• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.4
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• pp.48-53
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• 2009

Inconel 718 alloy, widely used as material of aircraft engine, has a good mechanical property in high temperature, strong anti-oxidation characteristics in oxidated current over $900^{\circ}C$, and also is not easily digested in the air containing sulfur, therefore, its usage as mechanical component is expanding rapidly. Even though Inconel alloy 718 is difficult to machine, it requires highly precise processing/machining to sustain its component quality of high accuracy. In this paper, general turning operation conditions are tested to select the best cutting process condition by measuring surface roughness through implementing experiments with orthogonal array of cutting speed, feeding speed and cutting depth as processing parameters based on the Taguchi method. Optimal turning operation conditions are extracted from the proposed experimental models.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.3
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• pp.48-57
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• 1995

The feasibility of generating controller surface topographies in single-point conventional turning operations is investigated. First, a mathematical model of the surface generation process was developed. Second, in order to control the texture of the machined surface, a micro-positioning stage and the associated command generation software were designed and built. Experimental examples have shown that surface texture can be precisely controlled and is in good agrement with the theoretical predictions.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.03a
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• pp.24-33
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• 1995

The feasibility of generating controlled surface topographies in single-point conventional turning operations is investigated. First a mathematical model of the surface generation process was developed. Second in order to control the texture of the machined surface a micro-positioning stage and the associated command generation software were designed and built. Experimental examples have shown that surface texture can be precisely controlled and is in good agreement with the theoretical predictions.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.58-64
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• 2008

The cutting process of materials is accompanied with the elastic and plastic deformation due to chucking forces in the boring process of thin holes on the turning. Upon removal of chucking forces at the end of process, the original shape is remained in the plastic deformation; on the other hand, it is modified in the elastic deformation due to spring back. Fixing materials by chucks on the turning has influence on roundness because the process is conducted with unbalanced distribution load induced from the fixing of three jaws. Moreover, the amount of spring back depends on the magnitude of fixing forces. We studied the change of roundness according to fixing forces as well as the method to reduce the influence of chucking forces.

• Design & Manufacturing
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• v.11 no.1
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• pp.50-54
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• 2017

In this study, researches were conducted as follows. First, as the basic experiment, the cutting speed, feedrate, and the depth of cut were set as the process parameters, and by setting the surface roughness as the factor of measurement for each of the combinations, and the analysis about cutting tendency of the material was conducted by proceeding the turning process of Co-Cr-Mo alloy. Second, by setting the feature of the surface roughness according to the 'turning processing condition' that was confirmed in the previous experiment, and by applying the Taguchi Method, the conditions that influence the features of the surface roughness according to the 'turning processing condition' of Co-Cr-Mo was analyzed, and also by measuring the surface roughness according to each of the 'cutting conditions', the optimal processing condition was generated. As the result of analysis, it was possible to understand that the factor that mostly affects the surface roughness was the cutting speed, followed by the dept of cutting and transfer speed, and as for the optimal processing condition, it was possible to find that the cutting speed was 5,000rpm, and the depth of cut was 0.1mm, and the feedrate was 0.003mm/rev, and the value of the surface roughness at this point is $0.197{\mu}m$.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.12
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• pp.47-54
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• 2008

Hard turning process can be defined as a single-point machining process carried out on "hard" materials. The process is intended to replace or limit traditional grinding operations that are expensive, environmentally unfriendly, and inflexible. The purpose of this study is to achieve a systematic understanding of machining characteristics and the effects of machining parameters on cutting force, tool wear shape and chip formation by the outer cutting of a kind of wear resistant tungsten carbide V30. Hard turning experiments were carried out on this alloy using the PCD (Poly Crystalline Diamond), cBN (cubic Boron Nitride) and PcBN (Polycrystalline cubic Boron Nitride) cutting tools. The PcBN and the usual cBN tools were used to be compare with the PCD tool and the dry turning was carried out. The PcBN is attractive as the tool material which replaces the PCD. The tool wear width and cutting force were measured, and the worn tool and chip were observed. The difference of the tool wear mechanism among the three tool materials was investigated.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.8
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• pp.21-28
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• 1997

This paper presents the influence of the process parameters on the change in dynamic behavior of a lathe turning system. With variation of feed rate, depth of cut, direction of tool motion, cutting speed and tool location along the workpiece, the dynamic characteristics of stable cutting, chatter transition and fully developed chatter regions are demonstrated. The workpiece vibration during machining is continuously measured at different tool locations along the workpiece and quantitatively analyzed. Complex linear behavior due to change of process parameter values as well as fundamental wystem nonlinearity due to change of process configuration indicated by a tool path dependence of the locations of chatter onset and disappearance are described. Finally, the structural characteristics of the turning system which can have large and nonlinear effects on system behavior are presented.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.10
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• pp.36-43
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• 2020

A marine turning gear is the main auxiliary machine that enables the disassembly of and maintenance on the main engines. In this study, a marine turning gear based on a helical planetary reducer was developed through analysis of a marine turning gear based on a spur planetary reducer. Nonlinear numerical analysis was performed to determine the ideal contact ratio between the sun gear and the idle gear. Based on this, the surface durability, tooth bending strength, and contact ratio were calculated. In addition, the helix direction was selected to utilize the existing bearings. Gears were manufactured based on the helical gear design values, and the turning gear was evaluated using the FTA standards of MAN Co. Ltd. As a result, a lifetime of 3,000 to 5,000 hours was verified, the maximum torque measured was 105kNm, and the efficiency was measured to be 87.4%.

• Journal of Mechanical Science and Technology
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• v.18 no.12
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• pp.2182-2189
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• 2004

In the recent years, environmentally conscious design and manufacturing technologies have attracted considerable attention. The coolants, lubricants, solvents, metallic chips and discarded tools from manufacturing operations will harm our environment and the earth's ecosystem. In the present work, the Tukey method of multiple comparisons is used to select the minimum level of coolant required in a turning process. The amount of coolant is varied in 270 designed experiments and the parameters cutting temperature, surface roughness, and specific cutting energy are carefully evaluated. The effects of coolant mix ratio as well as the amount of coolant on the turning process are studied in the present work. The cutting temperature and surface roughness for different quantity of coolant are investigated by analysis of variance (ANOVA) - test and a multiple comparison method. ANOVA-test results signify that the average tool temperature and surface roughness depend on the amount of coolant. Based on Tukey's Honestly Significant Difference (HSD) method, one of the multiple comparison methods, the minimum level of coolant is 1.0 L/min with 2% mix ratio in the aspect of controlling tool temperature. F-test concludes that the amount of coolant used does not have any significant effect on specific cutting energy. Finally, Tukey method ascertains that 0.5 L/min with 6% mix ratio is the minimum level of coolant required in turning process without any serious degradation of the surface finish. Considering all aspects of cutting, the minimum coolant required is 1.0 L/min with 6% mix ratio. It is merely half the coolant currently used i.e. 2.0 L/min with 10% mix ratio. Minimal use of coolant not only economically desirable for reducing manufacturing cost but also it imparts fewer hazards to human health. Also, sparing use of coolant will eventually transform the turning process into a more environment-conscious manufacturing process.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.7
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• pp.58-65
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• 1999

Hard turning offers many possible benefits over grinding such as lower equipment costs, shorter setup time, reduced process steps and better surface integrity. Despite the amount of research in this area, there exists no data in the intermittent hard turning. The objective of this paper is to investigate the effect of CBN tool materials and machinability to an intermittent hard turning. To this end, different CBN materials were tested to evaluate the tool wear and surface roughness in an intermittent hard turning. It is found that low-CBN-content tool is better than high-CBN-content tool. Then, we discussed a cutting force, vibration, and CBN tool wear mechanism from the hard turning.