• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.4
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• pp.87-93
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• 2021

The mold industry is competitive, and mold should be processed under optimal conditions for efficient processing. However, the cutting conditions of the ball-end mill, which are a major factor in mold processing, are mostly set empirically, and considerable research is required for increasing the tool life and processing accuracy. In this study, a tool dynamometer and an eddy current sensor were used along with NI-DAQ, a data acquisition device, to obtain characteristic values of the cutting force and tool deformation during the ball end-mill machining of inclined surfaces at a machining center. The cutting force and tool deformation were measured in an experiment. It was found that the tool received the greatest cutting force at the end of the machining process, and the deformation of the tool increased rapidly. Furthermore, the cutting force tended to increase with the angle and number of rotations. The deformation increased rapidly during the machining of a 45° inclined surface.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.139-144
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• 1991

Chip flow angle is one of the important factors to be determined for the scheme of Chip Control. Up to now, however, a dependable way to predict the chip flow angle in practical cutting has not been established satisfactorily. In this paper a rather simple theoretical prediction of chip flow angle is tried based on some already widely confirmed hypotheses. The developed equation of chip flow angle contains the parameters of depth of cut d, feed rate f, nose radius $r_{n}$ side cutting edge angle $C_{s}$, side rake angle .alpha.$_{s}$ and back rake angle .alpha.$_{b}$. Theoretical results of chip flow angle given by this study bas been shown in a good agreement with experimental ones.s.s.s.s.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.5
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• pp.73-80
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• 2002

In this study, work materials of the ree form surface shape was machined by ball end mill cutter according to the change of cutting location and depth, and the acquired data of cutting force, tool deflection and shape accuracy were analyzed. Cutting force results were obtained with tool dynamometer and tool deflection values were measured by a couple of eddy-current sensors. Shape accuracy was obtained by roundness tester and surface profile measuring machine. As inclination angle was decreased, cutting force was increased. Cutting force showed large value at $105^{\circ}$ and $150^{\circ}$. Tool deflection was less at down milling than at up milling, decreased at 45$^{\circ}$ and 120$^{\circ}$, and shown large tool deflection at $150^{\circ}$. Roughness values were found to be bad in the inside of surface shape tool deflection. Surface accuracy was obtained better precision in down milling than in up milling.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.3
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• pp.57-65
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• 1997

In this study, a cutting force in the Ball-end milling process is calculated using Z-map. Z-map can describe any type of cutting area resulting from the previous cutting geometry and cutting condition. Cutting edge of a ball-end mill is divided into infinitesimal cutting edge elements and the position of the ele- ment is projected to the cutter plane normal to the Z axis. Also the cutting area in the cutter plane is obtained by using the Z-map. Comparing this projected position with cutting area, it can be determined whether it engages in the cutting. The cutting force can be calculated by numerical integration of cutting force acting on the engaged cutting edge elements. A series of experiments such as contouring and upward/downward ramp cutting was performed to verify the calculated cutting force.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.74-79
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• 1996

The wear of partially coated pinion cutters under several cutting conditions was studied. In the realm of this experiment, chipping was a dominant tool wear mechanism and flank wear was much larger than crater wear. Under the condition of relatively low rotary feed and low radial feed rate, the wear due to chipping was concentrated at the nose part of pinion cutter. Increasing of rotary feed and radial feed rate alleviated the concentration of chipping at nose and prolonged tool life.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.7
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• pp.112-119
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• 2001

In modern manufacturing, many products that have geometrically complicated features, including three-dimensional sculptured surfaces, are being designed and produced to meet various sophisticated functional specifications. The cutting force is required not only for the design of machine and cutting tools, but also for the determination of the cutting conditions for the various machining operations. The ball-end mill is deflected by the cutting force and, the tool deflection is one of the main reasons of the machining errors on a free-form surface. Hence, The cutting force generated in the ball-end milling is the most important property of the machining. The purpose of this study is to find the characteristics of the cutting force in inclined plane and the resultant machining errors in the ball-end milling process. Although the depth of cut is constant in the inclined plane, the cutting force area varies due to the hemisphere of the ball-end mill.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.892-897
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• 2000

In this study, tap wear was analyzed not only to predict the tap life time but also to propose an improved tap design. Because rake angle and thread relief of tap are the significant factors in geometry of tap, these two factors were picked as the experiment variables. The experiment was conducted with six types of tap which have 6$^{\circ}$ , 8$^{\circ}$ and 12$^{\circ}$ of rake angles with 0,08mm and 0.14 mm of thread relief. From the measured cutting force, it could be known that cutting torque was low at the large the rake thread relief and tool life was long as rake angle became large. Eventually, tool life is longest when rake angle is 12$^{\circ}$ and the with 0.08mm thread relief. Aand the width of crater wear and that of flank wear were measured when a tapping torque was 20 [$kg_f$-mm] . Most of the measured values were above the width of tool wear[$V_B$=O.O3m], which means that tool life is over.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.6
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• pp.1121-1140
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• 1992

In metal cutting the shape of generated chip varies according to cutting conditions, characteristics of workpiece and geometry of cutting tool. The best surface roughness of machined workpiece is obtained when generating flow type contrinuous chip. If the generated chip is not broken, that is not only tangled workpiece and cutting tool, but also may give damage on the machined surface of workpiece or danger for a operator. The flow type continuous chip may bring the low productivity in high speed any heavy cutting, automatic machining process and non-human factory. There are two type of chip break process ; controlling cutting condition and using chip breaker. In present study we carried out the experiment on new type chip breaker compared with conventional type and proved the efficiency of a new type and showed the chip break condition to be applied in actual metal cutting. In the experiment SM 20 C as a workpiece material and WC as a tool material were used and cutting speed of 30-150m/min, feed of 0.071-0.210mm/rev and depth of cut of 1mm were applied as cutting condition. The results of the experiment are as follows : (1) The mechanism of chip curl can be explained more clearly by plastic flow of workpiece material and moment of shearing force. (2) The most effective radius of curled chip and flat distance from cutting edge is 2.0-2.5mm and 1.5mm in both types. (3) The effective inclination angle of chip break surface and side cutting edge angle are 30.deg.- 45.deg. and 20.deg. in conventional type, while the radius of arc surface, lower arc angle A, upper arc angle B and side cutting edge angle are 3mm, 20.deg.- 45.deg., 0.deg.- 45.deg. and 10.deg.- 20.deg. in new type. (4) The probability to be obtained 100% chip breaking ratio is much higher in new type than in conventional type.