Titanium is one of the most widely used metals in industry, including a broad range of applications across the aerospace, military, biomedical, and automotive sectors. This material, considered to be one of the lightest in the periodic table, has a high strength-to-weight ratio and is extremely durable. Pure titanium is known for having the strength of 80,000 psi, while its alloys boast values in the range of 180,000 psi.
Compared to steel, titanium is twice as elastic, making it ideal for use in applications that warrant a flexible material resistant to cracking. Other desirable attributes of the metal include its resistance to oxidation and corrosion, non-toxicity, and recyclability.
However, titanium’s physical properties and chemical composition make it challenging to machine. Its high resistance to heat can damage tools and result in surface hardening if care is not taken during the milling process. Excessive temperatures reached can also result in titanium chips catching fire.
6 Tips to Ensure a Smooth Milling Process
1. Manage Temperatures
It is imperative that temperatures are kept low during the milling process as the energy generated during the procedure can strain and damage the cutting tool. The reduction of radial engagement results in higher cooling time for the cutting tool and maintenance of constant temperature at the point of cutting. By increasing the feed rate, heat generation is pushed into the titanium chip. Taking these preventative temperature management steps helps to extend the life of cutting tools.
2. Use a Larger Quantity of Flutes
Increasing the number of flutes utilized from the traditional number of five or six to about 10 leads to an increase in productivity.
3. Employ Climb Milling
In this process, known as a thick to thin approach, the titanium chip’s width decreases as milling continues; This ensures that heat is transferred to the chip and not the cutting tools. Climb milling produces a cleaner shear and puts chips behind the cutter so as to avoid obstruction during the cutting process.
4. Pay Attention to Surface Stability
Upon entry and exit into the titanium chip, tools are exposed to vibrating variations in force, reducing the lifespan of the instrument; Arcing into the chip can address this issue. The tool path arcs into the material in the same direction as the tool rotation, rather than through a straight line. The method of arcing in results in an increased cutting force that prevents damage to the tool. Ending your cut on a chamfer can produce a similar result to arcing in as the gradually sloped groove reduces strain.
5. Monitor Tools
Tools should be regularly checked for wear and tear as titanium is known to reduce tool quality over time. To maximize efficiency, tools should be sharp as dull tools tend to add additional heat, which increases wear.
6. Use Large Amounts of Coolant
Increasing the volume of coolant used reduces the probability of tool failure and irregularities in the material subsurface by better maintaining thermal stability. Coupling coolant increases with high-pressure pumps reduces chipping, which negatively affects the performance of the cutting tool.