**2. Application of aluminum alloy 7075**

The increasing application of Al 7075 in the automotive and aerospace industries generally contributes to the reduction of the total mass of the vehicle. In the aerospace industry, Al 7075 is commonly used to produce structural components of the airframe, including wing skins, empennage or tail, and fuselage. The high corrosion resistance, high strength, high crashworthiness and durability of Al 7075 make the material desirable for structural components applications [2]. Typical mechanical properties for Al 7075 are shown in **Table 1**.

The modulus elasticity of AI 7075 is 71.7 GPa and its shear modulus is 26.9 GPa, which makes it suitable for high-performance metal application. Moreover, AI 7075 has a good tensile yield strength which means it could resist up to 503 MPa of tension before being deformed and will not revert to its initial form. The main reason for the high strength of Al 7075 compared to pure Aluminum is due to the zinc content as its primary alloying element [1]. The weight reduction while maintaining the strength of the component is advantageous to reduce fuel consumption and reduce maintenance costs. These good properties show the benefit and the reasons for Al 7075 is increasingly being used in industries for structural components.

From the aspect of machinability, Al 7075 is more machinable than other high-performance metals such as steel, cast iron and titanium due to its better chip formation and can be sheared easily [3]. Compared to other high-performance alloys (e.g., steel and titanium), the cutting forces, cutting temperature and energy consumed in machining aluminum alloy are relatively low which makes them a good alternative for achieving high productivity [4]. However, producing good hole quality in Al 7075 in terms of dimensional accuracy and good machines surface


#### **Table 1.**

*Typical mechanical properties of Al 7075 tempered [1].*

finish can be challenging. The soft and ductile properties of aluminum alloy could lead to thermal softening on the material during the operation which causes builtup edge formation that accumulated at the tool edge and material adhesion on the machined surface. Consequently, this leads to poor machined surface finish and hole quality. Hence, this chapter discusses the crucial drilling parameters that need to be considered to produce the required good hole quality.
