Processability of Titanium Alloy and Technology of Grinding and Polishing

Many process parameters of titanium alloys in forging, volume stamping and sheet stamping are close to those in steel processing. But there are some important features that must be paid attention to when pressing working titanium and titanium alloys. When the titanium alloy is cold plastically deformed, regardless of its chemical composition and mechanical properties, the strength will be greatly improved, and the plasticity will be correspondingly reduced. For this reason, annealing treatment between processes must be performed. The low thermal conductivity of titanium and the formation of non-coiled shavings are the reasons for the important characteristics of the machining of titanium and its alloys. When cutting titanium, the tool face will generate high temperature. In order to dissipate the heat, sharpened knives can be used, and a large amount of coolant and lubricant can be supplied. The tools made of carbide BK6M, BK8, BK4, BK2 have good cutting performance in grinding, milling and drilling.

The grinding and polishing of titanium alloys are divided into the following three methods:

(1) Fine grinding

That is to use conventional various emery rubber wheels to grind the surface of titanium and titanium alloy castings. The problem that needs to be paid attention to during grinding is still not to make the casting generate heat, not to cause grinding damage on the surface of the casting, and to make the entire surface smooth and smooth.

(2) Barrel grinding method

The so-called barrel grinding method is to put the processed castings, abrasives, water and additives into the barrel-type grinding tank, and the grinding barrels rotate and vibrate, so that friction is generated between the mixture of abrasives and the processed castings, and the surface of the castings is ground. Smooth and flat. It is characterized by no dust pollution, low labor intensity, and no heat generation in the conventional grinding process. At present, Japan has commercialized barrel grinders and abrasives for grinding Grade 1 Titanium Bar, other metal castings and plastics. It has been confirmed by experiments that the grinding efficiency of pk series abrasives is high, but the surface roughness is also very high. Although the grinding efficiency of SA and B series abrasives is not as good as that of PK, the surface smoothness of the ground titanium castings is higher. At present, the Fourth Military Medical University has successfully developed the first domestic dental barrel grinder.

(3) Mechanical polishing method

The method of polishing the surface of titanium and titanium-containing alloys using soft cloths or black brushes of different specifications, dipped in special polishing pastes for titanium and titanium-containing alloys. When polishing titanium castings, it is necessary to completely clear the contamination layer on the surface of the casting and no new grinding and hardening layer, which will not achieve the ideal polishing effect. When polishing, high speed and light pressure should be used for polishing. The author has also tested the use of green polishing paste to polish titanium and titanium-containing alloy castings, and achieved a relatively ideal polishing effect. Polished titanium and titanium-containing titanium alloy castings cannot be washed with water immediately. The surface oxide film must be completely formed before washing with water, otherwise the surface will be darkened.