CNC Machining Titanium: Alloys and Tips for a Tough Metal

by | Oct 18, 2021 | CNC Machining, Machining Materials

Are you considering titanium to be the base material for your next design? Or perhaps you’ve heard about the difficulties of machining Titanium parts and are unsure of which titanium grades can be used in CNC machining? If you answered yes to any of these questions, you came to the right place.

Titanium is a magnificent material, and due to its exceptional properties and high biocompatibility, it is widely used in the aerospace and biomedical industries. However, in the same way that its physical properties make titanium great, they also affect the CNC machining process. In comparison to the other materials and metals, titanium requires a well-planned and dedicated manufacturing procedure.

This article will help you understand the process of machining titanium, including understanding the properties of this metal, some of the titanium grades you should consider, and even some tips about handling it.

Considerations for Machining Titanium Parts

Titanium chemical element symbol

Titanium has gained popularity in recent years because of its valuable ability to make lightweight, high strength, and highly corrosion-resistant products. Parts crafted from titanium tend to last longer while keeping a better performance than other materials. Plus, titanium is nontoxic.

However, titanium is also not perfect. It is a poor thermal conductor, and when its surface does not receive adequate treatment, it can be easily damaged. In addition, the machining process usually leaves behind chatter marks.

All of this contributes to the poor machinability of titanium. Still, luckily machinists worldwide have studied the properties of titanium relative to other metals and found ways to improve the manufacturing process.

For example, machining titanium requires a cautious heat dissipation strategy. To address this, CNC machining experts have established that increasing the number of flutes in the cutting tool is effective when machining titanium parts. Four to six flutes are used for other metals, but titanium often requires ten or even more.

Additionally, to address titanium’s high strength and poor cooling, machinists use special titanium aluminum nitride (TiAlN) or titanium carbo-nitride (TiCN) coated tooling.

In summary, experts advise that the fundamental key for machining titanium is patience. To keep heat accumulation under control, reduce the chatter at surface termination, avoid damage to the piece, and keep the machining process safe, it is suggested to slow down to a safe speed.

The Top 10 Most Common Titanium Grades for CNC Machining

Due to the increasing demand for titanium, several machinable grades have been developed in the industry. They are differentiated based on the content of pure titanium and other elements they contain, such as oxygen, palladium, nickel, or molybdenum.

With different alloying elements come different mechanical properties for each titanium grade, meaning you can pick just the right titanium grade for your application. Check out the following table to discover more and understand more about titanium machinability!

Table 1

Alloy/Grade Description Advantages Disadvantages Applications
Grade 1
Commercially pure titanium with low oxygen content.
One of the most commonly used grades of titanium. It is the most ductile and the softest titanium alloy. Excellent relative formability and machinability, corrosion resistance, and impact toughness. Lower strength compared to the other titanium grades. Chemical processing, desalination, medical industry, automotive parts, airframe structure.
Grade 2
Commercially pure titanium with standard oxygen content.
Pure titanium, known as the workhorse of the titanium industry. High corrosion resistance, good weldability, strength, ductility, and formability. High relative machinability. Not as strong as other titanium grades, but stronger than grade 1 Aircraft engines, hydrocarbon processing, chlorate manufacturing, medical industry.
Grade 3
Commercially pure titanium with medium oxygen content.
Grade 3 is the least commercially used, but it possesses good mechanical properties. High strength and corrosion resistance. Good relative machinability. Less formability than grades 1 and 2. Medical industry, marine industry, aerospace structures.
Grade 4
Commercially pure titanium with high oxygen content.
Known as the strongest of the four commercially pure grades. Very high strength and corrosion resistance. Okay relative machinability. Hard to machine, requires slow speeds, high coolant flow, and high feed rates. Cryogenic vessels, heat exchangers, CPI equipment, surgical hardware, airframe components.
Grade 5
Titanium alloy – Ti6Al4V
This is the most commonly used alloy of titanium. It contains 6% aluminum and 4% of vanadium. High corrosion resistance and high formability. Poor relative machinability. Less strong than the other alloys. Critical airframe structures, power generation, marine & offshore applications.
Grade 6
Titanium alloy – Ti5Al-2.5Sn
The most commonly used for airframe and jet engine applications. Good weldability, stability, and strength at elevated temperatures. Intermediate strength for titanium alloy standards. Airframe & jet engine applications, liquid gas & propellant containment for rockets and space vehicles.
Grade 7
Titanium alloy, sometimes considered “pure”  – Ti-0.15Pd
Similar to grade 2, but this one contains small quantities of palladium, enhancing corrosion resistance. Extremely good corrosion resistance, excellent weldability, and formability. Not as strong as other titanium alloys. Chemical processing & production equipment components.
Grade 11
Titanium alloy, sometimes considered “pure”  – Ti-0.15Pd
Similar to Grade 7, but with a lower tolerance for other impurities. Excellent corrosion resistance, optimum ductility, and formability. Even lower strength relative to grade 7. Marine applications, chlorate manufacturing, desalination.
Grade 12
Titanium alloy – Ti0.3Mo0.8Ni
This highly durable alloy contains 0.3% of molybdenum and 0.8% of nickel. Great weldability, excellent strength at high temperatures, excellent corrosion resistance. It costs more than the other alloys. Shell and heat exchangers, hydrometallurgical applications, aircraft  & marine components.
Grade 23
Titanium alloy – T6Al4V-ELI
Also known as TAV-EIL in the market, which stands for Extra Low Interstitial. It is similar to Grade 5 but with higher purity. Great ductility and formability, good fracture toughness. Optimum biocompatibility. Poor relative machinability. Has a lower strength than the other Titanium Alloys. Orthopedic pins & screws, orthopedic cables, surgical staples, orthodontic appliances.

 

Choosing and Working with the Right Grade of Titanium

As you may have noticed, choosing the most suitable titanium for your product depends on the properties and applications you want. If you are trying to develop products for medical applications, you may want to choose the grade 23 titanium. Alternatively, if you are looking for a piece with excellent performance at elevated temperatures, you may want to work with the grade 6 titanium.

Just remember that titanium alloys require careful machining, which must be carried out by trained experts. In contrast to free machining metals like Brass C360 or Steel SS416, working with titanium requires expertise, patience, and the correct tools.

If you want to find an expert to help you with your titanium piece, look no further than the experts available to help provide you with CNC machining services.

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