# Prediction of Cutting Parameters of HVOF-Sprayed Stellite 6
## 1 Introduction  
Classical or conventional machining is a process of removing material in the form of chips by direct contact between the tool and workpiece. It depends what kind of machining process is used, but generally, the tool penetrates into the workpiece to a certain depth, while the workpiece or tool provide suitable motion. Tools have a specific number of cutting edges of known geometry. During machining the workpiece is subjected to shear, compression and also bending and not only the surface of the material is altered but also below it. The process of material removal puts very high demands on surface quality. The topography of the machined surface has a significant effect on its function and must be taken into account for the setup of machining conditions. The machining behaviours of materials differ from each other. The rapid evolution of material development has had a direct impact on the development of new machining technologies. High-speed machining technologies represent an effective way to increase productivity. The productivity of any such process is limited by the machinability of the material. Material properties consequently affect machining behaviour. Cobalt-chromium alloys aresome of the most difficult materials to machine [1]. The properties which make them very attractive in the industry include high strength and hardness at high temperatures and corrosion resistance. Usually, the problems with the machining of these materials concern the cutting speed and feed, as they have a very narrow recommended application range for good results. If the cutting speed is too low, the material sticks to the cutting edge, and if it is too high, abrasive wears occurs on the cutting edge. The development of Stellite played a particularly important role in metal cutting after the first use of tungsten steel and high-speed steel in the 19 th century. The Stellite alloy was invented in 1900 by American metallurgist [PERSON] as a substitute for silver In 1907, the Deloro Smelting and Refining company was founded by [PERSON] and [PERSON] in the village of Deloro (Ontario, Canada). When [PERSON] in 1912 focused on nickel-based components, [PERSON] founded the Deloro Stellite company for the production of cobalt-based alloys. There is a slight difference in the composition of the Stellite alloys. Stellite 6 is one of the most popular among them and is suitable, for example, for press forging. The higher carbon alloys (Stellite 6K and Stellite 6B) are used for abrasion, or severe galling and are more difficult to machine than lower carbon alloys. The lower carbon alloys are often used for sliding wear or cavitation. Shape and size of the carbides are dependent on the cooling rate, and an increase of carbides reduces ductility [2; 3; 4; 5; 6]. Stellite 6 is a popular alloy that has several industrial applications, therefore, machining this superalloy has been a subject of intense engineering research because of the need to determine the best machining tool to forge, cast, cut, and finished industrial products. Some surfaces are sprayed with Stellite 6, and machining such surfaces requires experience and skill in order to achieve the required results for commercial applications. Experiments have been done to identify the cutting tool surface and physio-mechanical properties that can ensure that Stellite 6 is properly machined [7; 8; 9; 10]. While such studies have yielded good results, no consensus has been reached that can point to the right type of tool to machine Stellite 6. Therefore, further research has to be done in order to ensure that the tip wear of the alloy is improved. Stellite 6 is used to build-up surfaces that are subjected to intense wear and can be used in a welded or sprayed form. Most of the recent studies have focused on the evaluation of Stellite-6 coatings with regards to the following aspects: microstructure [11; 12; 13], chemical compositions, mechanical properties, tribological characteristics [14], or residual stress distribution [15].