Titanium is an exceptional CNC machining material. It can tolerate high temperatures and is corrosion and chemical-resistant. Furthermore, it is lightweight and has various additional characteristics that make it unique and valuable for producers.

CNC-machined titanium parts are incredibly durable, but due to titanium’s high tensile strength, they can be challenging to manufacture. In this post, we will cover CNC machining titanium, how to choose the correct cutting tools for machining titanium and helpful hints for successful machining.

What Is Titanium?

Titanium is a beautiful transition metal discovered in the United Kingdom in the 18th century. It has a silvery look and is extremely strong despite its small density. This makes it a desirable commodity in businesses where weight reduction is critical.

Titanium has a high strength-to-weight ratio, is highly resistant to corrosion (from seawater, chlorine, and acids), and is non-toxic even in large quantities. This makes it very valuable in the medical field, where implants and other medical equipment are used.

Titanium is frequently alloyed with elements such as iron, aluminum, and vanadium in the industrial industry.

Why CNC Machine Titanium?

Titanium
Titanium

CNC titanium’s primary advantages as a manufacturing material include excellent biocompatibility, high corrosion resistance, and the highest strength-to-weight ratio of any metal. This metal is also highly malleable and machinable. Other benefits of using titanium for CNC precision titanium machining parts include:

  • Non-toxic

Titanium is corrosion-resistant, has excellent biocompatibility, and is non-toxic, making it a perfect material for usage in the medical business.

  • Non-magnetic

This metal has no magnetic properties. It is also resistant to corrosive effects due to its superior oxidation resistance.

  • Durability

Titanium is extremely strong, making it perfect for the production of CNC machined parts subjected to hard or extreme working conditions.

Why Choose Titanium For CNC Machining Parts?

Titanium drill bits
Titanium drill bits

CNC machining is usually the optimum manufacturing technology for getting the most accurate and economical titanium parts. To understand why, consider the alternatives. Casting titanium parts is rarely used by manufacturers. This is because heated titanium interacts severely with oxygen, and many refractory materials used in casting contain trace amounts of oxygen.

A remedy is to utilize rammed graphite casting, which produces parts with a highly rough surface texture unsuitable for most medical, aeronautical, and industrial applications. Titanium pieces can also be cast by lost wax casting. However, this needs a vacuum chamber. 

For titanium pieces, a recent approach is to use additive manufacturing. Titanium 3D printing materials can be processed using a variety of 3D printing procedures, including Selective Laser Melting (SLM), Direct Energy Deposition (DED), and Electron Beam Melting (EBM). However, these 3D printing technologies are expensive, and many sectors still need to validate 3D-printed titanium for safety-critical end-use parts. In comparison to the alternatives, CNC machining tungsten produces titanium parts that are accurate, safe, adaptable, and inexpensive.

Why Is Titanium Hard to Machine?

Although CNC titanium is an excellent material for a variety of applications, producers frequently encounter difficulties when machining it. Here are some of the reasons titanium is hard to machine:

Hardening and Residual Stresses

Titanium alloys are not highly flexible due to their crystal structure, which may need fixing during machining. Their crystal structure may enhance cutting force during machining, reducing machining ease and raising the possibility of residual stresses. 

These stresses may cause the position to twist, crack, or last for a shorter period.

Increased Galling and Chemical Reactivity

Some gases can react with titanium alloys during machining, causing surface oxidation and embrittlement. It has the potential to degrade the components and lower their corrosion resistance.

Furthermore, due to its incredible strength and low modulus of elasticity, this metal is difficult to manufacture. Titanium, due to its sticky nature, may adhere to the CNC cutting tool, resulting in failure and damage. Aside from causing tool damage, galling frequently degrades the surface finish quality of titanium.

Cutting Forces and Heat Buildup

One of the most difficult tasks is maintaining a cool temperature while cutting titanium. This is because titanium has a limited thermal conductivity, which causes the metal workpiece to heat up where the tooling is rapid. This wears down faster and can have a severe impact on the quality of cut surfaces if not treated properly, especially when machining tougher titanium alloys.

These harder CNC titanium alloys require a higher chip load and a lower RPM on the CNC machine. A high-pressure coolant can also make your cutting tools work more efficiently and produce higher-quality titanium pieces.

Titanium alloys also require large cutting forces, making them difficult to cut. These cutting forces frequently result in tool wear, defective parts, and high vibration, affecting product quality and surface polish. 

Useful Tips for Machining Titanium

Metalworking CNC
Metalworking CNC

Because of the complexities of titanium machining, many machine shops are hesitant to work with this cutting-edge material. However, because of its outstanding properties, many manufacturers are using titanium to build high-quality parts. Fortunately, competent CNC machinists and tool manufacturers have produced helpful machine titanium tips.

Here are the machining titanium tips:

Choose the Right Cutting Tool

Because of the increased demand for titanium, tool makers are researching unique ways to improve the machinability of titanium. Cutting tools with titanium carbo-nitride (TiCN) or heat-resistant titanium aluminum nitride (TiAlN) coatings can persist longer.

Overall, machinists should select titanium-specific tools of the highest quality and inspect and replace worn-out equipment regularly. Also, try utilizing a tool with a smaller diameter and more cutting blades to help maintain a consistent workpiece removal rate while limiting heat accumulation. A good rapid prototyping company will ensure this is done.

Fasten Parts Tighthly

Because titanium is prone to tool chatter, whatever you can do to reduce vibration will make machining titanium easier. Fasten pieces tightly to prevent workpiece deflection. In addition, use high-quality CNC machines with exceptionally stiff tooling configurations. You might also consider using shorter cutting tools to reduce tool deflection.

Use High-Pressure Cooling System 

Titanium CNC finishing requires a tiny percentage of the tool’s radius being in contact, as well as a razor-sharp, very low feed per tooth. However, it will result in heat that is difficult to remove from the work area. If we leave it alone, it will eventually destroy our cutting equipment and make keeping tolerances difficult. As a result, when cutting titanium, use the best coolant configuration available.

A high-pressure cooling system is an effective assistance. Depending on the application, a spindle may also be required. When working with titanium, increasing coolant concentration may also be useful.

Consider Cutting Parameters

When machining titanium, temperature control must be utilized with caution. One of the simplest ways to keep the workpiece and tooling cool is to use a constant stream of high-pressure coolant directed at the cut region. If you blast the chips out of the cut zone, they won’t stick to your machining equipment.

When working with titanium, you must also consider your feed rates, spindle speeds, and chip loads. This includes limiting the stress exerted on tools and equipment and avoiding staying in one spot for too long. To boost cutting efficacy and minimize machining temperatures, an alternate cutting approach, such as increasing axial cut depth while decreasing radial engagement, may be worth studying.

Different Titanium Grades For CNC Machining

Rainbow Titanium Black Tourmaline
Rainbow Titanium Black Tourmaline

There are various types of titanium alloys and grades of titanium, each having its suitable application, advantages, and disadvantages. Let’s take a closer look at these grades:

Grade 1

This is pure titanium with low oxygen content. It is the softest and most ductile titanium alloy among the most often used titanium kinds. Grade 1 titanium is extremely machinable, impact-durable, corrosion-resistant, and formable. On the negative, it has a lower strength than other types of titanium. This level is used in the medical, automotive, and aerospace industries.

Grade 2

This is pure titanium with standard oxygen content. It is often referred to as workhorse titanium. It is very corrosion resistant, strong, formable, weldable, ductile, and has a low strength. Grade 2 titanium is used in the medical and aerospace industries to make aircraft engines.

Grade 3

This is pure titanium with medium oxygen content. Although less often used than grades 1 and 2, this titanium offers excellent mechanical qualities. It provides excellent corrosion resistance, machinability, and strength. It is used in the medical, maritime, and aerospace industries. 

Grade 4

This is pure titanium with high oxygen content. This titanium grade is solid and corrosion-resistant. However, it isn’t easy to manufacture, necessitating large amounts of coolant and a high feed rate. Grade 4 titanium is used in cryogenic containers, CPI equipment, airplane components, heat exchangers, and other applications.

Grade 5

This is also known as Ti6Al4V. Titanium alloy grade 5 comprises 4% vanadium and 6% aluminium. It is not as strong as other alloys, but it is highly corrosion-resistant and formable. It is well suited to power generating, offshore and maritime applications, and crucial airframe structures.

Grade 6 

This is also known as Ti 5 Al-2.5Sn. This titanium grade provides good weldability, stability, and strength, mostly at high temperatures, making it useful in the manufacture of airframes and jet engines.

Grade 7

This is also known as Ti-0.15Pd. This titanium grade is comparable to grade 2, with the sole difference being the addition of palladium to improve corrosion resistance. Grade 7 titanium alloy is very formable and weldable. It is appropriate for use in the manufacture of chemical processing equipment.

Grade 11 

This is also known as Ti-0.15Pd. Grade 11 titanium is quite comparable to grade 7. However, it is more ductile and has a lower tolerance for other impurities. It has a lower strength than grade 7 and is used in the maritime and chlorate production industries.

Grade 12

This is also known as Ti0.3Mo0.8Ni. Grade 12 titanium is costly and comprises 0.3% molybdenum and 0.8% nickel, which gives it good weldability, high-temperature strength, and corrosion resistance. It is used in shell and heat exchangers, marine and aerospace components, and so on.

Grade 23 

This is also known as T6Al4V-ELI or extra low interstitial. Grade 23 titanium has similar qualities as grade 5 titanium but is purer. It has a high fracture toughness, is biocompatible, and has a low relative machinability. It is used to make orthopedic pins, screws, surgical staples, and orthodontic appliances.

How To Choose The Right Cutting Tools For Machining Titanium?

Conical step drill bit for sheet metal hole drilling
Conical step drill bit for sheet metal hole drilling

When CNC machining titanium, using any cutting tool is usually a bad idea. Here’s how to select the best cutting tools for milling titanium or other custom titanium machining techniques like Titanium lathe turning:

Consider the Cutting Tool’s Number of Flutes

To obtain product cycle times, you must increase the number of end mill flutes. More teeth = less chatter in the case of titanium. For example, a 10-flute end mill, while tight for the chip loads required for most materials, is ideal for usage with titanium. This is primarily due to the requirement to limit radial engagements.

Consider High-Feed Mills 

When working with 5-axis CNC machining and radially oriented titanium, high-feed mills are ideal for minimizing interaction. These tools are designed expressly to do that purpose.

Consider Cutting Tool Coating 

Coatings can significantly improve your tooling’s ability to withstand the heat produced by titanium. TiAlN (Titanium Aluminium Nitride) is an excellent coating to think about. It provides lubricity to combat built-up edges, galling, and chip welding and is particularly well suited to the temperatures encountered during CNC milling titanium.

Keep Cutting Edge Sharp and Avoid Interrupted Cuts

Titanium is strong and elastic due to its low Young’s modulus. This means that a sharp instrument is required to remove a chip from the surface efficiently and without friction.

Interrupted cuts should be avoided as much as possible since they can hammer chips into your sharp-edged tools, potentially leading to early tool failure.

Surface Finishes for Machined Titanium

CNC-machined titanium CNC parts can benefit from a range of surface finishing treatments, whether for functional or aesthetic reasons.

Titanium surface finishing includes:

  • Smoothing
  • Electrophoresis
  • Bead blasting
  • Brushing
  • Polishing
  • Chroming
  • Painting
  • Metalizing
  • PVD coating
  • Powder coating

Applications Of Titanium Machined Parts

Metal drill bits
Metal drill bits

Titanium-machined products are long-lasting, corrosion-resistant, and aesthetically pleasing. These characteristics enable them to be used in a wide range of industries. Here are some of their applications in various industries:

Medical and Dental

Titanium has various applications in the medical business due to its strong, low electrical conductivity, corrosion resistance, and physiological pH values. Titanium medical parts include tapered, self-tapping, or straight bone screws, dental implant screws, cranial screws for cranial fixation systems, spinal fixation rods, orthopedic pins, connections, and plates, and so on.

Marine/Naval Industry

Titanium has a stronger corrosion resistance than most naturally occurring metals. Because of its resistance, it is perfect for the manufacture of propeller shafts, underwater robotics, ball valves, rigging equipment, marine heat exchangers, pumps, exhaust stack liners, fire system piping, and onboarding cooling systems.

Automotive

Titanium vs. aluminum is a hot debate in the automotive industry, with aluminum having the upper hand because of its availability and cost-effectiveness. Nonetheless, titanium is still used in the manufacturing of automobile parts. Titanium and its alloys are used mainly in the manufacture of valves, valve springs, retainers, car stop brackets, hanging ear nuts, engine piston pins, suspension springs, brake caliper pistons, engine rockers, and connecting rods for internal combustion engines.

Aerospace

Titanium is a popular material in the aircraft industry due to its multiple desirable properties. These characteristics include a high strength-to-weight ratio, exceptional corrosion resistance, and performance in highly hot settings. Seat components, housing, shaft, valve, turbine components, and filter parts, as well as parts for oxygen generation systems, are all made of titanium in the aerospace industry.

Conclusion

As you may know, the best titanium for your product is determined by the features and applications you require. If you are developing products for medical uses, you should consider grade 23 titanium. Alternatively, if you want a piece that will operate well at high temperatures, grade 6 titanium should be considered.

Just keep in mind that titanium alloys require precise machining by qualified professionals. Unlike free machining metals such as Brass C360 or Steel SS416, working with titanium demands skill, patience, and the proper tools. Look no further than Zintilon’s CNC machining services for your next titanium CNC service. Contact us today!

FAQs

What RPM Is Needed for Titanium Machining?

It is essential to use the proper and powerful titanium machines. Some of the recommendations for good titanium CNC milling machine include very high torque in machines, which is required and can range from 300-1500 Nm. Furthermore, low RPM, and in most circumstances, 3000 RPM, is sufficient because a carbide cutting tool with a soft cutting speed of 45-100 m/min is employed. Internal coolant is also required; the higher the temperature, the better.

What Is the Feed Rate of Milling Titanium?

This insert should be cut at a speed of 40 to 150 m/min and a feed rate of 0.03 to 0.15 mm per tooth when working with titanium.

Is Titanium Harder to Machine Than Steel?

Titanium is more difficult to process than steel owing to its high melting point. It is also highly pliable and frequently expands before breaking, making it difficult to machine.

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