Papers by Keyword: Cutting Tool

Abstract: Tool wear is an important problem when cutting hard-to-cut materials such as stainless steel and nickel alloys. This unignorable disadvantage is caused by the diffusion of dissociated carbon atoms to the surface layer of the tool tip during the cutting process, and this has been confirmed by SEM/EDS analysis of worn tool tips. In this study, a novel cutting method is proposed in which chemically activated H₂O molecules are introduced to the cutting tool tip in order to prevent tool wear by removing dissociated carbon atoms on the surface layer of the tool tip. In cutting experiments, stainless steel X5CrNi 18-10 (JIS SUS304), a cemented carbide tool tip, cutting oil, steam, and Ar plasma were used. Ar plasma was used for raising the steam temperature around the tool tip and chemically activating H₂O molecules. From the results, the dissociated carbon and constituted knife edge were mostly removed by H₂O steam and cutting oil without Ar plasma. However, in some cases using Ar plasma, the workpiece melted and tightly adhered to the cutting face of the tool tip. This suggests that the H₂O steam temperature should be suitably controlled so as to remove carbon atoms effectively from the cutting face of the tool tip.

Abstract: Direct diamond deposition on a steel surface has been considered very difficult. Recently, we found that high-quality diamond films can be deposited on the surface of stainless-steel X5CrNi 18-10 by drilling multiple regularly arranged pits without interlayers or seeding. The following two hypotheses (A) and (B) can be considered as the reason why a high-quality diamond film can be deposited: (A) unoxidized Cr and Ni exposed to the stainless-steel X5CrNi 18-10 surface prevent carbon diffusion into interior of the stainless-steel, resulting diamond core generation, (B) Surface geometry with regular roughness contributes to stress relaxation and delamination prevention. In the present study, those hypotheses have been examined by quantum chemistry calculation and experimental. For the quantum chemistry calculation, energy barrier and kinetic energy for a carbon atom intrudes into a model cluster has been calculated with an ab-initio computational chemistry software package, Gaussian. The calculation result has supported hypothesis (A). For the experiment, X5CrNi 18-10 stainless-steel substrates with different surface characteristics are prepared by using various mechanical machining methods and used in the direct deposition process for diamond with in-liquid plasma CVD. The experimental result has supported both hypothesis (A) and (B).

Abstract: Additive Manufacturing (AM) represents a technology that provides access to part designs that are impossible or very difficult to achieve by any other manufacturing process. In addition to this consideration, the possibility of customization, and consequently, the almost immediate adaptation of dimensions and geometries makes the AM an exceptional alternative in the manufacture of prototypes. From the experience in the teaching of subjects in the Manufacturing Processes Engineering Area, it has been in different aspects of them that a special difficulty has been detected by the students in the spatial visualization of the concepts. A case of this, of special relevance, is that of the main cutting angles in a machining tool (with two cutting edges, main and secondary). In this work, a proposal for teaching innovation is proposed through the materialization of a removable model made with AM of a cutting tool in which different elements can be broken down, giving rise to the different angles indicated above. The students can operate with it, observing the angle of interest. The possibility of manufacturing with different polymeric, composite or metallic materials, of making modifications to the original designs to alter the contemplated angles and create new model configurations, the precise adjustment of the different pieces due to the non-appearance of a gap between them, the use of a wide range of colors for each piece or set of them, and changes in scale and so on, offer the possibility of expanding this work to any other type of cutting tools.

Abstract: The article considers the issues of assuring the quality of the surfaces of machine parts by applying a preliminary local thermal impact before their edge cutting machining. In the zone of application of local thermal impact, a zone of metastable structure with respect to the material of the workpiece to be treated occurs. When the cutting plane intersects with the local thermal application line, the formed flow chip is segmented. The created graphs allow assigning of local thermal modes to the surface of the workpiece before edge cutting machining. Application of preliminary local thermal impact will assure the specified quality of the surface of the treated workpiece at semi-finishing and finishing edge cutting machining modes and stable segmentation of the flow chip.

Abstract: PVD (physical vapor deposition) hard coatings are widely used and common in manufacturing technologies, for the use as wear and oxidation protection of tools and components. Therefore, many specialized hard coatings systems have been developed until now. Nevertheless, there is a demand to improve the functionality of PVD hard coatings, i.e. due to a self-lubricating effect through tribological activation. According to the current state of research, solid lubricants with lattice layer structure and oxidic solid lubricants are particularly suitable for this purpose. This work gives an overview on the functional mechanisms as well as required environmental conditions and activation mechanisms of transition metal dichalcogenides (TMD) and Magnéli-phases.

Abstract: This paper investigated the performance of ZTA cutting tool with the addition of different particle size of MgO additive. Therefore, the objective of this research is to compare the effects of machining parameters on tool wears of ZTA cutting tools added with micro and nanoparticle of MgO. The experiments were conducted using BridgePort-Romi Powerpath CNC machine using a tool holder Sandvik Coromant (CoroTurn CCLNR 164D-4) to hold the cutting tools properly. The parameters are set up as cutting speeds used between range 354 to 472 m/min, feed rate from 0.1 to 0.5 mm/rev with a constant depth of cut of 0.2 mm. Three types of wear were analyzed which are flank wear, crater wear and tool chipping. Flank wear and crater wear images captured using measuring microscope (NIKON MM-400/L) and the crater wear areas are analyzed using MatLab programming software. Tool chipping is observed via SEM (JEOL JSM-5600). The experimental result shows that flank wear and crater wear increase when cutting speed and feed rate increase. ZMN cutting tool shows lower value of flank wear at 0.143 mm and 3.741 mm² for crater wear than ZMM, 0.321 mm and 3.808 mm² respectively. On the contrary, cutting speed did not affect the tool chipping severely as feed rate. Moreover, ZMN also shows that the tool breakage occurred severely than ZMM due to the high load on the tool nose.

Abstract: Metal cutting is one of the most important machining processes in manufacturing industry. Thorough understanding of metal cutting process facilitates the optimization in selection of cutting tools and machining parameters. There are several methods used for studying phenomena in metal cutting process. Using a quick-top device is an efficient technique for investigation cutting process in which cutting action is stopped so suddenly that the “froze” specimen called the chip root honestly depicts what happened during cutting action. Design strategies of a quick-stop are accelerating cutting tool away from the workpiece or decelerating the workpiece remaining in engagement with the tool. Operation of a quick-stop device can be either mechanically or by explosive. Quick-stop devices can be utilized for various types of machining processes such as: turning, milling, drilling. This paper described the analysis, fabrication, and testing of a quick-stop device which is used for researching on chip formation in hard turning. This device has simple and safe operation which utilizes spring forces to retract the tool from workpiece during cutting. The results of performance at cutting speed of 283 m/min show that the separation distance is quite small, less than 0.2mm so that the deformations on the root chip are close to that while actual machining process. This indicates that the device has satisfied the requirements of an equipment for studying on chip formation.

Abstract: The article describes the influence of the acidity degree of oxide compounds formed on contact surfaces of carbide cutting tools type P on their wear resistance when cutting materials causing intensive diffusion wear. It was found out that when the acidity degree of surface film oxides formed on the cutting wedge contact surfaces decreases, wear resistance of cutting tools tends to grow.

Abstract: In the paper it is pointed out that machining of titanium alloys is the most difficult problem in metal cutting. The leading world companies are dealing with this problem, as titanium alloys are the basis of the aerospace industry. In the paper high-speed cutters with wavelike teeth edges used for titanium alloys processing are investigated. Every subsequent tooth is displaced at half-space distance. This reduces power load on the hardening of the machined surface. On the basis of power and wear-resistance studies, the advantage of wavy milling cutters in comparison with standard ones is established; it is proved that wavy cutters have a lower specific power load, greater wear resistance and less surface hardening.

Abstract: In this article comparison of two methods of the cutting temperature calculation is made: according to the theory of A.N. Reznikov and the theory of S.S. Silin. The values of the cutting temperature calculated according to both methods are compared to the experimental data provided by various authors. It is determined that both methods can be used for cutting temperature calculation, however they have some limitations. In particular, when making the calculations according to S.S Silin’s theory the parameter, characterizing the degree of plastic deformation of the metal machined should be not less than 0.4. When calculating the cutting temperature by Reznikov’s theory it is necessary to take into account the nature of the physical processes of cutting.