Papers by Keyword: Turning

Abstract: Because of effective machining operations with a very small amount of cutting fluids, near-dry machining attracts increasing attentions for environmental and economical benefits. MQL machining has so far been recognized as the most representative near-dry method and it is highly successful in machining of most ordinary steels. Recent concern for environmentally friendly manufacturing further encourages the attempts at applying near-dry operations to machining of difficult-to-cut materials. Since titanium alloys are typical difficult-to-cut materials, this paper investigates the cutting performance of various near-dry methods in turning of a titanium alloy from the view point of elongating the tool life. Those near-dry operations include supply methods of regular MQL mist, coolant mist and hybrid mists, where the coolant mist is atomized water-soluble cutting fluid and hybrid mists are the mixture of MQL and coolant mists. The regular MQL operation provided longer tool life than that of dry machining. In addition, compared with MQL machining, the hybrid mist operations could further extend tool life and, in particular, the single coolant mist operations demonstrated the possibility of making the tool life longer than that of ordinary wet machining with flood cutting fluid supply.

Abstract: The present work develops a learning methododology based on experiments related to the cutting temperature concept in turning processes. This proposal allows students to measure the temperature actually reached during a typical turning operation with a semi-automatic lathe. Temperature data are collected by a thermographic camera, which implies acquiring competences in this technique. The different tests involved in the practical experiment are defined for various cutting speeds and feed rates, and for a constant depth of cut. Two different materials are considered to point out the influence of turning parameters on cutting temperature.

Abstract: This study examined the influence of cutting speed, cutting fluid, and pre-impregnated carbon fiber orientation on tool wear and finished surface roughness during turning of carbon fiber reinforced plastic (CFRP) pipes. In the dry cutting process, the tool wear decreased as the cutting speed was increased. An average cutting speed of 92 m/min or higher was found to be acceptable with respect to tool wear. The use of mineral oil resulted in a reduction of tool wear when compared with that in the case of dry cutting. The tool wear with water was lower than that with mineral oil. It was assumed that cooling by water was more effective than lubrication by mineral oil. The results clearly indicated that the tool wear and the finished surface roughness were affected by the carbon fiber orientation.

Abstract: This paper presents the modeling of cutting performances in turning of 2017A aluminium alloy at four turning parameters: cutting speed, feed rate, depth of cut, and tool nose radius. These performances include: surface roughness, cutting forces, cutting temperature, material removal rate, cutting power, and specific cutting pressure. The experimental data were collected by conducting turning experiments on a Computer Numerically Controlled lathe and by measuring the cutting performances with forces measuring chain, an infrared camera, and a roughness tester. The collected data were used to develop multiple regression models for the pre-cited cutting performances and investigate the effects of turning parameters and their interactions on responses. To evaluate the accuracy of the developed models, two performance criteria were used: Correlation Coefficient (R²) and Average Percentage Error (APE). It was clearly seen that the multiple regression models estimate the cutting performances with high accuracy: R²>94% and APE<7%. Therefore, this method is an effective tool for modeling the cutting performances in turning process.

Abstract: This paper details experimental results when turning Ti-6Al-4V using water-miscible vegetable oil-based cutting fluid. The effects of coolant concentration and working conditions on tool flank wear and tool life were evaluated. L27 fractional factorial Taguchi array was employed. Tool wear (VB_B) ranged between 28.8 and 110 µm. The study concluded that a combination of VOs based cutting fluid concentration (10%), low cutting speed (58 m/min), feed rate (0.1mm/rev) and depth of cut (0.75mm) is necessary to minimise VB_B. Additionally, it is noted that tool wear was significantly affected by cutting speeds. ANOVA results showed that the cutting fluid concentration is statistically insignificant on tool flank wear. A notable increase in tool life (T_L) was recorded when a lower cutting speed was used.

Abstract: Surface finish of machined components plays a key role in their life performance. The aim of this research is to investigate the effect of different roughness parameters on high cycle fatigue behavior of Inconel718. Rotating bending fatigue tests have been performed on Inconel718 specimens with various surface roughnesses produced by turning. Height and amplitude distribution roughness parameters were investigated. Statistical analyses show that a valley material component (Mr2), as one of the amplitude distribution parameters, is the most relevant parameter for the high cycle fatigue life of machined specimens. Observations conducted at the surface of broken specimens gage length, have shown the impact of surface roughness and residual stresses on the crack propagation mode. When the roughness increases, valleys were shown to be deeper and larger, leading to a higher Mr2 value and an increase of stress concentration.

Abstract: The paper presents the results on research of machining anti-friction bushings of lever brake systems of rail transport, wherein the bushings are made of powder material based on iron and copper. Powder composition contains Fe-C-Cu with Ni and Mo content of less than 0.3%, and with reduced phosphorus content. The porosity of the bushings were in the range of 15 – 20 %. The main objective of the work was to determine the optimal machining parameters, as well as to evaluate the quality of the machined surface. The bushing were machined with cutting speed in the range of 130 – 150 m/min. To assess the quality of the machined surfaces the 3D roughness parameters were used, which allow to asses the surface roughness in more accurate details. The microstructure of the samples indicated the presence of pores onto the machined surfaces. It was found that to improve the quality of the surface it is necessary to adjust the parameters of the powder processing of parts with high porosity in the direction of their reduction. Studies of the microstructure and morphology of chips showed that the shape and structure of the chip is highly dependent on the porosity of the material and its processing conditions.

Abstract: Graphitized steels are claimed to perform excellent in machining processes. They therefore can be considered as environmental friendly alternatives to the widely used Pb-alloyed steels. Due to liquid metal embrittlement and in-situ lubrication Pb improves machinability in a narrow tool-chip interface temperature window corresponding to low machining speeds. Although graphite inclusions are also supposed to generate in-situ lubrication, the mechanism and the corresponding optimum working zone is not very clear. The present work applies a new test methodology (including in-situ tribology, analysis of material flow and chip formation, optimum working zone analysis) to investigate the effects of graphite inclusions on turning and drilling operations. A Pb-alloyed low carbon free-cutting steel and Pb-alloyed case hardening steel were used as reference steels.

Abstract: This work extent with the improvement of machining parameters in turning of SS304 austenitic stainless-steel in Computer Numerical Control (CNC) shaping machine by victimization of coated inorganic compound tools. Throughout the experiment, process parameters like Speed, Feed and Depth of Cut are used to inquire their general intent on the Surface Roughness (Ra) and Material Removal Rate (MRR) as the quality targets. 9 experimental runs supported by one factor at a Time Approach as Design of Experiment and Grey Relational Analysis (GRA) method is applied to see associate degree for optimum CNC turning parameter setting. An optimal parameter combination of the turning method is obtained by victimization of Grey Relational Analysis. By dissecting the Grey Relational Grade matrix, the degree of influence for every controllable process factor onto individual quality targets is found for the higher performance characteristics.

Abstract: Iron-based sintered materials are fabricated via the process of compacting iron powder by using die, sintering in 1100 to 1300°C, and quenching or sizing. These materials are used as variable valve system and oil pump system in automobiles. Recently, the severe requirement for complication and high precision shape of them has increased the products machined by turning and drilling. In general, it is more difficult to machine the sintered materials than the steel. However, the quantitative evaluations and the mechanisms of those are ambiguous, then there is a few suggestion for improvement of the machining. In this study, we will report the machinability of sintered materials by compare with that of steel materials, and the improvement of machinability of sintered materials.