Titanium CNC Machining: 2024 Things to Consider
By Lucas Lo | Updated: August 03, 2024
Table of Contents
Titanium CNC machining is a specialized process that offers a range of benefits for industries requiring precision and durability. Titanium’s unique properties make it a preferred material in the aerospace, medical, and automotive industries. This article delves into the specifics of why titanium is used, its advantages, and the benefits of CNC machining titanium.
What is Titanium?
Titanium is a chemical element with the symbol Ti and atomic number 22. Known for its high strength-to-weight ratio, excellent corrosion resistance, and ability to withstand extreme temperatures, titanium is a versatile material used in various high-performance applications. It is approximately 60% denser than aluminum but twice as strong, making it an ideal choice for applications where both weight and strength are critical factors.
Why Use Titanium?
Titanium offers several advantages that make it a superior material for various applications:
High Strength-to-Weight Ratio: Titanium’s density is 4.5 grams per cubic centimeter, which is significantly lower than steel but with comparable strength. This property makes it ideal for aerospace and automotive applications where reducing weight can enhance performance and fuel efficiency.
Corrosion Resistance: Titanium is highly resistant to corrosion in a wide range of environments, including seawater, chlorine, and acids. This makes it suitable for chemical processing, marine, and biomedical applications.
Biocompatibility: Titanium is biocompatible, meaning it is not harmful or toxic to living tissue. This property makes it the material of choice for medical implants and devices, such as hip replacements and dental implants.
Thermal Stability: Titanium can withstand extreme temperatures without losing its mechanical properties. This makes it ideal for use in high-temperature environments, such as jet engines and power generation plants.
Low Thermal Expansion: Titanium’s low thermal expansion coefficient ensures dimensional stability under temperature fluctuations, crucial for precision components in various industries.
Why CNC Machine Titanium?
CNC (computer numerical control) machining is ideal for titanium machining due to its high precision, high efficiency, and ability to handle challenging properties of the material. Titanium is widely used in high-performance and racing exhaust systems due to its excellent strength-to-weight ratio and corrosion resistance. Titanium exhaust systems are typically 30% to 50% lighter than stainless steel exhaust systems, which can significantly reduce the overall weight of the vehicle, thereby improving acceleration performance, fuel efficiency, and handling.
CNC machines can achieve extremely tight tolerances, which is critical for complex and high-precision titanium parts. This precision ensures that parts meet strict specifications, reducing the need for post-processing.
Machining titanium alloys using traditional methods is very time-consuming, and CNC machines run continuously with minimal human intervention, improving production efficiency and shortening delivery time.
In addition, titanium materials are expensive compared to other materials, and using CNC machining can reduce material waste.
For some industries, CNC machining can complete the repeatability and complex shapes required. Moreover, titanium alloys have high requirements for cutting tools. Advanced CNC machines have tool monitoring and management systems to extend tool life and maintain processing quality.
Different Titanium Grades for CNC Machining
There are several grades of titanium, each with unique properties that make it suitable for a variety of applications. Understanding these grades can help you choose the right titanium for a specific CNC machining project.
Grade 1 Titanium
Grade 1 titanium is the softest and most ductile of all titanium grades. It has excellent corrosion resistance and formability. This grade is well suited for chemical processing plants, marine environments, and medical applications where high corrosion resistance is critical.
Grade 2 Titanium
Grade 2 is the most widely used grade of titanium. It balances strength, ductility, and weldability with good corrosion resistance. This titanium grade is commonly used in aerospace, automotive, and construction applications, and is also used in medical implants and industrial components.
Grade 5 Titanium (Ti-6Al-4V)
Grade 5, also known as Ti-6Al-4V, is the most commonly used alloy titanium. It combines high strength, light weight, and excellent corrosion resistance. It can be heat treated, which further enhances its strength. This grade is common in aerospace components, high-performance automotive parts, medical devices, and sports equipment.
Grade 7 Titanium
Grade 7 is similar to Grade 2 but contains a small amount of palladium, which enhances its corrosion resistance, especially in reducing and acidic environments. It is used in chemical processing, power generation, and marine applications where extreme corrosion resistance is required.
Grade 9 Titanium (Ti-3Al-2.5V)
Combining strength and formability, it offers improved weldability and increased corrosion resistance compared to Grade 5.
It is commonly used in aerospace piping, sports equipment, and marine environments for applications that require high strength and lightweight.
Choosing the right titanium grade for CNC machining depends on the specific requirements of the application. Each grade has a unique set of properties that ensure the right titanium choice for a variety of industrial, medical, and high-performance uses. By understanding these grades, manufacturers can optimize their CNC machining processes to produce high-quality, durable, and efficient components.
Things to Consider When Machining Titanium
Heat Buildup
Titanium alloys have a low thermal conductivity, which means that heat generated during machining is not dissipated quickly. Excessive heat can cause rapid tool wear, shorten tool life, and increase costs. And prolonged exposure to heat can cause workpiece deformation and affect dimensional accuracy.
High-pressure coolant systems effectively manage and dissipate heat during machining. In addition, using lower cutting speeds and higher feed rates can help reduce heat buildup.
Wear
Wear is a form of wear caused by adhesion between sliding surfaces, which is often a problem when machining titanium alloys due to their reactive nature. Unwanted tool marks can be left on the workpiece and can also affect the surface finish.
Use sharp, high-quality cutting tools and apply appropriate lubricants. Coated tools, such as those with TiN or TiAlN coatings, can reduce the tendency of titanium alloys to wear.
Workholding
Because of the high forces generated during titanium machining, improper workholding can cause vibrations that affect surface finish and tool life. Using sturdy fixtures and clamps to hold the workpiece and vibration-absorbing materials, techniques can also help stabilize the setup.
Feed and Speed
When machining titanium, optimal feed rates and spindle speeds are crucial for efficiency and tool longevity. Feed rates for titanium should be around 1/3 to 1/2 of those used for steel. Slower feeds help decrease cutting forces and heat generation. High spindle speeds are more effective for milling titanium, typically around 3000 to 5000 RPM. These speeds help achieve a better surface finish and reduce cycle times.
Cost of Titanium Machining
Machining titanium can be costly due to the material’s challenging properties. For example, a test showed a titanium removal rate of 20 cubic inches per minute, equating to 1200 cubic inches per hour, with tools having a lifespan of approximately three hours. The cost of machining titanium was calculated at $0.0375 per cubic inch of metal removed, including the cost of tool inserts.
Surface Feet per Minute (SFM) for Titanium
The appropriate cutting speed for titanium varies depending on the specific alloy. Unalloyed titanium can be machined at speeds up to 180 SFM, while tougher beta alloys require speeds as low as 30 SFM due to their toughness. Generally, the more vanadium and chromium in the alloy, the lower the cutting speed needed, as these elements increase the alloy’s hardness and toughness, making it more challenging to machine.
How to Choose the Right Cutting Tools for Machining Titanium？
Titanium machining presents unique challenges, such as heat buildup, wear, and workholding issues. Choosing the right cutting tool is essential for efficient titanium machining. You need to consider tool material, tool coating, tool geometry, and cutting parameters.
- Carbide tools: Provide the hardness required to cut titanium and resist wear.
- High-speed steel (HSS): Suitable for less aggressive machining, but may wear faster than carbide tools.
- TiAlN coating: Titanium aluminum nitride (TiAlN) coatings offer excellent heat resistance and reduce friction.
- TiN coating: Titanium nitride (TiN) coatings help reduce tool wear and galling.
- Positive rake angle: Reduces cutting forces and heat generation.
- Sharp edge: Essential for reducing galling and improving surface finish.
- Cutting speed: Use lower cutting speeds to minimize heat buildup.
- Feed rate: Higher feed rates reduce heat and extend tool life.
- Depth of cut: Shallower depths of cut help maintain tool life and reduce stress on the workpiece.
Conclusion
Titanium machining offers significant advantages in strength, weight and corrosion resistance. However, it also presents unique challenges such as heat build-up, wear and the need for robust workholding solutions.
In addition, a variety of surface treatments can enhance the functionality and appearance of titanium parts to meet the various needs of industries such as aerospace, medical, automotive, and consumer goods.
By leveraging the advantages of CNC machining and applying the appropriate technology and surface treatments, manufacturers can produce high-quality titanium parts that meet strict industry standards and provide excellent performance.
Please choose us Ecoreprap, we provide professional titanium alloy CNC machining surface treatment as well as CNC machining technology. Please contact us for a quote (all uploads are secure and confidential).
Lucas is a technical writer at ECOREPRAP. He has eight years of CNC programming and operating experience, including five-axis programming. He also spent three years in CNC engineering, quoting, design, and project management. Lucas holds an associate degree in mold design and has self-taught knowledge in materials science. He’s a lifelong learner who loves sharing his expertise.
