Papers by Keyword: Turning

Abstract: The physical and chemical properties of bio-titanium alloy implant surface play an important role on corrosion resistance and biological activity. New turning processes under oxygen-rich atmosphere were presented to obtain required titanium dioxide layer, which can protect implants from corrosion. The thickness of the oxidation film were observed using Auger Electronic Spectrum (AES). Then the corrosion resistance was tested in simulated body fluid by electrochemical corrosion. The results showed that the thickness of oxidation film by turning in oxygen-rich 80% was 69 nm, which was 4.6 times of that under natural conditions (15 nm). The thickness of processing surface oxidation film was increased by turning process under oxygen-rich atmosphere, indicating that this process could slow down the speed of titanium alloy corrosion and significantly improve the corrosion resistance.

Abstract: Turning is one of the fundamental machining operations and its process parameters leads to better machining performance. The economic benefit of turning operation is providing components with appropriate dimensional accuracy. In this work, the effects of process parameters on dimensional accuracy (circularity and cylindricity) parameters are analyzed in turning of EN25 steel. The process parameters considered are cutting speed, feed rate and depth of cut in order to minimize circularity and cylindricity. The result revealed that the minimum dimensional accuracy error values such as circularity and cylindricity are obtained in the combination of higher value of cutting speed and lower value of feed rate and depth of cut. This analysis is used to meet the machined work piece within the tolerance limit and improve the quality criteria.

Abstract: In fast spreading hard turning occasionally a so-called white layer appears on the machined surface, which is mostly harmful. The formation of white layers and their composition, structure and thickness were investigated in the turning of the inner cylindrical surface of gear wheels made from 20MnCr5 case hardened steel, in order to identify to what extent the technological parameters of turning influence the white layer formation. On the basis of the measurement results it was possible to include border-line technological conditions in an empirical formula with which white layer formation can be avoided.

Abstract: The article deals with finishing parts manufactured by means of PolyJet 3D Printing additive technology using Objet500 Connex made of polymers with trade names "Vero White Plus" and "Digital ABS". A turning technology on a CNC turning lathe was used for finishing the surface of the parts. The goal of this article is to find optimal cutting conditions for finishing operations by turning of these materials with regard to the best surface quality possible even during interrupted cutting.

Abstract: For an accepted physical model with allowance of cutting “on a trace” phenomena, the initial mathematical model for want of processing non-rigid shafts is considered. In this model the improper rigidities of an elastic system are taken into account. In particular, pliability of a technological system on coordinate X in relation to cutting forces component on Y coordinate. Considered the individual models of dynamic system of turning machines for want of small rigidity shafts processing with management on the channel of additional managing force effects, which with a sufficient degree of an exactitude can be used in engineering accounts.

Abstract: This paper presents a study of the influence of cutting conditions (cutting velocity, feed, cutting depth and lubrication) on turning TC11 (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si) titanium alloy. Taguchi methodology design was adopt for carrying out experiments. Turning process parameters such as cutting speed, feed rate and depth of cut were varied to study their effect on process responses such as cutting force (Ft), surface roughness (Ra) and temperature on cutting zones (T). Minimum quantity lubrication (MQL) technology was adopt to increase the lubricating and cooling effect. Meanwhile, CVD diamond coating was deposited on the cemented carbide insert to reduce its friction with workpiece and increase its wear resistance. From the analysis of orthogonal tests, depth of cut contributes the most for the main cutting force and cutting temperature, while feed rate had the most significant effect on surface roughness on the workpiece. MQL can reduce the cutting temperature at the cutting zones, especially for the uncoated cutting inserts whose temperature decreases by an average of 60~80°C. The cutting force, surface roughness and cutting temperature of CVD diamond coated inserts were all higher than those of uncoated tools, especially with MQL lubrication. Considering the cutting efficiency and cost, the optimal parameters in the turning process of TC11 for minimizing the cutting force, surface roughness and cutting temperature are obtained as Vc=115m/min, f=0.08mm, a_p=0.5mm under MQL lubricating with uncoated cemented carbide as the cutting tool.

Abstract: Slender shaft is of high slenderness ratio and bad rigidity. The factors, for example, cutting force, cutting heat, vibration and so on, which are produced in the processing, will affect directly the size precision of workpieces. In this research, slender shaft is 304 stainless steel bar, with length of 450mm and diameter of 10mm. In order to resolve the problem of slender shaft machining with CNC slant bed lathe not configured with the follow-rest, a self-made follow-rest was developed. With both ends clamped processing mode, it is possible to use the CNC lathe turning slender shaft. Moreover, better effect of turning of slender shaft can be attained if ultrasonic vibration cutting technology is involved. After turning process is completed, size accuracy is checked to evaluate the effect of self-made follow-rest and both ends clamped processing mode. In this study, the experimental results show that quality of the slender shaft processing has been significantly improved with the use of self-made follow-rest and both ends clamped processing mode, which has definite effects on solving the practical problems of processing.

Abstract: Turning is one amongst the most adequate and cost-effective method in manufacturing environment. To meet the difficulties of extensive competitiveness in manufacturing industry the issues of selecting best preferable methodologies, design of process, machine and equipment becomes more mind boggling as there are lots of options in view of conflicting criteria. To help these selection processes, different Multi Criterion Decision-Making (MCDM) techniques are currently accessible. In this paper, MCDM technique was performed considering hybrid approach comprehensive grey complex proportional assessment (COPRAS-G) to identify optimal parameters for important multi-performance criteria like Surface roughness, power consumption and frequency of tool vibration. The important process parameters used during turning of ASTM A36 mild steel were depth of cut, spindle speed and feed using full factorial Taguchi’s design of experiment. Finally, optimal settings of input process parameters were found as speed: 160 r.p.m., depth of cut: 0.1 mm. and feed rate: 0.08 mm/rev. This study aimed to focus the applicability of COPRAS-G as a strategic decision making tool to handle multi objective optimization problem for tuning operation.

Abstract: In this paper an experiment was carried out to examine the magnitude of differences among cutting fluids and their influence on lathe power consumption during machining. It was discovered that there is no universal cutting fluid. An attempt was made to study the possibility of Artificial Neural Network to model the behavior function for all cutting fluids. This could be used as a foundation for later database building where it would be possible to predict how certain cutting fluid will behave in a specific machining parameter combination.

Abstract: The paper presents the results of turning tests of Ti6Al4V alloy with a sintered carbide tool. For selected sets of cutting data, two kinds of coolant supply were compared. Conventional coolant supply with the pressure of 7 bar was compared with HPC (High - Pressure Coolant) system working with the pressure of 70 bar. The tests revealed the fact that HPC system is useful for small values of feed taking into account chip form. Photographs of chips and their form analysis are presented. The results of tests performed by Sandvik Coromant concerning turning stainless steel were compared and discussed.