In the milling process of Dongguan cnc processing plant, an important characteristic of titanium alloy is its extremely poor thermal conductivity. Due to the high strength and low thermal conductivity of titanium alloy materials, extremely high cutting heat (up to 1200°C if not controlled) is generated during processing. The heat is not discharged with the chips or absorbed by the workpiece, but is concentrated on the cutting edge. Such high heat will greatly shorten the tool life. Mechanical processing adopts special processing technology, it is possible to improve the performance and life of the tool (using the correct processing technology to control the temperature, the temperature can be reduced to 250 ~ 300 ℃). Reduce heat generation: reducing the radial and axial engagement of the tool and the workpiece can control the generation of cutting heat. For titanium alloys, the adjustment period for speed, feed rate, and radial and axial joints is very short before the build-up due to overheating. In order to achieve proper tool life, the maximum "joining arc length" of 15% is required for machining titanium alloys, compared with 50% to 100% when machining ordinary steel. Reducing the contact arc length can increase the cutting speed and increase the metal removal rate without losing tool life.
Dongguan cnc processing plant uses tools with an entry angle of 45° or chip thinning, which can increase the contact length between the cutting edge of the tool and the chip, thereby reducing local high temperatures, extending the life of the cutting edge, and also allowing higher cutting speeds. Blade geometry design: When cutting titanium alloys, the use of peripheral grinding blades is essential to minimize the cutting pressure and friction with the machined surface. The blade geometry must be positive, but this is not enough to ensure optimal performance. If a small initial angle with higher strength is used in order to strengthen the first part of the cutting edge, then a larger secondary angle (to obtain a larger front chamfer) is the best for enhancing the compression resistance of the insert and prolonging the tool life. Geometric design. In addition, slight passivation also helps to protect the cutting edge, but the size of the passivation must be coordinated with the cutting process and maintain tight tolerances. When processing titanium alloys, it is necessary to use a sharp cutting edge to cut the material, but the cutting edge is too sharp to easily cause chipping and shorten the tool life. Proper passivation can protect the cutting edge and avoid premature chipping. The correct blade geometry parameters can reduce the stress and pressure on the tool material, make the tool longer life and improve processing efficiency.
The cutting angle of the cutter body and the blade must be a positive angle to obtain a progressive cutting effect, and to avoid impact on the entire cutting edge during cutting and failing to obtain the desired shearing effect. If this is not done, the structure of the workpiece may be deformed, making processing impossible. Cavity milling and spiral interpolation milling
When machining cavity milling and spiral interpolation milling, internal cooling tools must be used. If possible, constant pressure coolant should be used. This is especially important for deep cavity or deep hole machining. When processing deep cavities, the use of high-density cemented carbide extension tools with modular cutting heads can increase rigidity and reduce flexural deformation to obtain the best processing results. The function of the coolant is to remove chips from the cutting area and avoid secondary cutting that may cause early tool failure. At the same time, the coolant also helps to reduce the temperature of the cutting edge, reduce geometric deformation of the workpiece, and extend the life of the tool. Spiral interpolation milling holes with milling cutters can reduce the use of other tools (such as drills, etc.) in the tool magazine. A milling cutter with one diameter can be used to process different sizes of apertures.
Machining As the application of titanium alloys in the aerospace industry continues to grow, cutting technologies that support efficient processing of titanium alloys are also constantly evolving. Due to the large demand for the processing capacity of titanium alloy parts, those workshops or manufacturers that use the most effective processing technology will benefit first. Internal integration produces new solutions. Allegheny Technologies is a multi-field manufacturer. Its business divisions include both metal smelting and metal cutting. The combination of these two fields enables the company to develop new advanced materials (such as titanium alloys) for processing. Method has advantages. ATI Stellram is a business unit of ATI Metalworking Products, a subsidiary of Allegheny Technologies. It is responsible for testing all new materials developed by ATI Allvac to determine the best insert design, tool geometry, substrate and coating structure. As well as cutting parameters, these new materials can be processed cost-effectively before they are publicly marketed. In addition, as a representative of Allvac, Stellram is a major aerospace manufacturing company and a first-class supplier of aerospace machinery parts, which can meet the common needs of workpiece materials and cutting tools.
The comprehensive understanding of the inherent structure of the material gives ATI Stellram an advantage in the design of the unique formula of the tool matrix. One of its achievements is the X-Grade technology. According to ATI Stellram, this technology has been proven to be a reliable tool for processing difficult-to-process materials. Program. Through research and development of X-Grade technology, a new cemented carbide grade has been produced, which can effectively cut difficult-to-machine materials with extremely high metal removal rates under unstable processing conditions. X-Grade blade technology (substrate and coating) X-Grade blade adopts a ruthenium/cobalt alloy matrix, which can resist the generation and expansion of thermal cracks, and can obtain a higher metal removal rate. The matrix has a strong crystal bonding matrix structure, thereby improving the toughness of the cutting edge. According to ATI Stellram, the matrix material combined with new tool geometries and coatings can provide an excellent tool combination for machining aerospace alloys.
The use of X-Grade blades can achieve: ①The metal removal rate is increased by 1 time; ②The tool life is increased by 3 times; ③The surface finish of the processing is increased by 30%. Available X-Grade inserts include 3 grades (X400, X500 and X700), each of which is designed for specific difficult-to-cut machining. They can use standard blade types, and most of them can be installed in the blade groove of the standard blade body. But ATI Stellram said that the best solution is to use specially designed tools to optimize the performance of X-Grade blades.
The groove design of these tools in the Dongguan cnc processing plant can achieve maximum chip evacuation, enhanced geometry and optimal cooling. The two tools in this series include: ①7710VR anti-rotation button milling cutter: equipped with round inserts and with a patented locking indexing system to prevent the insert from shifting at high feedrate cutting; ②7792VX high-feed milling cutter: similar to traditional cutters Compared with, the metal removal rate can be increased by 1 times. In addition to high-feed surface milling, the 7792VX series tools can also be used for cavity milling, slot milling and plunge milling. Since the cutting force is directly transmitted to the spindle in the axial direction, it can reduce spindle friction and improve cutting stability.
A case study of aerospace titanium alloy parts processing
The following are two examples of machining aerospace titanium alloy parts using ATI Stellram cutters and X-Grade blades. (1) Processing example 1 Part to be processed: Titanium alloy outer cover (military) Workpiece material: Ti-6Al-4V (Allvac Ti-6-4 alloy) Workpiece size: 110"×18" Processing description: Use XDLT- ATI Stellram 7792VX high-feed milling cutter with D41 indexable inserts for machining, and the tool life for rough milling is 156 minutes. Milling cutter: C7792VXD12-A3.00Z5R; number of slots: 5 inserts: XDLT120508ER-D41; grade: X500 (designed with X-Grade technology) axial cutting depth ap: 0.080" radial cutting width ae: 2.100" cutting speed vc ：131sfm Feed per tooth fz: 0.023ipt Feed rate: 19.2ipm Tool life: 156 minutes per indexing (each blade can index 4 times).
(2) Processing example 2:
Parts to be machined: Turbine blades of military aircraft (new application) Workpiece material: All titanium alloy Blade size: 23.6"×11.8" Machining description: ATI Stellram 7710VR milling cutter with anti-rotation blade is used to process the propeller blade, rough milling The tool life reaches 110 minutes. Milling cutter: C7710VR12-A2.00Z5R; number of slots: 5 inserts: RPHT1204MOE-421-X4; grade: X700 (designed with X-Grade technology) axial cutting depth ap: 0.080"～0.100" radial cutting width ae: 0.800"～1.37" cutting speed vc: 265sfm feed per tooth fz: 0.0086ipt feed rate: 21.8ipm, tool life: 110 minutes per index (each insert can index 4 times).