# Wear Behavior of Uncoated and Coated Tools in Milling Operations of AMPCO (Cu-Be) Alloy
## 1 Introduction  
Copper-Beryllium alloys have seen application in a great variety of industries, such as aeronautics and aerospace [1], molds, and other applications that are subject to hazardous conditions. These alloys are preferred over other copper alloys due to their good conductivity and strength [2], making them ideal for industrial mold applications, as their high thermal conductivity can reduce injection molding cycles by up to 80% [3]. However, these types of alloys have some processing problems due to their mechanical properties, such as high ductility, particularly for machining processes. There have been some studies about the processing of these alloys for injection mold applications, primarily directed at the electrical discharge machining of these copper-based alloys, as this process proves very useful in producing mold cavities [4]. This process is suitable for the machining of high-strength and high ductility alloys, as it does not cause any distortion during machining. However, this process is quite time-consuming as it has a very slow material removal rate and has high energy consumption [5, 6]. Therefore, it would be quite useful to employ other types of processes in the production of molds and mold inserts, made from these copper-based alloys, especially copper-beryllium. Machining processes are a viable option for the fabrication of these parts; however, there is little research conducted in this area, especially directed at machining optimization of these alloys and at the study of the wear behavior of tools applied in the machining of copper-beryllium and copper-based alloys. Understanding the wear behavior of cutting tools is quite beneficial as it provides information on the machinability of materials, and insights on what strategies to use, the best tool types, and even the most indicated tool coatings to machine a certain material [7; 8]. By evaluating the wear mechanisms and machining performance of certain tools, providing knowledge on how wear is developed throughout the cutting process, the optimization of the machining process of a certain material becomes possible [9]; this is particularly useful when considering hard-to-machine materials, such as nickel-based alloys [10; 11]. These studies offer insights on optimal machining parameters and the wear mode that tools undergo [12], enabling the selection of more adequate machining strategies, the development of new tools, or even application of the correct cooling method [13]. Studies such as these are also quite beneficial when it comes to choosing the right type of coating for a machining application, as they provide knowledge that is invaluable to produce new designs for tools and coatings [14]. Regarding machining optimization, there are a number of numerical and simulation methods that have proven useful in this regard; for example, using the Taguchi method to optimize certain machining parameters to obtain a better desired result, such as improving material removal rate [15], surface roughness [16; 17], and even tool wear. These studies offer insight on the optimal machining parameters, even relating coating thickness and structure to the process' outputs [18; 19]. Other numerical methods rely on simulations, for example, the finite element analysis, offering predictions on the machining outputs and enabling further optimization, especially if paired with other optimization methods, such as the Taguchi method or grey relational analysis [20]. Tool coatings have proven to be quite an improvement in the machining process, especially in turning [21] and milling processes [22]; however, these can be applied to a wide variety of other metal-cutting processes, such as tapping, where the use of hard-coatings has provided a viable solution for tapping hard-to-machine materials by essentially improving tool life and cutting behavior [23; 24].