A Study of Chip Formation Feedrates of Various Steels in Low-Speed Milling Process

Sekerakova

et al. 2019

In today's unmanned productions systems, it is very important that the manufacturing processes are carried out efficiently and smoothly. Therefore, controlling chip formation becomes an essential issue to be dealt with. It can be said that the material removal from a workpiece using machining is based on the degradation of material cohesion made in a controlled manner. The aim of the study was to understand the chip formation mechanisms that can, during uncontrolled processes, result in the formation and propagation of microcracks on the machined surface and, as such, cause failure of a component during its operation. This article addresses some aspects of chip formation in the orthogonal and oblique slow-rate machining of EN 16MnCr5 steel. In order to avoid chip root deformation and its thermal influence on sample acquisition, that could cause the changes in the microstructure of material, a new reliable method for sample acquisition has been developed in this research. The results of the experiments have been statistically processed. The obtained dependencies have uncovered how the cutting tool geometry and cutting conditions influence a chip shape, temperature in cutting area, or microhardness according to Vickers in the area of shear angle.

“…The chip characteristics during the milling process by varying the feed rates and the types of materials used were investigated by Prasetyo [24].…”

Section: State Of the Artmentioning

confidence: 99%

Section: Temperature Measuringmentioning

confidence: 99%

Comparative Study of Chip Formation in Orthogonal and Oblique Slow-Rate Machining of EN 16MnCr5 Steel

Sekerakova

et al. 2019

“…Along with an evolution of new materials that should be machined and continual cutting tools improvements, the topic of chip formation and its morphology is still relevant, so many researchers are presently addressing this issue. Prasetyo and Tauviqirrahman [28] developed more comprehensive models by using a power-law flow stress equation, whose coefficients are dependent on strain rate and temperature. These effects were combined using the concept of velocity-modified temperature, and it was suggested that the flow stress for a particular material at a given strain can be assumed to be a unique function of this parameter.…”

Section: State Of the Artmentioning

confidence: 99%

Research on Chip Shear Angle and Built-Up Edge of Slow-Rate Machining EN C45 and EN 16MnCr5 Steels

Sekerakova

et al. 2019

One of the phenomena that accompanies metal cutting is extensive plastic deformation and fracture. The excess material is plastically deformed, fractured, and removed from the workpiece in the form of chips, the formation of which depends on the type of crack and their propagation. Even in case of the so-called 'continuous' chip formation there still has to be a fracture, as the cutting process involves the separation of a chip from the workpiece. Controlling the chip separation and its patterning in a suitable form is the most important problem of the current industrial processes, which should be highly automated to achieve maximal production efficiency. The article deals with the chip root evaluation of two EN C45 and EN 16MnCr5 steels, focusing on the shear angle measuring and built-up edge observation as important factors influencing the machining process, because a repeated formation and dislodgement of built-up edge unfavorably affects changes in the rake angle, causing fluctuation in cutting forces, and thus inducing vibration, which is harmful to the cutting tool. Consequently, this leads to surface finish deterioration. The planing was selected as a slow-rate machining operation, within which orthogonal and oblique cutting has been used for the comparative chips' root study. The planned experiment was implemented at three levels (lower, basic, and upper) for the test preparation and the statistical method, and regression function was used for the data evaluation. The mutual connections among the four considered factors (cutting speed, cutting depth, tool cutting edge inclination, and rake angle) and investigated by the shear angle were plotted in the form of graphical dependencies. Finally, chips obtained from both steels types and within both cutting methods were systematically processed from the microscopic (chip root) and macroscopic (chip pattern) points of view.Metals 2019, 9, 956 2 of 27 of a machined surface are in many cases not achievable by mechanical working or casting processes, because the surfaces of the parts are adversely affected. This is why machining is needed.[3] Controlling the chip separation and its patterning in a suitable form is the most important problem of the current industrial processes, which should be highly automated to achieve maximal production efficiency.One of the phenomena that accompanies metal cutting is extensive plastic deformation and fracture. The excess material is plastically deformed, fractured, and removed from the workpiece in the form of chips, the formation of which depends on the type of crack and their propagation. Even in the case of so-called 'continuous' chip formation there still has to be a fracture, as the cutting process involves the separation of a chip from the workpiece. Chips at the machining are formed due to tearing and shearing, the workpiece material adjacent to the tool face is compressed and a crack runs ahead of the cutting tool and towards the body of the workpiece. Cutting takes place intermittently and there is no movement of the w...

“…Planing is a cutting process in which the formed chip is visible to the eye, whereas in broaching, the chip generation process is hidden and invisible to the naked eye. Therefore, it is possible to monitor the development of the temperature field in the area of chip generation during planing with a temperature measuring device by laser aiming and thus providing an approximate idea of the temperature generated not only during cutting but also during broaching [1,2].…”

Section: Introductionmentioning

confidence: 99%

Effect of Machining Conditions on Temperature and Vickers Microhardness of Chips during Planing

Vašina

et al. 2022

For the machining of long and narrow surfaces and when processing multiple pieces, planing technology is used, the productivity of which can be higher than that of milling, although it is relatively slow machining. The article aims to study the degree of influence of the geometry of the tool (the angle of cutting-edge inclination and the angle of the tool-orthogonal rake), as well as the cutting conditions (cutting depth and cutting speed) on the chip characteristics (temperature and microhardness) in orthogonal and oblique slow-rate machining of steel 1.0503 (EN C45). The experiments were carried out on specially prepared workpieces designed for immediate stopping of machining. The results of the experiments were statistically processed, and behavioural models were created for temperature and Vickers microhardness of chips for individual combinations of factors. The obtained dependencies revealed how the geometry of the cutting tool and the cutting conditions affect the temperature and microhardness in the cutting area and at the same time allowed the best conditions for both orthogonal and oblique machining to be set up.