Factors affecting the machining technology of titanium machining

Factors affecting the machining technology of titanium alloy machining

1 the thermal conductivity is small, the heat dissipation condition is not good, the cutting temperature is increased, the tool wear is accelerated, and the service life is reduced;

2 temperature reaches 600 DEG C, forming a dense oxide layer, the tool has strong effect of wear;

3 titanium alloy elastic modulus is small, the processing time under the radial force action is easy to produce the bending deformation, causes the vibration, increases the cutting tool wear and influence the precision of the work piece;

4 the chemical activity of titanium is large, in the high cutting temperature, easy to contact with the metal, resulting in adhesion, diffusion, aggravate tool wear.

The general principles of machining titanium alloy are:

The titanium alloy has high strength, high thermal strength, good corrosion resistance, low thermal conductivity, low elastic modulus and high chemical activity. According to the characteristics of titanium alloy and the problems in the machining process, the following factors need to be processed:

1 cutting speed should not be too high. Experiments show that the higher the cutting speed, the cutting temperature will increase, which will directly affect the tool wear and life. Therefore, to select the appropriate cutting speed;

2 cutting depth can be large. The smaller effect of cutting depth on cutting temperature, so in the premise of reasonable selection of cutting speed, increasing the cutting depth, can make the tool tip in the work hardening layer, improve the durability of the tool;

3 process system should have sufficient strength. Spindle of the machine tool should have a smaller gap, a small amount of beating; the tool is not easy to extend too long, to maintain sufficient strength; clamping force to be appropriate, not too easy to prevent deformation;

4 filling the full coolant. As the titanium alloy in the processing process, the temperature is very high, the chemical activity is big. In micro cutting, it is easy to burn, so we must fill in the full cutting fluid. Commonly used cutting fluid has the emulsion and the extreme pressure water soluble cutting fluid.

Tool material selection

Due to the thermal conductivity of titanium alloy, low plasticity, prone to hardening, so the machining of titanium alloy should decrease the cutting temperature and reducing the two bond, with good red hardness, high bending strength, good thermal conductivity, and titanium alloy affinity difference tool material, general selection of hard alloy cutter. Commonly used carbide tool materials are YG8, YG3, YG8W, YG10H, YG6A, YS2T, YGRM and YD15, etc..

1 rough machining, should choose YG8, YG8W, YG10H, YG6A, etc..

2 finish machining, the amount of cutting is small, can choose YG8W, YD15, etc..

Tool geometric parameters and cutting parameters selection

Outside the circular tool as an example.

1 rough, 3 degrees to 7 degrees before the angle, after the angle of 8 degrees to 15 degrees, the corner radius is 0.5 ~ 1 mm; the cutting speed is 25 ~ 38 m/min, the cutting depth of 3 ~ 5 mm, feed 0.3 ~ 0.5 mm/r.

2 finishing, 10 degrees to choose the angle of 15 degrees, after the angle of 8 degrees to 15 degrees, the corner radius is 0.3 ~ 0.5mm; the cutting speed is 50 ~ 75 m/min, the cutting depth of 0.2 ~ 0.5 mm, feed rate of 0.1 ~.0.15 mm/r.

Other parameter selection

1 grind out the negative back edge of 0.05 ~ 0.1 mm, and enhance the strength of cutting edge.

2 rough car, the edge of the angle of =-3 degrees to -5 degrees, precision car edge dip angle of =-3 degrees to 0 degrees.

Note on the turning of titanium alloy

(1) the elastic modulus of titanium alloy, clamping the workpiece in the process of deformation and stress deformation, reduces the machining accuracy of workpiece installation; when the clamping force should not be too large, if necessary, can increase the auxiliary support.

(2) when machining cylindrical cutter can not be higher than the work center, to prevent the emergence of a dagger phenomenon.

(3) can not use the cutting fluid containing hydrogen. If the use of cutting fluid containing hydrogen, must take safety protection measures, at the same time after cutting parts should be thoroughly cleaned with cleaning agent does not contain chlorine in time.

(4) in the turning of thin-walled workpiece and machining tool, the main angle should not be too small.

(5) the titanium alloy parts cleaning, to prevent oil pollution or fingerprints, prevent corrosion caused by salt stress.

Considering the properties of titanium alloy turning, turning to the successful implementation of titanium alloy, the key is reasonable selection of tool materials; optimum tool geometry; low cutting speed, as far as possible to choose the larger cutting depth and feed rate, cooling liquid and filling full, will eventually achieve good machining results.