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Titanium is a strong, lightweight material that is resistant to heat and corrosion, making it a valuable choice in many industries. It is lighter than steel yet remains strong. Therefore, it is the preferred choice for use in aerospace, medical, and military applications.
Titanium machining can be challenging because it is a tough material. During machining, it generates a significant amount of heat. This can wear down tools quickly. With the right tools, cutting speeds, and cooling methods, CNC machining of titanium can be done smoothly and accurately.
How Titanium CNC Machining Works
A well-planned process for machining titanium is needed due to its strength and thermal properties. Additionally, titanium can generate heat while being cut and may damage your tooling if proper care is not taken. Each operation should be carefully planned to minimise excessive heat generation and tool wear.
Cutting Tool Selection
Titanium Cutting Tool
Selecting the correct cutting tool for titanium machining is essential. As titanium produces considerable heat during cutting, the cutting tool chosen must be able to withstand high temperatures. High-speed steel (HSS) coated cutting tools provide the best performance when cutting titanium. HSS cutting tools are made from tungsten, carbon, and vanadium and remain hardened at elevated temperatures, providing a smooth cut and reducing tool wear and damage.
Coatings
Cutting tool coatings help keep the tool cool and extend its life. Titanium Aluminium Nitride (TiAlN)Â is an excellent coating option for machining titanium. The TiAlN coating provides a protective barrier on the tool surface, preventing heat transfer from the tool to the workpiece. Most of the generated heat is transferred through the chip rather than the tool.
Surface Stability
Due to titanium’s flexibility, it is prone to vibrations during machining operations. Excessive vibration can result in damage to either the tool or the part. Establishing a stable machining environment can be achieved by using a short-length tool and a larger-diameter end mill. Maintaining a consistent cutting speed and feed rate will prevent excessive heat buildup and tool drag.
Climb Milling
When machining titanium, climb milling is recommended for optimal results. It produces a thicker chip that gradually decreases in size, which maintains the majority of the heat in the chip. Climbing milling provides clean cuts and reduces tool wear. In addition to providing clean cuts and reduced tool wear, it also minimises the occurrence of chips clogging the cutter and allows for smoother cutting.
Reasons Why Titanium Is Used for Custom Metal Machining Applications
Titanium sheet metal is among the most versatile materials now used by modern industry. Because titanium is the 4rth-most abundant metallic element in the Earth’s crust, this metal combines an unusual combination of great strength, small size (lightness), and remarkable durability. Therefore, it is increasingly being utilised in the aerospace industry, the marine industry, the chemical process industry, and the medical industry.
Strength/Lightness
Titanium is both robust and light. On average, it is about 60% heavier than aluminium; however, it is over twice as strong as aluminium. Additionally, titanium has similar strength features to many steel alloys and is often stronger. Furthermore, it is relatively flexible (ductile) and is non-magnetic. Additionally, because of its low thermal conductivity, titanium performs exceptionally well in high-temperature environments. Finally, the high fatigue limit of titanium means that it will withstand extreme conditions for an extended period.
Resistance to Corrosion
Another significant benefit of titanium is its inherent resistance to corrosion. Upon exposure to oxygen in the air, it creates a thin film of oxide that protects it from additional oxidation. Thus, titanium resists corrosion from acids (such as sulfuric acid and hydrochloric acid), chlorides, and many organic compounds. Since titanium can maintain its structural integrity in corrosive environments, it can be used in chemical processing facilities where other metals would rapidly corrode.
Biocompatibility
Titanium is considered to be the most biocompatible metal currently available. Since it does not react chemically with bodily fluids or tissues, it is the best material to use in medical applications. Titanium is capable of forming a bond with bone tissue, a process known as osseointegration. As a result, it is commonly used for surgical implants and dental applications. It is nontoxic and bioinert, meaning that it will neither harm nor interfere with the body’s normal functions. Titanium was first used successfully in dentistry in the 1940s and remains the preferred material today for surgical implants. Because it is nonmagnetic, patients with titanium implants can undergo MRI testing and other medical imaging procedures safely.
Useful Strategies for CNC Titanium Machining
The titanium machining process can become challenging; however, following the proper procedures can make it easier. Understanding the effects of temperature, pressure, and cutting forces on the material will help decrease tool wear, increase accuracy, and make machining titanium less challenging.
Maintain Low Tool Temperature
Titanium does not conduct heat efficiently; therefore, most of the generated heat remains in the cutting tool. High temperatures generated by excessive heat can dull or destroy the cutting edge of the tool. Additionally, high temperatures may cause strain hardening, which can further complicate the cutting process. The key to maintaining a healthy cutting tool is to ensure an adequate amount of cooling agent is applied to sustain low tool temperatures and prevent tool damage.
Make the Surface Stable
Galloping or vibrations can cause damage to both the tool and the workpiece. Upon initiating the cutting operation, start slowly and follow the contour of the workpiece with a smooth arc, rather than entering directly into the workpiece. A soft entry will minimise pressure on the tool and result in a clean cut. A chamfer at the end of each cut also minimises sudden application of pressure and stress to the tool.
Watch Your Tools
Due to titanium’s tendency to wear cutting tools rapidly compared to many other metals, inspect your cutting tool frequently and replace the tool as soon as it begins to dull. Sharp cutting edges create less friction, generate less heat, and reduce cutting time.
Leave Enough Space for the Tool
Using a smaller diameter cutting tool provides more clearance for air and cooling agents. This allows for better cooling of the tool and workpiece during the cutting process and minimises contact between the tool and workpiece, reducing the potential for excessive heat generation.
Minimize Galling
Titanium tends to “stick” to the cutting tool as it cuts, resulting in galling. Galling creates a poor surface finish and causes rapid wear to the cutting tool. Utilising sharp cutting tools, cooling agents, and lubricants will help eliminate galling and improve the surface quality of the workpiece.
Control Chipping
Chipping occurs when metal fragments become attached to the cutting tool, resulting in a buildup of material along the cutting edge. This makes rapid wear to the cutting tool and degrades the surface finish of the workpiece. Maintaining sharp cutting tools and using the correct type of lubricant will help minimize edge buildup and improve cutting tool performance.
Applications of Titanium Machining Across Different Industries
Titanium is one of the most versatile metals due to its exceptional strength-to-weight ratio, ability to withstand extreme temperatures, outstanding corrosion resistance, and exceptional durability.
Aerospace Applications
Titanium Aircraft Jet Engine
Laser cutting titanium has been extensively used in the aerospace industry in the construction of aircraft and spacecraft. Titanium enables the creation of strong yet lightweight aircraft that consume less fuel. In addition to its strength-to-weight advantage, titanium has a high melting point (approximately 1668°C) and is thus ideal for engine parts and body components of aircraft.
Military Uses
The military also utilises titanium in various applications, including missiles, submarines, and tanks. Due to its unique combination of strength and low weight, titanium is an ideal choice for military equipment that requires speed and efficiency.
Marine Applications
Due to its excellent performance in seawater and resistance to corrosion, titanium is widely used in marine applications, including propellers and pipes.
Medical Applications
Titanium is considered biocompatible and non-reactive with human tissue; thus, it is used in medical applications for implanting prosthetic limbs, artificial joints (such as hip replacements), bone plates, and pacemakers.
Dental Applications
Dentists have started using titanium for dental implants, bridges, and crowns. The primary reason behind this trend is that titanium is robust, durable, and resistant to corrosion.
Sports Industry
In recent years, titanium has been increasingly used in sports products, including golf clubs, bicycles, and tennis rackets. Its lightness, durability, and strength make it ideal for these applications.
Jewelry Industry
Titanium is also being increasingly used in jewelry making, particularly in the manufacture of rings, watches, and eyeglass frames. It is very durable, shiny, light, and resistant to scratches.
Key Takeaways
This article has explained the common uses and machining tips for titanium. By following the right machining guidelines, including the use of suitable tools, effective cooling methods, and stable setups, you can minimise tool wear, improve surface finish, and make titanium machining easier and more efficient.
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