Of course, Titanium, a rigid material, is difficult to machine. The difficulties include tool wear as well as high cutting forces. The properties of the material include:
- Its low thermal conductivity.
- Low thermal expansion.
- High corrosion resistance.
- High strength-to-weight ratio.
But, CNC titanium machining is easy.
Some people think titanium is really hard to machine. The challenges are not so much with the cutting process as chip removal and keeping the cutting tool cool. The chips should be very fine, almost powder-like, and they tend to bind together. This requires excellent chip removal and coolant. If the chips are allowed to build upon the cutting tool, the tool may overheat and dull.
The cutting tool is also the biggest problem in CNC titanium machining. The hardness of titanium is 66-68 Rockwell C, which is harder than most tool steels, and carbide tooling does not work well. The machinability of titanium can be improved by cryogenically treating the cutting tools. Some manufacturers offer cryogenically treated cutting tools, which will enhance the production schedule.
The machining of titanium alloys consists of six basic steps:
1. Select the correct cutter.
Three types of cutters may be used: solid, indexable, and brazed. Solid cutters are made from high-speed steel and are indexable. Indexable tools are made from super high-speed steel and brazed, and they may be either solid or brazed.
The selection of a cutter depends on the volume of material to be removed. When removing large amounts of material, will use solid blades. Indexable cutters are used when removing small amounts of material. When both conditions exist, a combination of solid and indexable cutters may be used.
2. Select a tool holder that will accommodate the cutter.
Tool holders should accommodate the tool that will be used to machine the part. The holder should have enough shank length to allow proper seating of the cutter.
3. Set spindle speed and feed.
Set the spindle speed set is based on the type of cutter used, and the feed rate chosen is based on the type of machining material.
4. Select a cutting fluid.
Cutting fluid should be used on all titanium alloys chlorine-containing.
5. Set up the CNC unit.
The CNC unit should be appropriately calibrated. The CNC unit should have the RPMs set adequately.
6. Set up the CNC program.
The CNC program should be written appropriately. The CNC program should check the machine code and tool compensations.