Technology Analysis of Precision Machining of Titanium Alloys
Introduction
The titanium alloys are a group of light weight yet high strength metals, which are extensively used in several industries. The range of available titanium alloys is quite common, but the majority of these alloys are still sourced from alloys developed during the 20th century. Due to the presence of strong yet lightweight properties and because titanium does not corrode in most environments, making it an ideal material of choice in aeronautical and other high-tech applications. As such, precision machining of titanium alloys has become increasingly important to ensure the performance of these products, for example in the aerospace industry, where the processing and machining of titanium alloys is used for aircraft engines and other high-performance components.
The main challenge faced by the machining engineers when working on titanium alloys is how to make the components with tight dimensional tolerance and surface finish requirements that are expected in the aerospace industry. Moreover, the difficulty is also seen in achieving the desired material removal rate and tool life while machining titanium alloys. To this end, machining specialists must be able to understand the basic principles of machining titanium alloys to make components with the desired features.
Process Selection
Given that different titanium alloys may require different machining processes, the selection of machine process is of the utmost importance when machining titanium alloys. Generally, for the production of parts with higher precision, using the latest and advanced machining technologies, such as carbon fiber reinforced composites (CFRP), are used instead of conventional machining processes. This is because CFRP machining offers greater precision and accuracy, as well as faster machining speeds. Other machine processes, such as Electrical Discharge Machining (EDM) and CNC machining ( turning, milling or grinding) can also be used for precise machining of titanium alloys.
Grinding
Grinding is one of the most common machining processes for precise machining of titanium alloys. A grinding wheel is used to make precise cuts and to shape the component according to customer requirements. Depending upon the component application, grinding can be done using wet or dry grinding. With wet grinding, a lubricant, such as a mineral oil, is added to the grinding wheel to keep the component cool and reduce the amount of heat generated. Dry grinding, on the other hand, minimizes the risk of fire and is suitable for dealing with biological safety risks. The grinding wheel used should be made of diamond or silicon carbide and should have a high specific energy, to improve the machining efficiency.
Milling
Milling is another commonly used process for precision machining of titanium alloys. The cutting speed and feed rate of the milling tool should be carefully selected, because the cutting forces generated by the tool can impair the component’s accuracy and surface finish. To reduce the amount of heat generated and avoid component distortion, coolant should be used for milling titanium alloys. Moreover, for faster and accurate machining, CNC milling machines should be used.
Turning
Turning is another machining process used for precision machining of titanium alloys. For precise turning of titanium alloys, high-speed turning machines with cutting tools made of high-durability ceramic materials should be used. The cutting speed, feed rate and tool life should also be taken into consideration when machining titanium alloys.
Electrical Discharge Machining (EDM)
EDM is a common machining process used for precision machining of titanium alloys. With EDM, a spark of electricity is used to cut the material. The sparks follow the contours of the component, making the cutting of complex shapes and intricate details easier, thereby minimizing material wastage. However, EDM machining generates a large amount of heat, so an efficient cooling system is required.
Tool Selection
The selection of tool is another important factor when working on titanium alloys. The cutting tools should be made from high-durability, high-precision materials, such as tungsten, vanadium and cobalt. The cutting edges of the tools should have a special coating, such as titanium nitride or diamond-like carbon, to improve the cutting speed and tool life.
Conclusion
Precision machining of titanium alloys is a complex process and requires the expertise of an experience machining engineer. The selection of the right machining process and tool will improve the efficiency of the machining process and ensure that the desired precision and dimensional tolerance are achieved. In addition, proper coolants and lubricants should be used to ensure that the component does not distort and is accurately machined.
