Biological Stability of Water-Based Cutting Fluids: Progress and Application

The application of cutting fluid in the field of engineering manufacturing has a history of hundreds of years, and it plays a vital role in the processing efficiency and surface quality of parts. Among them, water-based cutting fluid accounts for more than 90% of the consumption of cutting fluid. However, long-term recycling of water-based cutting fluid could easily cause deterioration, and the breeding of bacteria could cause the cutting fluid to fail, increase manufacturing costs, and even endanger the health of workers. Traditional bactericides could improve the biological stability of cutting fluids, but they are toxic to the environment and do not conform to the development trend of low-carbon manufacturing. Low-carbon manufacturing is inevitable and the direction of sustainable manufacturing. The use of nanomaterials, transition metal complexes, and physical sterilization methods on the bacterial cell membrane and genetic material could effectively solve this problem. In this article, the mechanism of action of additives and microbial metabolites was first analyzed. Then, the denaturation mechanism of traditional bactericides on the target protein and the effect of sterilization efficiency were summarized. Further, the mechanism of nanomaterials disrupting cell membrane potential was discussed. The effects of lipophilicity and the atomic number of transition metal complexes on cell membrane penetration were also summarized, and the effects of ultraviolet rays and ozone on the destruction of bacterial genetic material were reviewed. In other words, the bactericidal performance, hazard, degradability, and economics of various sterilization methods were comprehensively evaluated, and the potential development direction of improving the biological stability of cutting fluid was proposed.