## 1 Introduction  
The transport sector is one of the main contributors to environmental pollution, second only to the energy sector. Growing concern for the environment and strict pollution control regulations have forced transport manufacturers to develop materials and manufacturing technologies to reduce pollution [1]. In this context, composite materials with excellent properties/weight ratio have made it possible for vehicles to reduce their weight and, thus, their consumption and emissions. Composite materials have long been generally used in the transport sector as substitutes for more traditional metal materials such as steel. Therefore, 21% of the general consumption of these materials is precisely for transport, mainly by air and land. Furthermore, the general trend is for the consumption of these materials to grow by more than 8% by 2025 [1]. The most commonly used compounds are polymeric matrix materials, such as Carbon-Fiber-Reinforced Polymer (CFRP) or Glass-Fiber-Reinforced Polymer (GFRP). However, in the transportation industry, a significant growth in the consumption of metal matrix composite (MMC) is expected because they offer important characteristics that cannot be obtained by other compounds. This growth is estimated to be around 30% [2]. For example, in a sector such as the automotive industry, polymer matrix composite materials are the most used and will continue to be so in the coming years. However, the growth in percentage of MMCs is expected to double by 2025 [3]. This is mainly due to the search for lighter alternatives to conventional metallic materials used in critical structural areas and in the powertrain to reduce consumption. Therefore, it is expected that while the outer areas will be produced with CFRP, the structural areas of the chassis will be produced with MCC [4]. The other sectors linked to the transport industry are following the same trend, since by adding reinforcements to a metal matrix it is possible to obtain a material 30%-40% more rigid than the matrix material. Thus, in addition to the improvement of mechanical properties, other properties such as high temperature resistance, fire resistance, control of thermal and electrical conductivity, or improved radiation resistance are achieved [1]. Therefore, it is an ideal material for industries that require lightweight materials with excellent properties. On the other hand, there are many types of MMC depending on the matrix and the reinforcement. The most interesting industrial MMCs contain an aluminium matrix [4]. Their demand with respect to the other MMCs is more than 30%, being also the most consumed by the transport industry [5]. The reinforcements are usually ceramic and discontinuous, in the form of particles or short fibers. The high configuration capacity of polymeric composite materials is also transferable to the MMCs, where it is possible to control the quantity and type of reinforcements in order to design their mechanical and thermal properties [6]. These excellent characteristics are responsible for the difficulties that arise during the shaping of these materials in processes such as machining that attempt to adjust the part to the final geometry [6]. The conventional machining of these materials is tremendously complex due to the abrasive conditions of the material that lead in relatively short times to the deterioration of the tool. This was the case in the study by [PERSON] et al. [7] where, in spite of using tools with Poly-Crystalline Diamond (PCD), the result of the drilling process was not adequate due to the rapid deterioration of the tool. Despite this, the roughness (Ra) obtained was about 0.8 \(\upmu\)m. Something similar happened to [PERSON] et al. [8], where in the turning process of an Al-SiC MMC, tools with advanced coatings such as microcrystalline diamond (MCD) or nanocrystalline diamond (NCD) had a life of about two minutes, and others with simpler coatings, like TiAlN, suffered catastrophic breakage.