CNC Machining Titanium: All You Need to Know

Titanium is an excellent machining material with a wide variety of properties, favored for CNC machining due to its excellent corrosion resistance, heat resistance, durability, and good biocompatibility for a wide range of aerospace aviation and medical applications. This article discusses important knowledge about machining titanium, including how to choose tools, why titanium is difficult to machine, tips for CNC machining titanium, and applications.

What is Titanium?

Titanium is a transition metal with a silvery-white luster that was discovered in England in 1791. Two of the most important characteristics of titanium are its strength-to-weight ratio and its resistance to corrosion. In addition, it has excellent biocompatibility and is harmless even when used in large quantities, making it valuable in the medical field. In manufacturing, titanium is often alloyed with aluminum, vanadium, zirconium and molybdenum.

Why Choose Titanium for CNC Machining Parts?

Although titanium is expensive to machine, it remains a popular manufacturing material. The following are the main advantages of titanium as a machining material:

Corrosion Resistance: Titanium reacts readily with oxygen to form a thin oxide layer on its surface, resulting in natural corrosion resistance.

Strength-to-weight Ratio: Titanium's density is 4.51g/cm3, 57% of steel, making it less dense; titanium is less than twice as heavy as aluminum and three times stronger.

Biocompatibility: Titanium has high biocompatibility. In the human body, it can resist corrosion from secretions and is non-toxic, making it an ideal material for the medical industry.

Durability: Titanium has very high strength, the specific strength of titanium alloy is 3.5 times that of stainless steel, 1.3 times that of aluminum alloy and 1.7 times that of magnesium alloy.

Non-magnetic: titanium is non-magnetic, will not be affected by magnetic interference, is a medical scanner, aircraft, satellite, radar important materials.

Why CNC Machining Titanium?

Due to the characteristics of titanium alloy such as high strength and low thermal conductivity, there are problems such as difficult cutting and machining, low machining efficiency, and serious tool wear, so the production cost is high. However, with the continuous improvement of CNC cutting grinding molding processing technology, the cost continues to decline, CNC machining process is mature and high precision, is still the current mainstream processing of titanium alloy.

Why is Titanium Hard to Machine?

Temperature Concentration

The thermal conductivity of most titanium alloys is very low, only 1/7 of steel, 1/16 of aluminum, and 1/25 of copper. Therefore, the heat generated during cutting of titanium alloys is not quickly transferred to the workpiece or carried away by the chips, but is concentrated in the cutting area.

The temperature generated at the tip of the tool can be as high as 1,000°C, resulting in rapid wear and cracking of the cutting edge of the tool and chip accumulation, shortening the tool life tool.

Elastic Deformation

The modulus of elasticity of titanium alloy is not very high, for example, the modulus of elasticity of Ti-6Al-4V (grade 5 titanium) is only 110 Gpa, while the modulus of elasticity of 45 steel is 210 Gpa, and the elastic modulus of stainless steel such as 304 and 316 is also around 200 Gpa. Therefore, elastic deformation is easy to occur when machining titanium alloy.

Vibration

The elasticity of titanium alloys may be beneficial to the performance of the part, but the elastic deformation of the workpiece during the cutting process is a significant cause of vibration.

Machining titanium alloys generates approximately 10 times more vibration than steel. As the heat of cutting is concentrated in the cutting section, it produces jagged chips and causes fluctuations in cutting power.

Useful Tips for Machining Titanium

Cooling

Use coolant to reduce high cutting temperatures. Insoluble oil coolant is suitable for low-speed heavy-duty cutting, and soluble cutting coolant is suitable for high-speed cutting. Low-temperature cutting methods, such as using liquid nitrogen (-180°C) or liquid CO2 (-76°C) as cutting fluid, can effectively reduce the temperature of the cutting zone, improve the quality of machined surfaces, and prolong the life of cutting tools.

Selection of Suitable Cutting Tools

The selection of appropriate cutting tools can significantly improve machining efficiency. Since the heat of titanium alloy mainly relies on the cutting edge and coolant to be dispersed, instead of being discharged through the chips as in the case of steel, the tiny part of the cutting edge needs to withstand great thermal and mechanical stresses. Keeping the cutting edge sharp reduces the cutting forces. Where necessary, coated tools can be used to minimize the stickiness of the alloy and to break up excessively long chips.

Constant Feed or Increased Feed Rate

During cutting, the hardness of titanium alloys increases, which accelerates tool wear. Therefore, maintaining a constant feed is essential to minimize work hardening. If equipment performance allows, try increasing the feed rate to minimize the chance of heat buildup and work hardening.

How to Choose the Right Cutting Tools for Machining Titanium？

When CNC machining titanium, it is often challenging to use the right cutting tools, and here are the factors that should be considered:

Number of Edges on Cutting Tools

For titanium, the more the number of edges, the less the vibration pattern. To get shorter machining cycles, you must increase the number of chip flutes in your milling tool. For example, a 10-flute end mill has a low chip load for most materials, but is ideal for titanium. This primarily reduces radial engagement.

Tool Geometry

Selection of suitable tool geometry, including cutting angle, front angle, rear angle, can reduce the cutting force and reduce the cutting heat. When machining titanium alloy, a smaller front angle should generally be selected, which can significantly improve its cutting edge strength and chipping resistance; the selection of a larger rear angle can reduce the contact area between the back of the tool and the transition surface and the machining surface.

High Feed Milling Cutter

High feed milling cutters are suitable for maintaining low engagement when machining axial and radial titanium. High feed milling cutters are ideal for minimizing interaction when machining titanium in the radial direction using a 5-axis CNC.

Cutting Tool Coatings

Coatings can be effective in reducing friction and improving the high temperature resistance of cutting tools.TiAlN (Titanium Aluminum Nitride PVD Coating) is an excellent coating used on a wide range of cutting tools. It is lubricating, prevents chip buildup, wear and chip welding, and is ideally suited to the temperatures used in CNC milling of titanium alloys.

Keeps Cutting Edge Sharp and Avoids Cutting Interruptions

Due to its low Young's modulus, titanium has high strength and elasticity. This means that in order to remove chips from the surface efficiently and without friction, we need to use sharp tools. Try to avoid intermittent cutting, as this type of cutting presses the chips into the sharp tool and may lead to premature tool failure.

Surface Finishes for Machined Titanium Parts

• Electrophoresis
• Bead Blasting
• Polishing
• Chroming
• Painting
• PVD Coating
• Powder Coating

Applications of Titanium Machined Parts

Titanium machined parts are durable, corrosion resistant and aesthetically pleasing. These properties make them suitable for use in a variety of industries

Aerospace

Titanium is an indispensable material in the aerospace industry due to its lightweight, excellent low-temperature toughness and high-temperature resistance. In the aerospace industry, titanium is used in the manufacture of rocket engine housings, artificial satellite housings, spacecraft, ultra-low temperature containers and storage tanks on manned spacecraft. In aircraft manufacturing, titanium and its alloys play an important role in the manufacture of aircraft turbine disks, blades, rivets, housings, fuselage structural components and so on.

Chemical

Titanium is often used in the petrochemical industry to manufacture heat exchangers, reactors, storage tanks and other equipment due to its high level of corrosion and heat resistance. Especially in some occasions where high corrosion resistance is required, titanium is more widely used.

Medical

Titanium is widely used in medical devices due to its excellent biocompatibility, non-magnetic and corrosion resistance. Medical grade titanium is used in the manufacture of artificial joints, artificial bones, dental implants, pacemakers and other medical devices. These titanium products have good compatibility with human bones and tissues and can be implanted in the body for long periods of time without adverse reactions.

Automotive

Titanium has a light weight, good high temperature resistance and corrosion resistance, so it is increasingly widely used in the automotive industry, including the manufacture of engine components, connecting rods, crankshafts, exhaust systems, body and chassis parts. The use of titanium alloys to manufacture parts can significantly reduce the weight of automobiles, improve fuel efficiency and extend service life.

Marine

Titanium's corrosion resistance allows it to operate stably in seawater for long periods of time. Titanium made submarines, not only can resist seawater corrosion (according to experiments, titanium into the seabed for 20 to 50 years will not be corroded), but also resistant to deep pressure, its diving depth than stainless steel submarines increased by 80%. At the same time, titanium is non-magnetic, will not be found by mines, has a very good anti-guardian role. Often used in the manufacture of desalination equipment, offshore oil drilling equipment, ocean thermal energy conversion power plant.

Sports and Daily Goods

Titanium's corrosion resistance and aesthetics make it ideal for use in sporting and general merchandise. Titanium is consumed in huge quantities in the global golf equipment manufacturing sector, with upwards of 6,000 tons of titanium used in the manufacture of titanium golf equipment each year. In addition, titanium is widely used in tennis rackets, badminton rackets, ski poles, snow shovels, mountaineering poles, trekking spikes, sledges, fencing masks, fishing poles, bicycles, eyeglass frames, food utensils, watches, crafts, and other household items.

Titanium has a wide range of applications covering aerospace, chemical, medical, automotive, marine, sports and daily necessities. With the continuous progress of science and technology and the continuous improvement of titanium material performance, titanium applications will continue to expand.

Common Titanium Grades for CNC Machining

In CNC machining, the types of titanium and titanium alloys are mainly categorized according to their compositions and applications, the common types are Grade 1 titanium, Grade 2 titanium, Grade 3 titanium, Grade 4 titanium, Grade 5 titanium, Grade 6 titanium, Grade 7 titanium, Grade 23 titanium, etc. If you want to know more about titanium, then you must not miss our blog - what is titanium: the ultimate guide .

Choose DEK for Machining Titanium Parts

DEK is a professional and experienced CNC machining company specializing in machining titanium alloys. With state-of-the-art 5-axis machining centers and a team of highly skilled designers and engineers, we provide high-quality CNC machining of titanium alloys at competitive prices for a wide range of industries. Some of our success stories include impeller, antenna mounts and fasteners.

Conclusion

By reading this blog, you must have gained a comprehensive understanding of cnc machining titanium. Machining titanium and its alloys requires special attention and delicate handling to ensure optimal production of the part. Unlike common metals such as steel and copper, machining of titanium has its own unique challenges and necessitates the use of the right tools, specialized techniques and enough patience. For this reason, it is often better to outsource titanium CNC machining projects to a specialized team like DEK, where we can ensure the high quality and accuracy of the parts.

FAQs

What is the Cost of CNC Machining Titanium?

The cost of CNC machining titanium can vary depending on a number of factors, such as the complexity of the part, its size, the tolerances required, the quantity produced, and the grade of titanium used.

What Types of Cutting Tools are Commonly Used to Machine Titanium?

High-speed steel (HSS) tools; Carbide inserts; Ceramic inserts and Polycrystalline diamond (PCD) tools

What is the Cutting Speed of Titanium?

When CNC machining titanium, low cutting speeds are recommended. Tool tip temperatures can be easily increased by higher cutting speeds, which can compromise tools.

Does Titanium Warp When Machined?

Titanium can warp when machined due to its low thermal conductivity and high strength, which cause heat buildup and residual stresses. Proper cooling and machining techniques are necessary to minimize warping.