CNC Knowledge: Why is “titanium alloy” so difficult to cut?

Titanium alloy has the advantages of small density, high resistance and corrosion resistance.

1

Classification of hard titanium alloy

At room temperature, there are three titanium alloy substrate tissues, and titanium alloy is also divided into three following categories: Titane alloy α (representing the TA3 brand number, etc.), β -titane alloy (representing the TB6 brand number, etc.) TC4, etc.).

Titanium alloy α

① Organization is an alpha-cristal phase fabric with six squares to anntial.

② The α titanium alloy is characterized by good high -temperature performance (long -term work can be worked at 500 ° C), a strong antioxidant capacity, but not thermal treatment and a strengthening, a low resistance to temperature temperature ambient.

③ Titanium α alloy is an easier treatment category in titanium alloy.

β titanium alloy

① The fabric is a single tissue β with a single cube network of body.

② The β titanium alloy is characterized by good plasticity on the cold deformation.

③ The cutting of the β titanium alloy is poor, and the typical plates include TB1, TB2, etc.

(α + β) titanium alloy

① With the tissue in phase α and β -two.

② It is characterized by a high normal temperature and high temperature intensity, good plasticity and tenacity, and can be improved by heat treatment, so it has a wide range of uses.

③ (A + β) The cut of titanium alloy is between the first two categories, and the typical brand is TCI and TC4.

2

The cause of titanium alloy is difficult to cut

Titanium alloy is widely used in various fields because of its excellent characteristics, but its “difficult cut” and its excellent characteristics are also “inseparable”.

① Flames of titanium crumbs:At high temperature (600 ° C), titanium shavings are easy to burn.

② Bad thermal conductivity:The thermal conductivity of the titanium alloy is small, only 1 / 6-1 / 7 of 45 steel.

③ Great kinship of chemistry:It is seriously linked to the hard alloy of TI, and the coatings of many tools contain Ti.

④ Small elastic module:About 1/2 of the elastic module of 45 steel, so elastic recovery is large. At the same time, the part is also subject to folding deformation.

⑤ The cold and hard phenomenon is serious:The chemical activity of the titanium is large. The cold and hard phenomenon will not only reduce the resistance to fatigue of parts, but will also exacerbate the wear of the tool.

⑥ Short length contact length:Under the action of oxygen and nitrogen in the air, titanium alloy will form a hard and crunchy compound, so that the shavings in short fragments, so that the length of the contact of the package of knife is very short, the cutting force and the cutting heat are concentrated near the slice and the knife tools are concentrated.

3

Specific measurements to cut the titanium alloy

If you want to overcome the titanium alloy, you only know that the reason why this is not enough, and you should apply the right medication according to its characteristics.

Selection of tool materials:Use the hard alloy of the YG class (ISO K) without TI, such as diamond and boron nitride tools. Currently, various tool providers have their own titanium alloy cutting tools, and readers can choose according to each album example.

Selection of the geometric parameters of the tool:The entrance angle and the main corner of the knife must be smaller and the top arc of the appropriate knife must be crushed and the rear angle must be large. Generally hard alloy car knife

C。 = 5 ° 〜8 ° A。 = 10 ° ~ 15 °,

λ。 = -3 ° ~ -5 ° Kr = 45 ° ~ 75 °

Re = 0.5 to 1.0 mm

In addition, the roughness values ​​of the front and rear of the tool should be small, generally RA ≤ 02 μm.

Selection of the cutting dose:Choose a lower cut speed, a large power supply and a volume of dining knife. During the cut with a hard alloy knife car, the amount of knife must be 1 to 3 mm and the amount of knife with a rough car should be greater than the depth of the oxidation skin, and the quantity of ‘power supply is 0.1 to 0.3 mm / r. The selection of the cutting speed must be determined as a function of the resistance of the Titane Treatment alloy and the maximum size of the carrier.

Cooling lubrication:Generally, the fluid of emulsification of the polar pressure should be used to cool and the flow must be sufficient. However, if the intensity of the part of the parts is high, the sulfur and the chlorine should not be contained in the cutting fluid. If a cutting liquid containing chlorine is used, hydrogen will be released during the high temperature cutting process, which is absorbed by titanium, causing hydrogen and porridge: it can also cause corrosion and cracking High temperature constraint of high temperature alloy.

The part of the part:The tightening force should not be too large, in order to avoid deformation of the part.

Others: the machine must have good rigidity.