# Application of 3D Imaging for Analyzing the Chip Groove Shapes of Cutting Inserts
## 1 Introduction  
One of the most commonly used subtractive machining methods for the manufacture of machine parts is machining. It is widely used due to its ability to shape objects with complex geometries while maintaining high-dimensional accuracy and surface quality. On the other hand, material waste and long operating cycles are cited as machining disadvantages. The basis of machining is the removal of layer after layer of excess material from the workpiece in successive work passes of the cutting tool in order to obtain the desired shape of the part, dimensions, and properties characterizing the surface layer [1, 2]. The layers cut in the machining process are transformed into waste material, i.e., chips. Chips affect the surface quality of the workpiece, the manner and the course of wear of cutting tools, and the stability of the machining process. The morphology and process of chip formation are influenced by the following factors [3, 4]:  
* Properties and chemical composition of the workpiece material;
* The type and geometry of the cutting tool and the shape of the rake face;
* Accepted values of the cutting data;Physical phenomena occurring in the cutting zone, e.g., the built-up edge on the cutting edge;  
Type and degree of wear of the cutting edge;  
Method of cooling the cutting zone and type of coolant and lubricating fluid;  
The type of tool material and coatings applied to the tools. From a simplified perspective, chips can be distinguished as correct, acceptable, or unacceptable. Preferred chips are short, fine, and usually similar in shape to the letter \"C\". Long, ribbon-like, or spiral and often tangled types are unacceptable, as they can have a destructive effect on the quality of the machined surface and cause catastrophic tool wear. The acceptable form of chips can be characterized by chips that are unacceptable but with acceptable dimensions, e.g., length or diameter, while mixed chips appear when correct and unacceptable chips are produced in the cutting process at the same time [5]. With regard to the breaking mechanism, there are three types of chips: self-breaking, brittle in contact with the tool, and brittle in contact with the workpiece. Important factors influencing chip breaking are the direction of flow of the chip and its curvature. The direction of flow of the chips is a determining factor in chip breaking, as it affects both the curvature of the chips and their orientation. During cutting, the bending torque and the friction at the chip-tool interface affect the radius of the curvature of the chip. A smaller radius of the curvature of the chip results in stronger chip cracking and breaking [6]. The shaping of the rake face of cutting tools (the so-called chip groove) is intended to force the way the chip flows toward the clearance surface or the unmanned surface of the workpiece. When the chip hits an obstacle, i.e., a clearance or unmanned surface, it cracks and breaks. This results in a direct change of unacceptable chips to the correct form. Due to its function, this shape of the rake face is called a \"chip retractor\" [7]. However, the so-called \"chip breakers\" found in tool construction are most often used for the direct breaking of long, continuous chips. Studies have shown that the depth and width of the chip breaker have a significant impact on the outcome of the chip-breaking process. It was found that as the depth increases and the breaker width decreases, the chip-breaking efficiency in finishing is improved, and as the depth decreases and the width increases, the chip-breaking efficiency in roughing improves [8]. Due to the fact that the geometry of chip breakers has a positive effect on the machinability of materials, they are also used in drilling and even milling processes. In milling, the geometries of the chip breakers have no effect on cutting forces, and their use increases the curvature of the chip and significantly improves surface roughness [9]. Continuous chips, on the other hand, are problematic during drilling.