Discussion on Precision Machining of Titanium Alloys
Aug 12, 2025
Due to titanium alloy's low deformation coefficient, high cutting temperatures, high tool tip stress, and severe work hardening, cutting tools are prone to wear and chipping during machining, making quality difficult to guarantee. So, how should cutting be performed? When cutting titanium alloys, cutting forces are low, work hardening is minimal, and a relatively good surface finish is easily achieved. However, titanium alloys have low thermal conductivity and high cutting temperatures, resulting in significant tool wear and low tool durability. Tungsten-cobalt carbide tools, such as YG8 and YG3, should be selected, as they have low chemical affinity with titanium, high thermal conductivity, high strength, and small grain size.
Chip breaking is a challenge in turning titanium alloys, especially when machining pure titanium. To achieve chip breaking, the cutting edge can be ground into a fully arc-shaped chip flute, shallow in front and deep in the back, narrow in front and wide in the back. This allows chips to be easily discharged, preventing them from entangled on the workpiece surface and causing scratches. Titanium alloy cutting has a low deformation coefficient, a small tool-chip contact area, and high cutting temperatures. To reduce cutting heat generation, the rake angle of the turning tool should not be too large. Carbide turning tools generally have a rake angle of 5-8 degrees. Due to the high hardness of titanium alloy, the back angle should also be kept small to increase the tool's impact resistance, typically 5 degrees. To enhance the tool tip's strength, improve heat dissipation, and enhance the tool's impact resistance, a large negative rake angle is used. Maintaining a reasonable cutting speed (not too high), and using titanium-specific cutting fluid for cooling during machining can effectively improve tool durability. A reasonable feed rate should also be selected.
Drilling is also a common operation, but titanium alloy drilling is challenging, and tool burning and breakage are common. These issues are primarily due to poor drill sharpening, inadequate chip removal, poor cooling, and poor process system rigidity. Depending on the drill diameter, the chisel edge should be narrowed, typically around 0.5 mm, to reduce axial forces and vibration caused by resistance. At the same time, the drill bit's land should be narrowed 5-8 mm from the drill tip, leaving about 0.5 mm to facilitate chip evacuation. The drill bit's geometry must be correctly sharpened, and both cutting edges must be symmetrical. This prevents the drill bit from cutting on only one side, concentrating all the cutting force on one side, causing premature wear and even chipping due to slippage. Always maintain a sharp edge. When the edge becomes dull, stop drilling immediately and resharpen the drill bit.
Continuing to forcefully cut with a dull drill bit will quickly burn and anneal due to frictional heat, rendering the drill useless. This also thickens the hardened layer on the workpiece, making subsequent re-drilling more difficult and requiring more resharpening. Depending on the required drilling depth, the drill bit should be minimized and the core thickness increased to increase rigidity and prevent chipping caused by vibration during drilling. Practice has shown that a φ15 drill bit with a 150 mm diameter has a longer lifespan than one with a 195 mm diameter. Therefore, the correct length is crucial. Judging from the two common machining methods mentioned above, machining titanium alloys is relatively difficult. However, with careful processing, high-quality precision parts can be produced, such as titanium alloy parts for aerospace equipment.
Precision machining in the aerospace industry places high demands on materials. This is partly due to the special requirements of aviation equipment, but more importantly, due to the environmental impact of aerospace. Because of these special environmental conditions, standard commercially available materials cannot meet these requirements, necessitating the use of specialized alternatives. Now, let me introduce a relatively common material: titanium alloy, particularly common in aerospace. Why is this material so widely used? It has something to do with its properties. Titanium alloy has a low specific gravity, resulting in a low mass. Its high strength and thermal strength contribute to its hardness, high-temperature resistance, and excellent physical and mechanical properties, such as resistance to seawater, acid and alkali corrosion, making it suitable for use in any environment. Furthermore, its low deformation coefficient has led to its widespread application in industries such as aerospace, aviation, shipbuilding, petroleum, and chemical engineering.
The company boasts leading domestic titanium processing production lines, including:
German-imported precision titanium tube production line (annual production capacity: 30,000 tons);
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The MES system enables digital control and management of the entire production process, achieving product dimensional accuracy of ±0.01μm.
