Application of vegetable oil cutting fluid in machining titanium alloy parts

Some principles of titanium alloy cutting, according to the nature of titanium alloy and the characteristics of the cutting process, processing should consider the following aspects:

As far as possible to use carbide tools, such as tungsten cobalt tungsten carbide and titanium alloy chemical affinity is small, good thermal conductivity, strength is also high. Low speed intermittent cutting can choose the impact resistant ultra-fine grain carbide, forming and complex tools can be used high speed steel with good high temperature performance. Adopt smaller front Angle and larger back Angle to increase the contact length between the chip and the front tool face, reduce the friction between the workpiece and the back tool face, and adopt arc transition edge to improve the strength and avoid burning and breaking of the sharp Angle. Keep the blade sharp to ensure smooth chip removal and avoid sticking chips. The cutting speed should be low to avoid too high cutting temperature; Moderate feed, too large easy to burn the knife, too small because the blade in the work hardening layer and wear too fast; The cutting depth can be large, so that the tool tip works below the hardened layer, which is conducive to improving the tool durability. When processing, the choice of cutting fluid is crucial, chlorine will lead to increased surface hardening, resulting in intergranular corrosion, so water-based products are best without chlorine.

Only in terms of cutting fluid, the selection of plant oil-based cutting fluid is the best solution. Vegetable oil based cutting fluid. In machining applications, the introduction of plant oil-based coolants can improve the mechanical cutting performance. As a proven technology, vegetable oils have been known to have super lubricating properties since the 1960s. At that time, the choice of machining lubricants was limited to mineral oil-based coolants containing various additives. Today, a new generation of emulsifiers and stabilizers make plant-based coolants practical in a variety of machining applications. Due to the use of such coolants in the processing process, the productivity is also greatly improved. It is reported that it is common to increase productivity by 20% to 30%. In addition, the service life of the tool has also been increased by more than 50%. Since the 1990s, VASCO series of plant oil-based cutting fluids and VASCOMILL series of plant oil-based cutting oils have been launched. Efforts are put to the test in processing stability and maintaining high lubricity during processing. Because the plant oil-based cutting fluid has a bipolar molecular structure, its lubrication effect is better than that of mineral oil-based cutting fluid, which significantly improves the cutting speed and prolongs the durability of the tool. Some companies report that the service life of the tool has even been doubled. In addition, the stability of the machining process is also higher than that of other cutting fluids, due to slow wear, thus ensuring that the processing accuracy of the last workpiece processed in batches is the same as that of the first workpiece.

The high lubrication performance of vegetable oil is determined by the basic composition of vegetable oil molecules and their own chemical structure. The lubricating properties of vegetable oil-based coolants result from the inherent "oiliness" of the vegetable oil composition, which is directly the result of the "clever molecules" of the vegetable oil. These molecules are long, heavy and bipolar, meaning they have opposite charges at each end of the molecule. The two "extremes" of the molecule have a strong chemical affinity for the metal surface, and they stick to the metal surface like tiny magnets. The vegetable oil molecules are arranged vertically, tightly and evenly on the surface of the metal, resulting in a thick, strong and durable lubricating film on its surface.

Comparison of film arrangement between mineral oil base and plant oil base. In contrast, the molecules of mineral oil are polar free. Their distribution on the surface of the titanium metal is irregular, so the resulting lubrication layer is relatively weak. The higher the viscosity temperature index of the vegetable oil, the more stable lubrication characteristics can be guaranteed over the operating temperature range. With the increase of processing temperature, the viscosity of vegetable oil decreases more slowly than that of mineral oil. On the contrary, as the temperature decreases, the liquid fluidity of vegetable oil is better than that of mineral oil, which is conducive to separation from chips and workpieces. Moreover, its high melting point is conducive to improving the metal cutting rate, reducing the formation of smoke, and reducing the risk of fire. The size of vegetable oil molecules is very uniform, while the size of mineral oil molecules varies widely. As a result, the physical properties of mineral oils, such as their viscosity at evaporation and at boiling point, are greatly affected, whereas the loss of vegetable oils due to evaporation and atomization is extremely low. This creates a healthy and clean working environment for people.