Discuss the impact of the pH value of processed oils on the causes of metal surface corrosion and methods for its control

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pH value is an important parameter for controlling corrosion in metal machining fluids. A pH value above 9 can protect ferrous metals, but it is not beneficial for protecting non-ferrous metals such as aluminum, brass, and bronze from corrosion. Water hardness affects the balance of the machining fluid; water hardness varies in different geographical areas, and adjusting it can optimize the performance of the machining fluid. Under single-machine conditions, if the pH value is low, the simplest solution is to pour it out and clean it, then add fresh metal machining fluid at the recommended concentration. In the case of a central groove system for processing ferrous metals, the pH value can be adjusted to 8.8–9.2 using appropriate additives. If the pH value is particularly high, it usually means that the metal machining fluid has become contaminated, and it needs to be discarded and replaced with fresh fluid.