Titanium is a remarkable material for CNC machining. It can withstand high temperatures and is resistant to chemical corrosion. Furthermore, it is lightweight and has several other features that make it unique and attractive to manufacturers.
CNC machined titanium parts are extremely durable, but machining titanium can be challenging due to its high tensile strength. In this article, we will provide valuable information about CNC machining of titanium, how to choose the right cutting tools for machining titanium, and provide useful tips for successful machining.
Why choose titanium for CNC machining parts?
The main advantages of CNC titanium as a manufacturing material include its excellent biocompatibility, high degree of corrosion resistance and the highest strength-to-weight ratio of any metal. This metal also has excellent ductility and good machinability. Other reasons to choose titanium for CNC machining parts include:
- Durability: Titanium is extremely durable and ideal for producing CNC machined parts that are subject to harsh or extreme working conditions.
- Non-magnetic: This metal does not have magnetic properties. It also has excellent oxidation resistance and is therefore resistant to corrosion.
- Non-toxic: Titanium is corrosion resistant, has high biocompatibility and is non-toxic, making it ideal for use in the medical industry.
These properties allow titanium to be used in a variety of industries, including aerospace, medical and automotive.
Challenges to consider when machining titanium
While CNC titanium is an excellent material for many applications, manufacturers often face challenges when machining it. These challenges include:
High chemical reactivity and abrasion
When machining titanium alloys, some gases can react with them, causing problems such as surface oxidation and embrittlement. This can weaken components and reduce their corrosion resistance.
Furthermore, this metal has a low modulus of elasticity compared to its high resistance, making it a rubbery material for machining. Because titanium is rubbery, it can stick to the CNC cutting tool, causing errors and damage. In addition to tool damage, wear often affects the surface quality of titanium.
Heat development and cutting forces
Maintaining a low temperature when machining titanium is one of the biggest challenges. The reason for this is that titanium has low thermal conductivity, which causes heat to quickly accumulate in the metal part in the places where the tool works. This leads to faster wear and can have a negative impact on the quality of cutting surfaces if ignored, especially when machining harder titanium alloys.
For these harder titanium alloys, it is essential to use a higher chip load and a lower speed on the CNC machine. High-pressure coolant can also help your cutting tools work more efficiently and produce higher quality titanium parts.
Furthermore, titanium alloys require high cutting forces, which makes cutting difficult. These cutting forces often result in tool wear, defective parts and severe vibrations, which in turn affect product quality and surface finish.
Residual stresses and hardening stresses
Due to their crystalline structure, titanium alloys are not particularly flexible, which can cause problems during machining. Its crystalline structure can increase cutting force during machining, reduce machining ease, and increase the likelihood of residual stresses. These stresses can cause the position to warp, crack or last less.
Useful Tips for Machining Titanium
Many machine shops are hesitant to work with this cutting-edge material due to the difficulty of machining titanium. However, due to its exceptional properties, many manufacturers choose to use titanium to produce high-quality parts. Fortunately, experienced CNC machinists and toolmakers have developed helpful tips for machining titanium.
Attach parts securely
Anything you can do to reduce vibration will make machining titanium easier, since titanium is already susceptible to tool vibration. Clamp the parts securely to avoid deformation of the workpiece. Also use top-of-the-line CNC machines with extremely rigid tool layouts. To minimize tool deformation, you might even consider using shorter cutting tools.
Choose the right cutting tool
Due to the increasing demand for titanium, tool manufacturers are developing new strategies to improve the machinability of titanium. Cutting tools with titanium carbon nitride (TiCN) or heat-resistant titanium aluminum nitride (TiAlN) coatings can last longer.
In general, machinists should choose the highest quality titanium-specific tools and regularly inspect and replace worn equipment. Additionally, consider using a smaller diameter tool with more cutting edges to ensure the part removal rate remains consistent while limiting heat generation.
Consider cutting parameters
When machining titanium, the temperature must be carefully controlled. One of the easiest ways to keep the workpiece and tool cool is to apply constant, high-pressure coolant to the cutting area. When you blow the chips out of the cutting area, they do not stick to the machining tools.
Additionally, when working with titanium, it is important to consider feed rates, spindle speeds, and chip loads. This means limiting exposure to tools and equipment and avoiding staying in one place for too long. An alternative cutting strategy such as B. Increasing the axial depth of cut while reducing radial engagement may also be worth considering to increase cutting performance and reduce machining temperatures.
Prevent overheating by using a high-pressure cooling system
Titanium finishing requires a very small percentage of the tool radius to be in contact, a super sharp tool with very low feed per tooth. However, this creates heat that is difficult to remove from the work area. If it persists, it will end up ruining our cutting tools and the effects of heat will make it difficult to maintain tolerances. Therefore, use the best possible coolant setting when cutting titanium.
An effective aid is high pressure cooling. Depending on the application, a spindle may also be essential. When machining titanium, increasing coolant concentration can also be beneficial.
Different Types of Titanium for CNC Machining
There are different grades of titanium and types of titanium alloy, each with its ideal application, advantages and disadvantages. Let's examine these qualities in detail.
Grade 1 (pure titanium with low oxygen content)
This is the softest and most ductile titanium alloy among the most commonly used types of titanium. Grade 1 titanium has excellent machinability, impact resistance, corrosion resistance and formability. On the other hand, its resistance is lower compared to other types of titanium. This grade is used in the medical, automotive and aviation industries.
Grade 2 (pure titanium with standard oxygen content)
This is also known as a worker titan. It has high corrosion resistance, strength, formability, weldability, ductility and low strength. Grade 2 titanium is used in the medical and aerospace industries to manufacture aircraft engines.
Grade 3 (pure titanium with medium oxygen content)
Although not as commercially popular as grades 1 and 2, this titanium has good mechanical properties. It is highly resistant to corrosion, machinable and robust. It is used in the medical, marine and aviation industries.
Grade 4 (pure titanium with high oxygen content)
This type of titanium has high strength and corrosion resistance. However, it is not easy to machine because large amounts of coolant and feed rates are often required. Grade 4 titanium is used in cryogenic vessels, CPI devices, aircraft components, heat exchangers, etc.
The grades 1 to 4 mentioned above are all made of pure titanium. The next section deals with the different grades of titanium alloys.
Grade 5 (Ti6Al4V)
Grade 5 titanium alloys contain 4% vanadium and 6% aluminum. They are not as strong as other alloys, but they have high corrosion resistance and formability. They are ideal for power generation, offshore and marine applications, and critical aircraft structures.
Grade 6 (Ti 5 Al-2.5Sn)
This type of titanium has good stability, strength and weldability, especially at high temperatures, making it suitable for use in the manufacture of airframes and jet engines.
Class 7 (Ti-0.15Pd)
This grade of titanium is similar to grade 2. The only difference is the palladium content, which is added to improve corrosion resistance. Grade 7 titanium alloy has excellent formability and weldability. It is ideal for manufacturing chemical processing equipment.
Class 11 (Ti-0.15Pd)
Grade 11 titanium is quite similar to grade 7. However, it is more ductile and has a lower tolerance to other contaminants. It has strength below Grade 7 and is used in the marine and chlorate manufacturing industries.
Grade 12 (Ti0.3Mo0.8Ni)
Grade 12 titanium is quite expensive and contains 0.8% nickel and 0.3% molybdenum, which gives it excellent weldability, high temperature resistance and corrosion resistance. It is used in housings and heat exchangers, ship and aircraft components, etc.
Grade 23 (T6Al4V-ELI)
Grade 23 titanium, also known as extra low interstitial or TAV-EIL, has similar properties to grade 5 titanium but is purer. It has good fracture resistance and biocompatibility, but is relatively difficult to machine. It is used in the manufacture of orthopedic pins, screws, surgical brackets and orthodontic appliances.
How to choose the right cutting tools for machining titanium？
Using cutting tools in CNC machining of titanium is generally not a good idea. See how to choose the right cutting tools for milling titanium or when using other CNC machining techniques.
Consider the number of cutting tool blades
You need to increase the number of end mill flutes to improve product cycle times. With titanium, more teeth mean less vibration. For example, a 10-flute end mill is narrow for ideal chip loads for most materials, but is perfect for use with titanium. This is mainly due to the need to reduce radial interventions.
Avoid interrupted cuts and keep the blade sharp
Due to its low modulus of elasticity, titanium is strong and elastic. This means we need a sharp tool to remove chips from the surface efficiently and without friction.
Avoid interrupted cuts as much as possible, as this can introduce chips into your sharp-edged tools, potentially leading to premature tool failure.
Consider Coating Cutting Tools
Coatings can significantly improve your tools' ability to withstand the heat generated by titanium. A suitable coating is TiAlN (aluminum titanium nitride). It provides lubrication to prevent the formation of built-up edges, galling and chip welding and is particularly suitable for the temperatures encountered during machining.
Try using high feed cutters when machining titanium
High feed cutters are suitable for low contact depth in axial and radial machining of titanium. These tools are specifically designed to perform this task effectively.
Surface finishing for machined titanium parts
A number of surface finishing techniques, including titanium polishing, can improve CNC machined titanium products for functional and aesthetic reasons. These surface treatments include:
- polishing
- Anodizing
- Chrome plating
- Powder coating
- PVD Coating
- to brush
Applications of Titanium Machined Parts
Parts made from titanium are durable, corrosion-resistant and aesthetic. Thanks to these properties, they can be used in countless industries.
Maritime/navigation industry
Compared to most natural metals, titanium has greater corrosion resistance. This durability makes it ideal for manufacturing propeller shafts, underwater robots, mooring equipment, ball valves, marine heat exchangers, fire tubes, pumps, exhaust pipe linings and integrated refrigeration systems.
Aerospace
Due to its numerous desirable properties, titanium is a highly sought after material in the aerospace industry. These properties include its high strength-to-weight ratio, excellent corrosion resistance and suitability for extremely hot environments. Titanium parts in the aerospace industry include seat components, turbine components, shaft, valve, housing and filter parts, and oxygen generation system parts.
Auto Industry
In the automotive sector, titanium versus aluminum is always a hotly debated topic, with aluminum having the advantage due to its availability and cost-benefit. However, titanium is still used in the manufacture of automotive parts. The main applications of titanium and its alloys in the automotive industry are the manufacture of valves, valve springs, seals, automatic stop brackets, overhead lug nuts, engine piston pins, suspension springs, brake caliper pistons, rocker arms engine and connecting rods of internal combustion engines.
Medicine and dentistry
Due to its high corrosion resistance, low electrical conductivity and physiological pH values, titanium has numerous applications in the medical industry. Titanium parts used in the medical industry include tapered, straight or self-tapping bone screws, screws for dental implants, skull screws for cranial fixation systems, spinal fixation rods, connectors and plates, orthopedic pins, etc.
Choose WayKen to machine titanium parts
Concluding
Common questions
Is titanium harder to machine than steel?
Titanium is more difficult to machine than steel, mainly due to its high melting point. It is also very malleable and often stretches before breaking, making it difficult to work with.
What is the feed rate when milling titanium?
When machining titanium, this insert must be cut at a speed of 40 to 150 m/min and a feed of 0.03 to 0.15 mm per tooth.
How to make titanium stress-free after processing?
Stress relief techniques can be applied to titanium alloys without compromising their ductility or strength. Forgings are made by heating metal to temperatures between 595 and 705 °C (1100 and 1300 °F) for one to two hours before allowing it to cool in air.
