Advantages of Long-edge End Mills For Titanium Alloy Processing

The need for optimization of various processing procedures, especially when the processing of chips and difficult-to-machine materials is dominant, HPC technology, which can already be widely used on machine tools, is undoubtedly an extremely attractive choice. The increasing popularity of multitasking machine tools and the new generation of vertical lathes has already highlighted the benefits of HPC machining, especially from the perspective of chip control. As manufacturers increasingly use these machines to process aerospace parts made of difficult-to-machine materials, it becomes more important to eliminate the trouble caused by the accumulation of chips.
Sandvik Coromant CoroMill 690 is a long-edge end mill with high-pressure cooling capability specially designed for processing titanium alloys. The radial cutting edge is composed of many blades, and each blade has a corresponding coolant nozzle to provide high-pressure injection. In the case where the entire axial depth of the milling cutter is not required, a plug can be used instead of the nozzle, which can avoid unnecessary empty injection and loss of cooling pressure.
In the 1880s and 1990s, Sandvik Coromant developed the first generation of high-pressure cooling system Jetbreak. Studies have shown that for demanding machining materials in terms of machinability and chip control, ultra-high pressure, precise direction coolant jets of up to 100 to 1000 bar (1 bar = 105 Pa) have become part of cutting tools. The coolant jet forms a hydraulic wedge between the chip and the cutting edge. As the temperature of the machining area decreases, the contact length of the chip and the cutting edge decreases. Another interesting effect is that the coolant jet affects the curling of the chips, which improves chip control and in some cases leads to chip breaking.
Through the application of non-standard tools, the Jetbreak system has become an ideal solution for materials with poor machinability or difficult chip breaking. The distribution of coolant pressure and the size of the nozzle will have a great influence on the processing effect. By adjusting the jet parameters, different chip curling effects can be obtained, and even the length of the chip can be improved. The practical application of the Jetbreak system is relatively limited, mainly used to solve the problems encountered in the petroleum, aerospace and rolling bearing industries. The Jetbreak system needs to be equipped with a special non-standard tool holder, and the technology is mainly used in vertical lathes.
CoroTurnHP can produce parallel and precise coolant injection, generate a hydraulic wedge between the blade and the chip, affect the formation and flow of the chip and reduce the temperature of the cutting area. The nozzle installed near the cutting edge accurately ejects a high-speed coolant jet, forcing the chips to leave the surface of the blade, cooling and breaking, which is beneficial to chip removal. The standard nozzle size is 1mm, and there are also 0.6~1.2mm sizes for specific optimization applications.
Even if the coolant pressure is as low as 10 bar, HPC technology can still obtain considerable benefits when finishing materials such as steel, stainless steel, aluminum alloy, titanium alloy and high temperature alloy. In addition to higher machining safety brought about by better chip control, HPC can also significantly extend tool life (up to 50%). The use of higher cutting speeds can significantly save production costs. Compared with any other factors, cutting speed has a greater impact on cutting temperature and tool wear. When processing titanium alloys beyond the reasonable processing area, increasing the cutting speed will lead to a sharp reduction in tool life, but this will be improved by increasing the feed in a similar manner. Therefore, by changing the feed rate to improve the metal removal rate becomes more attractive.

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