CNC Machining Titanium

Titanium alloys are widely used in fields such as aerospace, medical devices, automotive, construction, sports equipment, and more. Their characteristics include low density, high strength-to-weight ratio, low coefficient of thermal expansion, excellent thermal conductivity, high-temperature and low-temperature strength, corrosion resistance, non-magnetic properties, biocompatibility, and some special alloys with memory functions. In the future, titanium alloys are expected to replace traditional materials in more fields.

Titanium alloys are divided into different grades, mainly categorized into three series: TA (pure titanium and alpha-type alloys), TB (beta-type alloys), and TC (alpha+beta-type alloys). According to the Chinese standard GB/T 3620.1-2016, there are approximately 99 different grades of titanium alloys. The American standard uses “grade” to represent different levels, and there are about 34 different grades.

A-titanium, B-titanium, and AB-titanium are commonly used terms to distinguish different characteristics of titanium alloys. Grade titanium typically refers to titanium materials categorized into different grades based on their intended use and performance requirements. Medical-grade titanium is a high-purity titanium alloy used for manufacturing medical devices and implants. Regarding surface treatment, titanium alloys can undergo various processes such as anodization and micro-arc oxidation to improve hardness and wear resistance. Different processes require specific process conditions and safety measures.

Titanium alloys have significant differences in machinability compared to stainless steel. Due to their low thermal conductivity and tendency to stick to cutting tools, machining titanium alloys is notably different from machining stainless steel. Processing titanium alloys typically requires specialized tooling and cutting fluids to reduce friction and heat, and tool selection and cooling need to consider the characteristics of titanium alloys.

General cutting fluids can be used as coolants for titanium alloy turning and milling, and there are no special requirements. Titanium alloys are flammable, but the primary source of ignition is the chips, so measures to reduce flammability risk include reducing the depth of cut, ensuring adequate cooling, maintaining good ventilation, and avoiding open flames. In case of open flames, water should not be used directly to extinguish the fire; dry sand is a better option.

When machining titanium alloys, it’s recommended to use cutting tools with high-temperature hardness, wear resistance, compressive strength, bending strength, and impact toughness. Commonly used hard alloy cutting tools include YG8, YG6, and YW2. YG8 and YG6 contain cobalt and exhibit good wear resistance, while YW2 contains tungsten, tantalum (niobium), and cobalt, providing high bending strength. Proper tool selection and suitable cutting fluids can improve the machinability of titanium alloys.

The two primary processing methods for titanium screws are cold heading and machining. Cold heading is often used with TC2 titanium, which is relatively soft and exhibits good ductility. Machining is commonly used with TC4 titanium, which has higher hardness and better overall mechanical properties. The two methods differ in material and processing techniques. Machined titanium screws are typically more refined, with higher precision and can achieve tolerances of 0.01mm.

For processing titanium alloy threads, a cutting tap is a better choice. Due to the characteristics of titanium alloys, internal thread tapping can be a challenging process, especially for small hole threads. Cutting taps are more suitable than roll taps because roll taps tend to produce higher torque when used on titanium alloys, approximately twice that of steel. The teeth of roll taps are prone to wear, chipping, and even breakage. This is primarily due to the relatively low modulus of elasticity of titanium alloys, which results in significant springback after internal thread tapping, leading to high friction torque. Additionally, factors such as high temperatures, chip adhesion, and difficulties in providing cutting fluid to the cutting zone can contribute to the challenges of machining titanium alloys. To address these issues, it’s essential to optimize the geometry parameters of titanium alloy internal thread taps and select the appropriate tap based on the form of the hole, accuracy requirements, and machine conditions.

Titanium springs are typically manufactured using TC4 titanium alloy, known for its low elastic modulus and high fatigue strength, making it suitable for spring production. There are several main types of titanium springs, including tension springs, compression springs, and torsion springs. These titanium springs have various applications, including but not limited to:

Chemical Industry: Titanium springs are used in chemical equipment such as pumps and valves due to titanium’s corrosion resistance and chemical stability.

Marine Engineering: Titanium’s corrosion resistance is advantageous in seawater environments, making titanium springs suitable for underwater equipment and diving apparatus.

Automotive Manufacturing: Titanium springs can be used in vehicle suspension systems to reduce weight and improve fuel efficiency, thanks to titanium’s lightweight and high strength properties.

Aerospace: In the aerospace field, where lightweight, high-strength components are essential, titanium springs find applications in various aerospace components and systems.