• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.31-40
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• 2003

In this paper, optimal cutting condition to minimize the form error in side wall machining with a flat end mill is studied. Cutting forces and tool deflection are calculated considering surface shape generated by the previous cutting such as roughing. Using the form error prediction method from tool deflection, optimal cutting condition considering form accuracy is investigated. Also, the effects of tool teeth number, tool geometry and cutting conditions on form error are analyzed. The characteristics and the difference of generated surface shape in up and down milling are discussed and over-cut free condition in up milling is presented. Form error reduction method through successive up and down milling is also suggested. The effectiveness and usefulness of the presented method are verified from a series of cutting experiments under various cutting conditions. It is confirmed that form error prediction from tool deflection in side wall machining can be used in optimal cutting condition selection and real time surface error simulation for CAD/CAM systems. This study also contributes to cutting process optimization for the improvement of form accuracy especially in precision die and mold manufacturing.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.43-51
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• 2004

A method for form error prediction in side wall machining with a flat end mill is suggested. Form error is predicted directly from the tool deflection without surface generation by cutting edge locus with time simulation. Developed model can predict the surface form error about three hundred times faster than the previous method. Cutting forces and tool deflection are calculated considering tool geometry, tool setting error and machine tool stiffness. The characteristics and the difference of generated surface shape in up milling and down milling are discussed. The usefulness of the presented method is verified from a set of experiments under various cutting conditions generally used in die and mold manufacturing. This study contributes to real time surface shape estimation and cutting process planning for the improvement of form accuracy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1784-1788
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• 2003

For the improvement of geometrical accuracy in end milling, cutting method and cutting condition selection are investigated in this paper. As machining processes are composed of several steps such as roughing, semi-finishing. and finishing, cutting forces and tool deflection are calculated considering surface shape generated by the previous cutting. The effects of tool teeth numbers, tool geometry, and cutting conditions on the form error are analyzed. Using the from error prediction method from tool deflection, cutting condition for geometrical accuracy improvement is discussed. The characteristics and the difference of generated surface shape in up and down milling are dealt with and over-cut free condition in up milling is presented. The form error reduction method by alternating up and down milling is also suggested. The effectiveness of the presented method is examined from a set of cutting tests under various cutting conditions. This research contributes to cutting process optimization for the geometrical accuracy improvement in die and mold manufacture.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.76-83
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• 2006

Machining accuracy is closely related with tool deflection induced by cutting forces. In this research, cutting forces and tool deflection in end milling are expressed as a closed form of tool rotational angle and cutting conditions. The discrete cutting fores caused by periodic tool entry and exit are represented as a continuous function using the Fourier series expansion. Tool deflection is predicted by direct integration of the distributed loads on cutting edges. Cutting conditions, tool geometry, run-outs and the stiffness of tool clamping part are considered together far cutting forces and tool deflection estimation. Compared with numerical methods, the presented method has advantages in prediction time reduction and the effects of feeding and run-outs on cutting forces and tool deflection can be analyzed quantitatively. This research can be effectively used in real time machining error estimation and cutting condition selection for error minimization since the form accuracy is easily predicted from tool deflection curve.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1811-1815
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• 2003

Investigated is the relationship between tool deflection and geometrical accuracy in side wall machining. Form error is predicted directly from the tool deflection without surface generation. Developed model can predict the surface form error about three hundred times faster than the previous method. Cutting forces and tool deflection are calculated considering tool geometry, tool setting error, and machine tool stiffness. The characteristics and the difference of generated surface shape in up milling and down milling are discussed. The usefulness of the presented method is verified from a set of experiments under various cutting conditions generally used in die and mold manufacture. This study contributes to real time surface shape estimation and cutting process planning for the improvement of geometrical accuracy.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.84-89
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• 2001

In recent years, there is increasing demand of esthetic design and complex function in aerospace, automobile and die/mold industry, which brings into limelight high-precision, high-efficient machining of sculptured surface. This paper deals with the establishment of the optimal tool path on free form surface in high speed ball end milling. Ball end milling is widely used for free form surface die and mold. In this machining, the cutting direction was changed with tool path. The cutting characteristics, such as cutting force and surface form are varied according to the variation of cutting directions. In this paper, the optimal tool path with down cutting in free form surface cutting is suggested.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.383-384
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• 2009

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.4
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• pp.50-55
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• 2004

Because of the development in mold industries, the geometrical form accuracy of the milled surface is getting more and more important. It has been known that the geometrical form accuracy is affected by machine conditions, cutting conditions, tool conditions and tool path and so on. Among them, the tool approaching path causes the change in material removal per tooth at the end of each machining cycle. And, this change generates the geometrical form error around the region where the tool engages the workpiece initially. So, it is impossible to eliminate the geometrical error caused by the tool approaching path. Thus, characteristics of this geometrical error are studied analytically and experimentally to minimize this region.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.35-44
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• 1999

The performance of interrupted cutting operations like milling is consideraly affected by cuter runout. In this study, cutter runout is selected as an important machining parameter for evaluation of machinability in ball-end milling and caused from misalignments of tool and holder, unbalanced mass of parts and tool deflection under machining. To evaluate the machinability due to cutter runout, the rotating accuracy of spindle, cutting force and surface roughness are measured. The rotating characteristics of spindle in each revolution speed were investigated by cutter runout in freeload. The predicted surface form of workpiece by measuring cutter runout data was compared with real surfaces. The results show that measuring runout with high response gap sensor is useful for studying the phenomenon of high-speed machining and the monitor surface form using in-process runout measurements in ball-end milling is possible.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.9-23
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• 1993

Free-form surface machining is usually performed with an NC milling machine and a ball end milling cutter. Since this conventional method is basically sculpting on a plane, it is not suitable for three dimensional body machining. This article will introduce a new machining method for three dimensional body with free-form surface and newly developed machine tool suitable for such machining.