Drilling Process in γ-TiAl Intermetallic Alloys

Abstract

Gamma titanium aluminides (γ-TiAl) present an excellent behavior under high temperature conditions, being a feasible alternative to nickel-based superalloy components in the aeroengine sector. However, considered as a difficult to cut material, process cutting parameters require special study to guarantee component quality. In this work, a developed drilling mechanistic model is a useful tool in order to predict drilling force (Fz) and torque (Tc) for optimal drilling conditions. The model is a helping tool to select operational parameters for the material to cut by providing the programmer predicted drilling forces (Fz) and torque (Tc) values. This will allow the avoidance of operational parameters that will cause excessively high force and torque values that could damage quality. The model is validated for three types of Gamma-TiAl alloys. Integral hard metal end-drilling tools and different cutting parameters (feeds and cutting speeds) are tested for three different sized holes for each alloy.

Sensitivity Analysis of Tool Wear in Drilling of Titanium Aluminides

“…So, a major drawback here is the lack of knowledge, i.e., of the best cutting conditions for reliable, reproducible, accurate but productive machining of these types of alloys. In a previous study [19], the authors presented a mechanistic and useful model to estimate cutting forces and torque. However, tool wear is a critical parameter causing the rapid growth of these stationary forces and torque.…”

“…For the experimental tests, a vertical machining center Kondia ® B640, with nmax = 10,000 rpm and Pnom = 5 kW was used ( Figure 2). The cutting parameters were selected according to the values recommended by the tool manufacturer and the past experience of the authors [19]. For the experimental tests, a vertical machining center Kondia ® B640, with n max = 10,000 rpm and P nom = 5 kW was used ( Figure 2).…”

“…Especially in drilling, thrust or feed force and torque are key parameters to keep the process under control. In [19], the authors, proposed the fitting of specific cutting coefficients when drilling some types of gamma TiAl. The corresponding coefficients for the feed force and torque were polynomial functions of chip thickness, hc, and radial distance from the cutting point to tool axis, r. In the present work, the authors go a step further in investigating wear, which is a critical parameter when considering the evolution of cutting forces and torque over time.…”

“…Polvorosa et al [17] studied wear mechanisms in nickel-based alloys and discussed the effect of using different coolant pressures. Beranoagirre et al discussed the machinability of gamma TiAl in EDM [18] and in drilling processes [19], where a mechanistic model was proposed for cutting force and torque prediction. Regarding soft titanium alloys, Kuczmaszewski et al [20] demonstrated that ultra-fine-grain SC milling cutters are the tools most resistant to chipping while leaving a good surface finish.…”

Complex Multi-System Integration Problems Associated with Titanium Metalworking and Manufacture: System of Systems Aproach—Part I

“…Gamma titanium aluminide intermetallics show an excellent strength-weight ratio, and corrosion resistance at high temperature [2]. Although Gamma titanium has promising application possibilities, drilling machinability studies are the main interest due to presented machinability problems [3]. In spite of the abundance and advantages of titanium metal, the difficulty in extracting titanium from ores, its high reactivity in the molten state, its forging complexity, its machining difficulty, and its sensitivity to segregation and inclusions required the development of special new design processing methods [4].…”