Papers by Keyword: Hard Turning

Abstract: Ceramic tools are a feasible solution for machining hard steels due to their excellent performance in high-temperature environments, which improves productivity. However, the high cutting speeds achieved with ceramic tools can generate cutting temperatures so high that they damage the surface roughness of the component. Therefore, this study aims to analyze the influence of different texturing inclinations on the final roughness of the component and the cutting forces during cutting on Al₂O₃ with TiC for the turning of 1.2990 cold work tool steel. The experimental setup involved testing five different texture grooves inclinations on the rake face of CNGA 120408 inserts, with a recommended cutting speed of 180 m/min, feed of 0.15 mm/rev, and a depth of cut of 0.5 mm. The tests were carried out in dry conditions. Results showed that the textured tools produced lower cutting forces (8%) and better surface roughness (improvement of 16% for R_a and 18% for R_z) than the reference tool without texture. Therefore, texturing inclinations can be used to mitigate the impact of high cutting speeds on the component during ceramic tool machining.

Abstract: At present, grinding mode is used for the finishing process of large cylindrical roller bearing flanges. However, because of low efficiency, large consumption of grinding wheel and grinding fluid, high costs, serious pollution of cutting waste fluid, and more importantly, easy to generate grinding burns and cracks defects, grinding machining has become a technical problem that troubles the economic and effective processing of large bearing ring flanges in the bearing industry. Therefore, the research on the hard turning technology for the finishing process of large cylindrical roller bearing flanges is carried out in the paper. The experiment investigations have shown that the finishing quality of large cylindrical roller bearing ring flanges can be better and more economically guaranteed by hard turning process.

Abstract: Enhanced tool life of cutting inserts are most suitable condition for higher productivity of a manufacturing industry. Several methods are found and employed for higher tool life of cutting inserts among which cryogenic treatment is considered as the most significant method but no adequate researches have been found concerning the impact of cryogenic treatment on cermet inserts especially in hard turning operation. Hence, in the current experimental investigation, the comparative assessment of various responses such as flank wear, crater wear, chip morphology, and chip compression ratio were carried out during machining of hardened steel with both untreated and cryo-treated cermet inserts under dry cutting condition. Wear on the rake faces and flank faces were studied using advanced optical microscope, while chip morphology was studied using SEM. The experimental result demonstrated that the uncoated deep cryotreated with tempered cermet insert delivered better results in comparison to other cermet inserts. Deep cryogenically treated with tempered insert was found to be more suitable during machining of hardened steel because of the enhancement of wear resistance, micro hardness and toughness.

Abstract: Turning of hardened alloy steel (Hard turning) is a replacement for grinding operation. The heat generation and temperature during hard turning at the cutting zone and due to the friction at tool-chip-workpiece interface are significant parameters which influence chip formation mechanism, tool wear, tool life, surface integrity and hence the machining quality. Cutting fluid performs key role in metal cutting due to its cooling and lubrication action. Flood cooling is a common method of cutting fluid application, in which large quantity of cutting fluid is applied at the cutting zone. Due to environmental, health and safety concerns, the usage of cutting fluid in abundant quantity is being restricted. Most of the researchers have varied the cutting parameters like cutting speed, feed rate and depth of cut to machine different work materials with different cutting tools and studied its effects on cutting force and cutting temperature. It is thus essential to study the combine effect of cutting and jet parameters in machining. This research article focusses on study and optimization of cutting and jet parameters on tool-chip interface temperature and cutting forces during turning hardened alloy steel AISI 4140 steel of 50 HRC using Finite Element Analysis and Taguchi’s Technique. Three levels of cutting speed, feed rate, depth of cut, jet angle and jet velocity are chosen. A suitable L27 Orthogonal array is selected based on Taguchi’s Design of Experiments (DoE) and the output quality characteristics such as tool-chip interface temperature and cutting forces are analyzed by Signal-to-Noise (S/N) ratio. Analysis of Variance is performed to determine the most contributing factor, which shows that the feed and depth of cut are the most prominent contributing parameter followed by cutting speed, jet impingement angle and jet velocity.

Abstract: In the present work hard turning of AISI 52100 steel has been performed using Polycrystalline cubic boron nitride (PCBN) tools. The input parameters considered are cutting speed, feed, depth of cut, nose radius and negative rake angle and the measured responses are machining force and workpiece surface temperature. Experiments are planned as per Central Composite Design (CCD) of Response Surface Methodology (RSM). The effect of input parameters and their interactions are discussed with main effects plot. Further, the multi-objective optimization scheme is proposed by adopting Grey Relational Analysis (GRA) coupled with Principle Component Analysis (PCA). Results demonstrated that speed is the most significant factor affecting the responses followed by negative rake angle, feed, depth of cut, and nose radius. The optimum cutting parameters obtained are cutting speed 1000 rpm, feed 0.02 mm/rev, depth of cut 0.5 mm, Nose radius 1 mm and Negative rake angle 5^o.

Abstract: This work investigated the influences of cutting speed and feed rate on surface roughness in hard turning of AISI 4140 chromium molybdenum steel bar using mixed ceramic inserts Al₂O₃+TiC under dry condition for automotive industry applications. Turning experiments were conducted by varying cutting speed ranging from 150 to 220 m/min and feed rate ranging from 0.06 to 1 mm/rev. General factorial design was used to analyze the data set of surface roughness and determine statistically significant process factors based on analysis of variance results. The results showed that average surface roughness was significantly affected by feed rate and interaction between cutting speed and feed rate at the level of significance of 0.05. An optimal operating condition for hard turning of AISI 4140 with the ceramic cutting tool that produced a minimum machined surface roughness was obtained at cutting speed of 220 m/min and 0.06 mm/rev.

Abstract: The present work is aimed to investigate the effect of the turning parameters on the surface roughness produced during hard turning of AISI 52100 bearing steel with PCBN cutting tools. The experiments are devised using Taguchi L₂₇ orthogonal array and analysis is carried out using MINITAB 14 software. The influence of individual parameters is discussed with main effects plot and the combined parametric effect is presented with interaction effects plot. From the results it is observed that speed and nose radius has a great influence on surface roughness. The interaction effect is significant for speed and feed combination.

Abstract: There is a difference in machining by the cutting tool with defined geometry and undefined geometry. That is one of the reasons of implementation of hard turning into the machining process. In current manufacturing processes is hard turning many times used as a fine finish operation. It has many advantages – machining by single point cutting tool, high productivity, flexibility, ability to produce parts with complex shapes at one clamping. Very important is to solve machined surface quality. There is a possibility to use wiper geometry in hard turning process to achieve 3 – 4 times lower surface roughness values. Cutting parameters influence cutting process as well as cutting tool geometry. It is necessary to take into consideration cutting force components as well. Issue of the use of wiper geometry has been still insufficiently researched.

Abstract: Polycrystalline Cubic Boron Nitride (PCBN) tool is suitable for cutting powder metallurgy valve seat, which has high hardness and contains hard particles. By hard dry cutting different materials of powder metallurgy valve seat, the results show that: tool life when cutting melting copper powder metallurgy valve seat is longer; breakage failure is the main failure forms of tool and wear mechanism contains hard spots scratches, adhesive wear, diffusion wear and oxidation wear.

Abstract: Experimental research and modeling in the field of turning hardened bearing steel with hardness of 62 HRC using TiN coated mixed oxide ceramic inserts is presented. The main objective of the article is investigation the relationship between cutting parameters (cutting speed and feed rate) and output machining variables (surface roughness and cutting force components) through the response surface methodology (RSM). The mathematical model of the effect of process parameters on the cutting force components and surface roughness is presented. Moreover, the influence of TiN coating on above mentioned variables was monitored. The design of experiment according to Taguchi L9 orthogonal matrix (3²) was applied for trials. Pearson´s correlation matrix was used to examine the dependence between the factors (f, v_c) and the machining variables (surface roughness and cutting force components). The results show how much surface roughness and cutting force components is influenced by cutting speed and feed in hard turning with coated ceramics.