## 1 Introduction  
Given their high performance under severe working conditions, via mechanical and thermal stresses and harsh chemical environments [1; 2], superalloys and advanced materials have been widely used in the manufacturing of components for jet engines [2], turbochargers [3] and aerospace [4] applications. Nevertheless, these materials display difficult machinability characteristics [5; 6] due to their low thermal diffusivity [2], high strain hardening [7], high chemical reactivity [8], carbide precipitation in grain boundaries [1] and high ductility [9]. Chief among these machining attributes, the high ductility of machined workpieces ordinarily leads to the formation of long continuous chips during the machining process, which negatively affects the safety, efficiency and continuity of the machining operation [10]. An appropriately controlled machining process enables high productivity and minimizes costs of energy, materials, and tools [11]. This necessitates restrictive cutting conditions to be identified and rigorously applied [11; 12]. In addition, an appropriate design of a cutting tool is essential to achieve an effective chipping operation and to extend tool life [13; 14]. However, chip evacuation is a recurrent problem that needs addressing with machining ductile and soft materials, especially with the formation of continuous chips [10; 15; 16]. Discontinuous and fragmented chips are easier to control as continuous chips can wrap around the workpiece and/or the cutting tool and clog the cutting zone, which negatively affects the cutting process. Such chips can scratch the newly machined surface, detract from its quality and increase tool wear/breakage thereby decreasing tool life [17; 18]. This results in a higher number of production stops and, therefore, in a dramatic increase of production time. Thus, the chip formation process and chip control using combined cryogenic and minimum quantity lubrication [19; 20], applying cryogenic lubrication [7; 21], high pressure coolant [2; 11] ultrasonic-assisted vibration [15; 17], optimization of the processing parameters [10; 22; 23; 24], and chip breakers [10; 14; 16] as well as their limitations [25], have been widely studied, both experimentally and by means of simulation. It is widely accepted that the contribution of chip breakers in enhancing the chip fragmentation process is significant. Chip breakers prolong tool service life and enhance obtainable surface finishing of the component, particularly when it comes to cutting ductile materials [16]. Generally, there are a wide range of carbide-tools with an enormous variety of chip breaker types and shapes commercially available. However, to the best of the authors' knowledge, this is not the case for polycrystalline diamond (PCD) tools, where there is a gap in the market to offer reliable PCD inserts with chip breakers [25]. Due to its high hardness and high abrasive resistance, PCD inserts are widely used for the high-quality machining of non-ferrous metals such as aluminum alloys [26; 27]. Given that aluminum alloys are ductile materials, the machining processes of such materials are associated with the generation of continuous chips that require dependable chip control. In this context, there has been an increasing demand for PCD inserts with chip breakers to satisfy the ongoing requirements of modern machining applications. Recently, there have been trials by such tool manufacturers as Mitsubishi, Lach Diamond, and others to integrate non-conventional technologies in their production processes in order to introduce chip-breaker geometries in their PCD inserts [28; 29]. However, these implants are for standard and general-purpose inserts only, and there are no similar applications for special or custom tools. When tailoring chip breakers for machining ductile materials, it is important to consider the different breaking mechanisms of the chips generated, founded on the processed material, process parameters and cutting tool geometry.