How to Drill Titanium: The Aerospace Fever in Titanium Drilling 2023/05/31 About Titanium and its Common Use Titanium Material Properties Titanium alloys are metals composed of a mixture of titanium and other chemical elements. The most common form of titanium alloys is Ti-6Al-4V (Learn more about the crystallographic forms of Titanium Alloys). The Mohs hardness ranking of this form of titanium alloy is approximately 41HRC, which is not as hard compared to other metal alloys. This material offers a combination of lightweight, high strength, low density, good corrosion resistance and ductility. F1. titanium metal alloy material Titanium alloys are also recognized for their exceptional resistance to a wide range of chemical environments provided by a thin, invisible but extremely protective surface oxide film. The absorption of oxygen into the surface when the material is heated will cause an increase in hardness of the surface layer (Learn more about work hardening of Titanium Alloys). Common Applications of Titanium Its excellent material properties, including lightweight, high strength, good corrosion resistance and good ductility, make it the prime choice for many fields of applications, including aircraft turbines, engine components, aircraft structural components (wings and fuselage), aerospace fasteners, automotive components (body panels, valves), marine applications, etc. F2. bolts and engine parts made of titanium alloy Aerospace applications still account for the biggest chunk of the use of titanium alloys, due to its fine material properties of high strength, good fatigue resistance and fracture toughness. F3. Boeing 757-200 jet engine application in aerospace industry Tips and Common Tools for Titanium Drilling Titanium alloys require well-setup machining process to prevent the material from bending or surface hardening due to its low density, good ductility, and work hardening properties. Generally, the tool should be maintained as sharp as possible to minimize the built-up heat and tool wear. Using rigid setups between tool and workpiece to prevent the workpiece from bending due to its ductile characteristic. Proper cooling device is also strongly advised to lower the built-up heat. F4. drilling titanium alloy requires sharp and rigid drills When it comes to drilling titanium alloys, carbide drills are the best choice especially for deep hole drilling. Using sharp drills of proper geometry and avoiding having the drill ride through the titanium surface are also key to successful drilling on titanium alloys (Learn more about tips on successful drilling on Titanium Alloys). Difficulties in Titanium Drilling Titanium Drilling Challenges in Quality The good ductility and work hardening properties of titanium alloys have brought serious concerns for the quality of hole wall and the positional precision of the drilling holes. If the cutting (drilling) force is not well-controlled, the workpiece may suffer from displacement due to its ductile property. Its hardened surface and entangled chips will also cause severe damages to both the quality of workpiece and its positional precision. When it comes to higher aspect ratio (hole depth to diameter), it is going to be even more challenging to maintain the quality. Titanium Drilling Challenges in Tool Life The work hardening property of titanium alloys when it is heated has brought huge difficulties in drilling this material. With the protective oxide layer on the surface of titanium alloys, the drills may lose their sharpness easily and even encounter risks of tool breakage. Along with the entangled chips produced in the drilling process, not only the quality of workpiece is at stake, but also the tool life will be disastrously unstable. The major challenge also lies in controlling the cutting (drilling) force in the drilling process. F5. drilling process on a CNC machine HIT Achievements in Titanium Drilling HIT’s ultrasonic-assisted machining technology provides the superimposition of the tool rotation with a high-frequency oscillation in longitudinal direction, generating over 20,000 times of micro-vibration per second. The mechanism helps reduce cutting forces and facilitates chip removal process. F6. HIT's ultrasonic machining technology with high-frequency oscillation in longitudinal direction facilitates chip removal process The reduction in cutting forces not only decreases frictions between tools and workpieces, but also allows feed rates to be increased. This mechanism along with the high pressure (70bar) coolant through spindle (CTS) feature help lower the heat produced during the machining process. This greatly improves the quality of workpieces and the stability of tool life, and saves a huge amount of processing time. F7. HIT's ultrasonic machining technology helps reduction in cutting force, bringing more stability in tool life Facilitating chip removal process diminishes frictions on both tools and workpieces caused by excessive amount of chips. HIT’s ultrasonic high-frequency micro-vibration allows chips to break easily and lessens the occurrences of entangled chips. This also displays a great benefit to both the quality of workpieces and the stability of tool life. Drilling titanium alloys with ultrasonic-assisted machining technology, the reduction in cutting forces and improvement in chip removal process allow better control of the quality of workpieces and the stability in tool life. More information on HIT Ultrasonic Machining Technology Two Successful HIT Cases of Titanium Drilling Titanium Drilling Case 1 : Micro-Drilling F8. titanium alloy micro-drilling workpiece HIT discovered that conducting the Φ0.5x5mm micro-drilling 50 holes on titanium alloy (Ti-6Al-4V) with ultrasonic-assisted machining technology, the cutting force can be reduced by 39%. With the integration of CTS, it greatly reduced the occurrence of twisted or entangled chips. This not only prolonged tool life, but also maintained the positional precision of the micro-holes. F9. shape of chips in titanium alloy micro-drilling This feature is widely applied in the Aerospace industry and the 3C Electronics industry, especially being used for aircraft riveted components, phone cases, etc. More information on Titanium Drilling : Micro-Drilling Titanium Machining Case 2 : Side Milling F10. titanium alloy side milling workpiece HIT carried out side milling on titanium alloy (Ti-6Al-4V). Using HIT’s ultrasonic tool holder BT30 with the integration of CTS, ATC, and CNC automation system, HIT managed to greatly improve the tool life. It only showed a minor broken corner on the rake face of the tool, instead of severe tool wear such as the exposure of coating grains. F11. rake face of the tool in titanium alloy side milling F12. shape of chips in titanium alloy side milling This feature is widely applied in the Aerospace industry and 3C Electronics industry, especially being used for aircraft structural components, phone cases, etc. Titanium Drilling FAQ Q1 How to control the cutting (drilling) force while reaching the required quality of the drilling holes? A1 HIT’s ultrasonic-assisted machining technology provides the superimposition of the tool rotation with a high-frequency oscillation in longitudinal direction, generating over 20,000 times of micro-vibration per second. The mechanism helps reduce cutting forces and facilitates chip removal process. HIT’s ultrasonic high-frequency micro-vibration allows chips to break easily and lessens the occurrences of entangled chips. With the assistance of high pressure (70bar) coolant through spindle (CTS), it allows the chip removal process even smoother. These features can successfully bring better quality of the workpieces and longer, more stable tool life. F13. HIT ultrasonic machining driver module More information on HIT Ultrasonic Machining Module Q2 How to adjust feed rates and amplitude when I start drilling titanium alloys with HIT’s ultrasonic machining module system? A2 HIT aims to help clients face the challenges in drilling titanium alloys. This includes providing the optimum machining parameters and services to ensure clients having the best experiences in using HIT’s ultrasonic machining module system. It is not just buying a product from HIT, but obtaining the knowledge, services, and efforts from the most professional team. F14. HIT ultrasonic tool holders Titanium Drilling? Choose HIT Contact us if you are looking for a better way to improve machining efficiency, quality, and tool life. *References : 1. Nuclear Power – Titanium Alloys 2. AZO Materials – Titanium Alloys – Physical Properties 3. RMI Titanium Co. LLC – Titanium Alloy Guide 4. Total Materia – Titanium Properties 5. Metallurgical Engineering – Introduction to Titanium and its Alloys. ←Back