Aone Titanium Metal Materials
Why do we think titanium alloy is a difficult material to process? Because of the lack of a deep understanding of its processing mechanism and phenomena.
1. Physical phenomena of titanium processing
The cutting force of titanium alloy processing is only slightly higher than that of the
same hardness, but the physical phenomenon of processing titanium alloy is much more
complicated than that of processing steel, which makes the processing of titanium alloy
face great difficulties.
Most titanium alloys have very low thermal conductivity, only 1/7 of steel and 1/16 of
aluminum. Therefore, the heat generated during the cutting of the titanium alloy is not
quickly transferred to the workpiece or carried away by the chips, but accumulates in
the cutting area, and the generated temperature can be as high as 1000 ° C or more,
so that the cutting edge of the tool is rapidly worn, cracked and generated. Built-up
edge, the rapid appearance of worn edges, which in turn produces more heat in the
cutting area, further shortening the life of the tool.
Heat is the "culprit" of titanium alloys that are difficult to process!
2. Process for processing titanium alloy
Based on the understanding of the processing mechanism of titanium alloys and the previous
experience, the main processes for processing titanium alloys are as follows:
(1) A blade with a positive-angle geometry is used to reduce cutting force, heat of cutting,
and deformation of the workpiece.
(2) Maintain a constant feed to avoid hardening of the workpiece. The tool should always be
in the feed state during the cutting process. The radial ae amount during milling should be
30% of the radius.
(3) High-pressure and high-flow cutting fluid is used to ensure the thermal stability of the
process and prevent surface denaturation and tool damage caused by excessive temperature.
(4) Keep the blade edge sharp, the blunt tool is the cause of heat build-up and wear, which
is easy to cause tool failure.
(5) Processing in the softest state of the titanium alloy as much as possible, since the
material becomes harder to process after hardening, the heat treatment increases the strength
of the material and increases the wear of the blade.
(6) Use a large tool nose arc radius or chamfer cut-in to cut more blades into the cutting as
much as possible. This can reduce the cutting force and heat at every point and prevent local
damage. When milling titanium alloy, the cutting speed of each cutting parameter has the
greatest influence on the tool life, and the radial cutting amount (milling depth) is second.
3. Solve the problem of titanium processing from the blade
The blade groove wear that occurs during the processing of titanium alloys is the local wear
of the back and front in the direction of the cutting depth, which is often caused by the
hardened layer left by the previous processing. The chemical reaction and diffusion of the
tool and the workpiece material at a processing temperature exceeding 800 ° C is also one
of the causes of groove wear. Because during the processing, the titanium molecules of the
workpiece gather in the front area of the blade, and "weld" to the blade at high pressure
and high temperature to form a built-up edge. When the built-up edge is peeled off from
the blade, the cemented carbide coating of the blade is carried away, so titanium alloy
processing requires special blade materials and geometries.
4. Tool structure suitable for titanium machining
The focus of titanium machining is heat, and a large amount of high-pressure cutting fluid
must be sprayed onto the cutting edge in time to remove heat quickly. There is a unique
structure on the market for milling cutters specifically for titanium machining.
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