Aone Titanium Metal Materials
Titanium alloy cutting characteristics
1. The deformation coefficient is small:
This is a remarkable feature of titanium alloy machining, and the deformation coefficient is less than or close to 1. The distance of the sliding friction of the chips on the rake face is greatly increased, accelerating tool wear.
2, high cutting temperature:
Since the thermal conductivity of titanium alloy is very small (only equivalent to 1/5 to 1/7 of 45 steel), the contact length between the chip and the rake face is extremely short, and the heat generated during cutting is not easily transmitted, concentrated in the cutting zone and The cutting temperature is high in a small range near the cutting edge. Under the same cutting conditions, the cutting temperature can be more than doubled when cutting 45 steel.
3. The cutting force per unit area is large:
The main cutting force is about 20% smaller than that when cutting steel. Since the contact length between the chip and the rake face is extremely short, the cutting force per unit contact area is greatly increased, which is liable to cause chipping. At the same time, due to the small elastic modulus of the titanium alloy, bending deformation is easily generated under the action of radial force during processing, causing vibration, increasing tool wear and affecting the accuracy of the part. Therefore, the process system is required to have better rigidity.
4, the chill phenomenon is serious:
Due to the high chemical activity of titanium, it is easy to absorb oxygen and nitrogen in the air to form a hard and brittle outer skin at high cutting temperatures; at the same time, plastic deformation during cutting also causes surface hardening. The chilling phenomenon not only reduces the fatigue strength of the part, but also aggravates the tool wear, which is an important feature when cutting titanium alloy.
5, the tool is easy to wear:
After the blank is processed by stamping, forging and hot rolling, it forms a hard and brittle uneven skin, which is easy to cause chipping, which makes the removal of hard skin the most difficult process in titanium alloy processing. In addition, due to the strong chemical affinity of the titanium alloy for the tool material, the tool is prone to bond wear under conditions of high cutting temperature and large cutting force per unit area. When turning titanium alloy, sometimes the wear of the rake face is even more serious than the flank; when the feed rate f<0.1 mm/r, the wear mainly occurs on the flank face; when f>0.2 mm/r, the front The flank will wear out; when using carbide cutters and semi-finished vehicles, the wear of the flank face is preferably VBmax < 0.4 mm.
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