the cutting fluid, reduces the amount of chips carried away, and prevents bacterial degradation. 3) When in use, it is necessary to keep the concentration ratio of the concentrate in the cutting fluid from being too low, otherwise it can facilitate bacterial growth. 4) Since the oil used in the machine tool contains bacteria, it is necessary to minimize the mixing of oil leaking from the machine tool into the cutting fluid. 5) When the pH value of the cutting fluid is between 8.3 and 9.2, bacteria find it difficult to survive; therefore, new cutting fluid should be added promptly to raise the pH value. 6) Keep the cutting fluid clean; do not allow it to come into contact with dirty oil, food, tobacco, or other contaminants. 7) Fungicides are used frequently. 8) Keep the workshop and machine tools clean. 9) If the equipment does not have a filtering device, floating oil should be removed regularly, and dirt should be cleared away. II. Corrosion issues with cutting fluids (1) Reasons for corrosion 1) The proportion of concentrated substances in the cutting fluid is too low. 2) The pH value of the cutting fluid is too high or too low. For example, when PH > 9.2, it is corrosive to aluminum. Therefore, the appropriate pH value should be selected based on the metal material. 3) Contact between dissimilar metal materials. 4) Place the workpiece on paper or wood. 5) Stacking of components. 6) The bacterial count in the cutting fluid is above the standard. 7) The humidity in the working environment is too high. (2) Methods for preventing corrosion: 1) Prepare the cutting fluid using pure water, and use it in the proportions recommended in the instructions provided for that cutting fluid. 2) Use rust preventive solution when necessary. 3) Control the number of bacteria to prevent their formation. 4) Check the humidity, and make sure to keep the humidity in the working environment within an appropriate range. 5) It is necessary to prevent the cutting fluid from being contaminated. 6) Avoid contact between dissimilar materials, such as aluminum and steel, cast iron (containing magnesium) and copper, etc. III. The problem of foam formation When using cutting fluid, excessive foam may sometimes form on its surface. (1) Main reasons for foam formation: 1) The liquid level of the cutting fluid is too low. 2) The flow rate of the cutting fluid is too high; the bubbles do not have time to escape, so they accumulate more and more, resulting in a large amount of foam. 3) There are too many right angles in the sink design, or the angle of the cutting fluid nozzles is too straight. (2) Methods to avoid foam formation: 1) In a centralized cooling system, the pipelines should be connected in series at different stages, with the pipelines closer to the cooling tank having lower pressure. 2) Ensure that the level of the cutting fluid is not too low; check its level regularly and top it up as needed. 3) Control the cutting fluid flow rate so that it is not too fast. 4) When designing the tank, care should be taken to avoid too many right angles in it. 5) When using cutting fluid, care should be taken to ensure that the angle of the cutting fluid nozzle is not too straight. IV. Issues of skin allergy in operators (1) Main causes of skin allergy in operators 1) Too high pH value. 2) Components of the cutting fluid. 3) Insoluble metals and oils used in machine tools. 4) The concentration ratio of the concentrate used is too high. 5) Protective suspension layers on the surface of the cutting fluid, such as odor-sealing layers and anti-foam layers. Fungicides and dirty cutting fluids. (2) At work, to prevent skin allergies in operators, the following points should be observed: 1) Operators should apply protective oil, wear work clothes and gloves, and take care to avoid direct contact between their skin and the cutting fluid. 2) The concentration ratio of the cutting fluid concentrate must be used in accordance with the recommended values for that cutting fluid. 3) Fungicides should be used at the dosage specified in the instructions. Furthermore, fluororubbers and lip rubbers deform little under the influence of cutting fluids, so they can be given priority when used as machine tool seals. To prevent deformation, the fat content in the rubber used for machine tool seals should generally be greater than 35%. Additionally, to effectively prevent the cutting fluid from causing the machine tool paint to peel off, epoxy paint or polyester paint can be chosen. In short, when using cutting fluids in normal production, by paying attention to the issues mentioned above, it is possible to avoid unnecessary financial losses and improve production efficiency effectively. The Jieyouwang cutting fluid purification equipment can be used to extend the lifespan of cutting fluids, helping to achieve environmental protection and cost savings among other benefits. For more information on lubricants, please visit the Jieyouwang oil filtration machine website; you can find it by searching for “Jieyouwang” on Baidu. The site contains a wealth of information on the use, maintenance, and recycling of hydraulic oils. In general, this approach allows hydraulic oils to be used for over five years, keeping them in a condition similar to new oils. There are also videos on hydraulic oil filtration on the site, which represent valuable tools for maintaining hydraulic equipment and extending its lifespan. Please use this information as a reference!