The Harm of "Miscellaneous Oil" in Metal Working Fluids
August 14, 2023
Miscellaneous oil refers to the oil that accidentally enters the Metal Working Fluid, which is the main cause of the failure of the metal working fluid. It changes the chemical composition of the working fluid and affects the accurate concentration measurement of the metal working fluid.
There are several sources of miscellaneous oil entering the metalworking fluid 1. Machine tool lubricating oil. This includes hydraulic oil, guide rail oil, spindle lubricating oil, and gear lubricating oil. 2. Enter from the surrounding environment. When the floor or machine tool is cleaned, oil leaks or is flushed into the metal working fluid system.
3. The previous machining process used cutting oil, or the parts were coated with anti rust oil (which is the most troublesome thing), and the parts were brought into the metal working fluid system.
Metal working fluid professionals classify machine tool oil into three states 1. Miscellaneous oil in a free state. When the metal working fluid is stationary or the centralized circulating cooling system is shut down, it floats on the surface of the metal working fluid. 2. Miscellaneous oil in a dispersed state. Mechanically dispersed into the interior of the metal working fluid (if the metal working fluid remains stationary for sufficient time, the oil will float up to the surface). 3. Emulsified miscellaneous oil. These oils enter the metal working fluid system in an emulsified manner and can remain stable for a long time.
The main impact of machine tool oil impurities 1. Produce surface residues on machine tool parts and working environment; 2. Produce smoke and oil mist in the workshop environment; 3. Obstruction of the filtration system's filtration work; 4. Stimulate the reproduction of bacteria and produce odors; 5. Reduced the wetting performance of metal working fluid products, resulting in corrosion of workpieces and iron filings; 6. Reduce the ability of metal working fluid to remove heat; 7. Some miscellaneous oils contain surfactant, which makes metalworking fluid produce foam; 8. If the oil contains active sulfur or thio Zinc phosphate salt, it may cause dermatitis; 9. Difficulty in controlling and measuring the concentration increase of metal working fluids; 10. Causes the loss of wetting agent, reduces the surface smoothness of metal parts and tool life. On machine tools with a high amount of miscellaneous oil, the negative impact of machine tool miscellaneous oil is obvious. In a centralized cooling system, the negative effect of miscellaneous oil is greater. Due to the small amount of oil taken away, it is easy for miscellaneous oil to accumulate. Due to the continuous circulation of the system, the pump also mixes the miscellaneous oil into the metal working fluid system, causing it to disperse or be emulsified. Generally speaking, when the machine tool oil is less than 2%, there are relatively few problems; When it is above 2%, we begin to see bacteria begin to multiply in large numbers; When it exceeds 4%, tool life, part smoothness, oil mist, and surface residue all become issues. The impact of impurities from different sources is also different, and even if the wax containing rust inhibitor is only 0.5%, it can cause serious problems. Machine tool oil contamination should be minimized and removed from the system as soon as possible.
