Optimization of extreme pressure lubrication performance of cutting fluid in titanium alloy processing
Publish Time: 2025-04-09
Titanium alloy is widely used in aerospace, medical equipment and high-end equipment manufacturing due to its high strength, corrosion resistance and excellent high temperature resistance. However, these characteristics also make titanium alloy a typical difficult-to-process material, which is prone to high temperature, rapid tool wear and reduced surface quality during cutting. As a key medium for improving processing performance, the optimization of extreme pressure lubrication performance of cutting fluid is crucial to improving titanium alloy processing efficiency and extending tool life.
One of the main challenges in titanium alloy processing is the high temperature and high pressure environment in the cutting zone. Due to the low thermal conductivity of titanium alloy, cutting heat is difficult to conduct and dissipate quickly, resulting in a sharp increase in local temperature, aggravating diffusion wear and oxidation wear of the tool. At the same time, the high chemical activity of titanium alloy makes it easy to react chemically with the tool material at high temperature to form built-up edge, further deteriorating processing conditions. Therefore, traditional lubrication methods are often difficult to meet the needs, and the application of extreme pressure (EP) additives has become the core means to improve the performance of cutting fluid. Extreme pressure additives usually contain active elements such as sulfur, phosphorus, and chlorine. They can react chemically with metal surfaces under high temperature and high pressure conditions to form a lubricating film with low shear strength, thereby reducing friction and tool wear.
When optimizing extreme pressure lubrication performance, the selection and ratio of additives are crucial. Sulfur-containing compounds such as sulfurized fatty acid esters can form iron sulfide films at high temperatures, significantly reducing the friction coefficient, but excessive use may cause corrosion of machine tools and workpieces. Phosphorus-based additives provide lubrication by forming phosphate films, which are suitable for medium-load processing, but their extreme pressure performance is relatively weak. Although chlorine-based additives have excellent extreme pressure effects, their application is being strictly restricted due to environmental and health risks. Therefore, modern cutting fluid formulations tend to use composite extreme pressure additives to balance lubrication performance and safety through synergistic effects. For example, the sulfur-phosphorus composite system can not only maintain stable lubrication over a wide temperature range, but also reduce the negative effects of a single additive.
In addition to chemical additives, the type of base fluid of cutting fluid also directly affects the extreme pressure lubrication effect. Oil-based cutting fluids excel in heavy-duty cutting due to their high lubricity and film-forming ability, but they have poor cooling performance and are prone to oil fume pollution. Water-based cutting fluids (such as emulsions and semi-synthetic fluids) have outstanding cooling effects, but they need to be supplemented with extreme pressure additives to make up for the lack of lubrication. In recent years, the advancement of microemulsification technology has enabled water-based cutting fluids to form a more stable lubricating film, gradually replacing some oil-based products in titanium alloy processing. In addition, the introduction of nano-additives such as molybdenum disulfide (MoS₂) or graphene has further improved the extreme pressure performance of cutting fluids. These nanoparticles can form a physical adsorption film on the friction surface, which works together with the chemical lubricating film to significantly reduce the direct contact between the tool and the workpiece.
The coordinated optimization of processing parameters and cutting fluid application methods should not be ignored. In the efficient processing of titanium alloys, the use of high-pressure cooling (HPC) or minimal quantity lubrication (MQL) technology can significantly improve the penetration ability of cutting fluids and ensure the effectiveness of the lubricating film under high temperature and pressure. High-pressure cooling delivers cutting fluid directly to the cutting zone through high-speed jets, which not only enhances the cooling effect, but also effectively washes away chips and reduces secondary friction. MQL technology, on the other hand, achieves precise lubrication while reducing the amount of cutting fluid by atomizing a small amount of cutting fluid, which is especially suitable for occasions with strict environmental requirements.
Environmental protection and health issues are also factors that must be weighed in the optimization of extreme pressure lubrication. Traditional chlorine- and sulfur-containing additives may pose a threat to the health of operators, and the cost of waste fluid treatment is high. Therefore, the development of new environmentally friendly extreme pressure additives (such as borates or ionic liquids) has become a research hotspot. These substances are more degradable while providing sufficient lubrication, and comply with increasingly stringent environmental regulations.
In summary, optimizing the extreme pressure lubrication performance of cutting fluid in titanium alloy processing requires comprehensive design from multiple dimensions such as additive chemistry, base fluid formulation, nanotechnology and process application. In the future, with the improvement of environmental protection requirements and the advancement of processing technology, cutting fluid solutions that combine high performance and sustainability will become the mainstream direction of industry development.
