Titanium alloys are increasingly used in the aviation manufacturing industry due to their high strength, good mechanical properties and strong corrosion resistance. As the proportion of titanium alloys in aircraft continues to increase. The CNC machining efficiency of titanium alloy aviation structural parts has an increasing impact on aviation manufacturing companies. Titanium alloys are difficult-to-process materials, with a relative machinability of 0.15 to 0.25, and a machining efficiency of only 10% of that of aluminum alloys.
Therefore, the low machining efficiency of titanium alloy aviation structural parts has seriously restricted the mass production of modern aircraft. Realizing efficient machining of titanium alloy aviation structural parts has become a topic of common concern for aviation manufacturing companies, CNC equipment manufacturers and tool manufacturers.
Titanium Alloy Cutting Processing Performance
Titanium alloy has the characteristics of good mechanical properties, strong corrosion resistance and low specific gravity. However, in processing, the cutting performance of titanium alloy is very poor, which is mainly manifested in the following aspects:
- High cutting force. Titanium alloy material has high strength, and the cutting resistance generated during cutting is large, resulting in a large amount of cutting heat generated at the cutting edge.
- Low thermal conductivity. Titanium alloy has low thermal diffusivity, and a large amount of cutting heat is concentrated in the cutting area.
- High tip stress. Titanium alloy has low plasticity, and the chips produced by processing are very easy to bend, resulting in a short contact length between the chips and the front cutting edge. Therefore, the force per unit area on the cutting edge increases, causing stress concentration at the tip of the tool.
- High friction. The elastic modulus of titanium alloy is small, resulting in increased friction between the front and rear cutting edges.
- High chemical activity. At high cutting temperatures, titanium elements can easily react chemically with gases such as hydrogen, oxygen, and nitrogen in the air to form a surface hard layer, which accelerates tool wear.
Titanium Alloy High Efficiency Processing Equipment
In order to meet the efficient processing of titanium alloy structural parts, new titanium alloy processing equipment presents the following development trends:
- Large torque. Titanium alloy has high strength and the cutting force is very large during processing. An obvious feature of titanium alloy processing machine tools is the large spindle torque and swing angle torque.
- Application of electric spindles. High-power and high-torque electric spindles have been applied to titanium alloy processing.
- Horizontal machining centers are applied to titanium alloy processing. Horizontal machining centers are convenient for chip removal, which is conducive to improving processing efficiency and processing quality. Interchangeable workbenches are easy to realize multi-station processing and form flexible production lines, improving equipment utilization.
- High-pressure internal cooling. In titanium alloy processing, the cutting heat is concentrated on the tip of the tool, which is easy to cause tool wear or damage. High-pressure internal cooling can accurately spray to the cutting area to take away the cutting heat.
Titanium Alloy High Efficiency Machining Milling Cutter
Titanium alloy has poor machinability, and the cutting speed of traditional machining methods generally does not exceed 60m/min. Rough machining of titanium alloy mainly uses large cutting depth, low speed and low feed to obtain the maximum metal removal rate. Finishing uses PVD coated carbide tools for high-speed milling with small cutting width and large cutting depth to obtain efficient cutting. Therefore, titanium alloy machining tools are mainly improved around how to avoid vibration during strong cutting, reduce cutting force and reduce cutting temperature.
SAMHO recently launched the SHTI series, which specializes in machining titanium alloy materials. The tool life is 8-10 hours. It has been promoted in China and many customers are using it.
Titanium Alloy High-efficiency Machining End mill Cutter
Titanium Alloy Face Milling Processing
Titanium alloy face milling
When face milling titanium alloy parts, a milling method with small cutting depth and large feed is used to achieve efficient processing. The principle of high feed milling is to reduce the main deflection angle of the tool so that the tool can still maintain a small chip thickness at a very high feed. In order to reduce the cutting force at high feed, a large feed amount can be obtained at a low cutting speed, and the metal removal rate per unit cutting depth can be increased. At the same time, the cutting force is partly vertically upward, the tangential force is small, and the power consumption is also small. This processing method does not require high power and rigidity of the machine tool, and is widely used.
SHTI series end mills can meet the face milling of titanium alloy materials.
Titanium Alloy Slot Processing
The slot cavity is a main feature of titanium alloy aviation structural parts, with high material removal rate and large workload. Therefore, slot cavity processing is the key to achieving efficient processing of titanium alloy parts. Powerful cutting with large cutting depth, low speed and low feed to obtain maximum metal removal rate is an effective method for rough processing of titanium alloys. At present, the corn milling cutter is the most efficient and widely used powerful milling tool for rough processing of titanium alloys.
The SHTI series also has long neck end mills, which are specially designed for deep cavity processing.
Round Corner Processing Technology
In order to reduce the weight of the aircraft, the fillets at the corners of the slots of the aircraft structural parts are usually smaller and need to be processed with a smaller diameter milling cutter. Due to the sudden change in cutting volume at the fillet, the cutting force changes greatly. In the case of a sudden change in cutting force, the tool easily vibrates and even breaks. This leads to severe tool wear and low processing efficiency.
Plunge milling is the best way to solve the corner processing efficiency. Plunge milling has less vibration than conventional milling, and the cutting method is efficient in removing corner allowances. Most of the corner allowances can be removed by using plunge milling tools of different diameters. Then use an end mill to remove the residues produced by plunge milling, which can greatly improve the processing efficiency.
Precision Side Milling Technology
When finishing the side wall, the discontinuous nature of milling is used to achieve the purpose of high-speed cutting. This improves the surface quality and processing efficiency of the parts. When finishing the side, due to the small cutting width, the cutting time for each rotation of the cutter teeth is very short, that is, the cooling time is very long. Under the condition of sufficient cooling, the cutting temperature can be effectively controlled. Therefore, the cutting speed can be greatly increased to improve the processing efficiency. Use PVD-coated solid carbide milling cutters or super-dense tooth carbide milling cutters for high-speed cutting and finishing of titanium alloys. This can greatly improve the processing efficiency and processing accuracy.
