Machining Titanium

Titanium was once a material that was used by only a few select shops and was rarely touched by the average machinist, but now it is used much more frequently and has been used by many machinists over the course of their careers. The machining of titanium is not similar to that of standard materials such as aluminum and steel in the industry. However, because of their enormous profits, more shops are beginning to express an interest in these jobs.

In this article, we will cover successful practices for cnc machining titanium, how to select the appropriate cutting tools, and things that need to be considered by machinists. wanto know more about other machining process, please go to Manufacturer of Turned Components page.

Machining Titanium: Key Considerations

CNC Machining with titanium is a complex process because of its strength, making it appropriate for most demanding applications while simultaneously being difficult to machine. It is vital to comprehend the details of the machining process to get the best outcome and extend the tool’s lifespan.

1. Selection of Cutting Tools

Machining titanium requires considering cutting tools. Since titanium is resistant to heat and hard, it is crucial to choose tools that can withstand these properties. Coated high-speed steel tools with tungsten, carbon, and vanadium are suitable because of their hardness retention at temperatures up to 600°C. These tools allow for better cutting and reduce the chances of chipped edges, improving the machining processes.

2. Importance of Tool Coatings

The coating of cutting tools is significant, and applying the correct type of coating will improve the cutting tools’ performance during titanium machining. Coatings such as titanium aluminum nitride (TiAlN) reduce heat generation by creating a layer of aluminum oxide on the tool’s surface. This layer minimizes heat conduction and chemical interaction between the tool and workpiece, increasing tool life and chip removal.

3. Ensuring Stability in Machining

Stability during titanium machining is vital to reduce vibration and increase the accuracy of the cutting. Due to the flexibility of titanium and high forces, chattering is likely to occur, which is detrimental to the quality of the machined surface. Work with more giant core-diameter end mills to improve stability and ensure the shortest distance between the spindle nose and the tooltip. Using constant machining feeds and speeds also reduces heat and strain hardening on the tool, thus maintaining the tool’s functionality and durability.

4. Advantages of Climb Milling

Climb milling has several benefits when used in custom titanium machining. In climb milling, the chip thickness starts from a wider one and gradually reduces, while in down milling, the opposite is true. This helps enhance the heat transfer to the chips rather than the workpiece, thus minimizing thermal stress and tool wear. Climb milling enhances shear and proper chip clearing behind the cutter, improving machining and surface finish efficiency.

Knowledge of these strategies is crucial to the successful machining of titanium. Thus, selecting proper tools, appropriate coatings, stability, and adequate milling strategy will enable the machinists to obtain the desired dimensions and efficiency of the titanium components under the industrial requirements.

Common Grades Used For CNC Machining

Let’s discuss some common grades typically used in cnc titanium machining.

Grade 1: Commercially pure titanium containing not more than 0.3% of Oxygen.

Some of the most common types include grade 1 titanium with high ductility and low oxygen content. It has good machinability, high impact toughness, and high corrosion resistance and is applied in the medical, automobile, and aerospace industries. However, Grade 1 titanium has some drawbacks; it has lower strength than the other grades of titanium and thus cannot be used in areas where stress is applied.

Grade 2 (Commercially Pure Titanium containing a standard amount of Oxygen)

The second grade of titanium is also known as the workhorse titanium because of its average oxygen content, high corrosion resistance, formability, weldability, and ductility. It is widely used in the medical and aerospace industries, especially in aircraft engine parts, due to its mechanical characteristics that enable it to withstand the applied conditions.

Grade 3(Pure titanium with a moderate quantity of oxygen)

Grade 3 titanium is considered to have moderate mechanical properties such as corrosion, workability, and strength. It is not as commonly used in commercial applications as Grade 1 and 2. Still, it is used in medical, marine, and aerospace industries where consistent performance of parts and assemblies is required.

Grade 4 (Pure Titanium with high oxygen content)

Grade 4 titanium is one of the most powerful and chemically stable materials for cnc titanium machining. it is appreciated for its ability to work in harsh environments. Nonetheless, it has a high oxygen content, which makes it rather difficult to machine. It uses a lot of coolant and has high feed rates during machining. This grade is used in cryogenic vessels, chemical processing equipment, and airframe parts where high strength and toughness are essential.

Grade 5 (Ti6Al4V)

Ti6Al4V is an alpha-beta titanium alloy with 6% Al and 4% V; this material has good mechanical properties, including high strength, reasonable formability, and good corrosion resistance. It is used in power plants, offshore platforms, ships and ship parts, high-strength aerospace products, and so on.  The grade 5 titanium is applied in all the areas where high performance is needed in various conditions of the environment.

Grade 6 (Ti 5Al-2.5Sn)

Grade 6 titanium alloy has good stability and high strength and can quickly be joined, especially at high operating temperatures. This makes it ideal for use in airframes, jet engines, and other aerospace parts and components where the strength of the material is of utmost consideration. Due to its ability to handle high temperatures and stress conditions, it is suitable for rigorous conditions.

Grade 7 (Ti-0.15Pd)

When comparing Grade 2 with Grade 7, the latter contains palladium to improve the corrosion properties, particularly in chemical applications. It has good forming and welding characteristics, and because of its resistance to corrosive agents, it is extensively used in chemical processing equipment where strength and durability are essential.

Grade 11 (Ti-0.15Pd)

Similarly to the previous Grade 7 titanium, the Grade 11 titanium alloy has higher ductility and lower impurity acceptance. It is used in marine applications and chlorate manufacturing because of its non-corrosive nature and compatibility with salt water. Grade 11 titanium is less potent than Grade 7 titanium, and therefore, it is used where flexibility and corrosion resistance are needed.

Grade 12 (Ti 0.3 Mo 0.8 Ni)

Grade 12 titanium alloy contains molybdenum and nickel and is weldable; has high strength at high temperatures and good corrosion resistance. It is used in shell and heat exchangers, marine parts, aircraft parts, and other industries because of its mechanical strength, which enables it to withstand the environment.

Grade 23 (Ti6Al4V-ELI)

Extra low interstitial titanium or Grade 23 titanium is not precisely like Grade 5 and has better biocompatibility and fracture toughness than Grade 5. Because of its high purity, it can be used in medical applications such as orthopaedic implants, surgical staples and orthodontic appliances where compatibility with body tissues and strength is paramount.

Advantages of Choosing Titanium for CNC Machining Parts

Out of all these materials, titanium can be singled out in CNC machining due to the peculiarities that make it suitable for specific industries. Its improved biocompatibility makes it very important in medicine because it ensures that implants will not be expelled from the body. This quality is high corrosion resistance, making valuable titanium in marine and chemical processing industries where the material’s ability to last long is paramount.

Another property of Titanium is its high strength-to-weight ratio, which is very useful in aerospace and automotive industries where the reduction of weight while increasing strength is significant in enhancing the performance and efficiency of the equipment. Its high ductility allows for complex geometries and complex profiles required for specific uses in various industries. However, titanium is easy to machine, so the parts can be produced with great precision and high reliability to achieve the desired tolerance levels.

Challenges in Machining Titanium

It is not easy to work with titanium alloys because the following challenges will likely be met when machining the material. It has high chemical reactivity and galling that leads to the formation of surface defects such as oxidation and embrittlement during the machining process, which compromises the quality and reliability of the component.

The control of temperature rise and forces is crucial because titanium has low thermal conductivity; heat builds up in the cutting zone, which leads to rapid tool wear and may influence the surface finish. Furthermore, it has residual and hardening stresses** after the machining operation, and these stresses cause dimensional instability and, at times, the part fails.

Valuable Tips for Efficient Titanium Machining

However, some critical factors must be controlled to optimize titanium machining since it is not easy. Clamping of workpieces helps minimize vibrations and tool chatter and therefore enhances the accuracy and surface finish of the workpieces. Using highly preloaded tooling and short-cutting tools reduces the amount of deflection, and thus accuracy is achieved even on a problematic part.

Selecting specific cutting tools for titanium with better coatings like TiCN or TiAlN improves wear resistance. It increases the tools’ durability and the process’s efficiency and cost. Thus, it is necessary to control the state of the tools and, if required, replace them with new ones to maintain the high quality of the machined parts and not to increase the tool wear rate during long production.

Controlling the cutting parameters, such as feed rates, spindle speeds, and chip loads, is vital to minimize heat generation and tool wear. The application of adequate coolant supply at the cutting zone helps in the flow of chips and maintains lower cutting temperatures, thus reducing the failure of tools and surface roughness.

Optimizing the cutting parameters, such as the axial depth of cut and the radial depth of cut, increases the material removal rate and reduces the cutting forces and heat generation, making the machining of titanium a reliable process. So, it could be said that machining titanium is not an easy task. Still, because of its specific properties and correct machining methods, it is ineluctable in industries requiring high strength, high temperature, and highly reliable CNC machined parts.

Distinctions in Machining Titanium To Other Materials

In the metals category, titanium has one of the most remarkable characteristics: its strength. Therefore, all those industries that require high-stress elements and parts must be used in harsh conditions. This makes it even more desirable in different sectors due to its high heat and corrosion resistance.

Strength and Durability

Compared to other metals, titanium has higher tensile strength and is used in applications where high strength at high temperatures is required. While steel can be categorized according to alloying elements, and its characteristics can significantly differ from the primary material, titanium can be used in its pure form or as an alloy, the most popular of which is Grade 5 (Ti 6Al-4V), which accounts for 50% of the titanium consumption in the world.

Cost Considerations

Nonetheless, titanium has its major disadvantage – the cost is still considerably higher than other materials such as steel or aluminum. These materials are commonly used by engineers and manufacturers, where the cost factor becomes very important, and the application does not require the higher quality of the material. For example, steel has weldability, strength, and corrosion resistance, which makes it ideal for use in structures and the home.

Comparison with Steel

Stainless steel and other steel alloys are prized for their ability to be welded, strength, and variety of uses in everything from household items to construction. However, stainless steel is heavier than titanium. Thus, as with strong and light titanium, it cannot be used where weight is a significant consideration.

Comparison with Aluminum

Aluminum is similar to titanium in that it offers a high strength-to-weight ratio and is highly resistant to corrosion, although not as expensive. It is preferred in cases where extensive work is to be done at a lower cost and where structure fabrication is easy. Aluminum is more electrically and thermally conductive than most other metals. Therefore, it can be used in heat and electricity transfer applications but is not as strong or heat resistant as titanium.

Corrosion Resistance

It is noteworthy that titanium has very high corrosion resistance among all known metals, and its use is preferred where this characteristic is crucial. Titanium, when exposed to air, develops an oxide layer that increases its durability and resistance to corrosive atmospheres. This self-repairing feature makes titanium very suitable for use in situations that need long-term use and little or no maintenance.

Applications of Titanium Machined Parts

Titanium machined parts are preferred since they are durable, anti-corrosive and have a nice appearance. These properties make them suitable for use in many industries and fields.

Marine/Naval Industry

Titanium is one of the most resistant materials to corrosion, and hence, it is very suitable for use in the marine industry. Some application areas are propeller shafts, underwater robotics, rigging equipment, ball valves, marine heat exchangers, fire system piping, pumps, exhaust stack liners, and onboard cooling systems. This makes it possible to have durability and efficiency of several marine parts and accessories.

Aerospace:

In the aerospace industry, titanium is highly valued for its high strength-to-weight ratio, excellent corrosion resistance, and ability to withstand extreme temperatures. These attributes make it suitable for critical aerospace parts, including seats, turbines, shafts, valves, casings, filter parts, and oxygen generation. In these applications, it is possible to note the use of titanium material that offers the benefits of low density, high strength, and acceptable performance under high stress.

Automotive:

While aluminum is often favored in the automotive industry due to its availability and cost-effectiveness, titanium still plays a significant role in producing high-performance automotive parts. In internal combustion engines, valves, valve springs, retainers, car stop brackets, hanging ear nuts, engine piston pins, suspension springs, brake calliper pistons, engine rockers, and connecting rods are manufactured from titanium and its alloys. Titanium in these parts enhances the efficiency and durability of automobiles and thus is incorporated into the manufacturing process.

Medical and Dental:

The medical and dental industries rely on titanium for its excellent corrosion resistance, low electrical conductivity, and compatibility with physiological pH levels. Titanium is applied in the fabrication of a variety of medical devices and implants, including tapered, straight or self-tapping bone screws for orthopaedic and dental applications, cranial screws for cranial fixation systems, spinal fixation rods, connectors and plates, and orthopaedic pins. Titanium is used in these vital functions due to its compatibility with the human body and strength, which ensures the patient’s safety and the equipment’s longevity.

In Conclusion

From the above observations, it can be concluded that even though titanium is a material that is not easy to machine, the problems associated with it can be overcome using proper tools and techniques. CNM offers consultancy and services in machining magnesium, titanium machining so that your operations are practical and efficient. Select CNM for your reliable China titanium machining partner in mastering the peculiarities of titanium machining and increasing the results of your work.