• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.8-15
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• 2004

A significant error in the end milling processes is generated due to using slender tools of which the strengths are not sufficient. In order to obtain the desired machining accuracy, therefore, it is general that at first the rough cut is implemented, then the finish cut is followed. The rough cut eliminates large volume and the finish cut does the remained part. This remaining portion after the rough cut is called as the finish allowance. Larger finish allowances make it hard to get precise dimensions at a following finish cut. Smaller finish allowances are helpful for good dimension, but it sometimes is responsible for inferior surface qualities and over cuts. This study suggests a guidance for the optimum finish allowance for machining accuracy improvement, in which the rough cuts are regulated to remain the desired margins without any over cuts. Some experiments were carried out with various cutting conditions including the change of tool strengths and depth of cuts, and also extended to up millings as well as down millings.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1681-1688
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• 2000

A dynamic model for the prediction of surface topography in high speed end milling process is developed. In this model the effect of tool runout, tool deflection and spindle vibration were taken in to account. An equivalent diameter of end mill is obtained by finite element method and tool deflection experiment. A modal parameter of machine tool is extracted by using frequency response function. The tool deflection, spindle vibration chip thickness and cutting force were calculated in dynamic cutting condition. The tooth pass is calculated at the current angular position for each point of contact between the tool and the workpiece. The new dynamic model for surface predition are compared with several investigated model. It is shown that new dynamic model is more effective to predict surface topography than other suggested models. In high speed end milling, the tool vibration has more effect on surface topography than the tool deflection.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.12
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• pp.143-152
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• 1997

The deflection of an end mill is very important in machining process and cutting simulation because it affects directly workpiece accuracy, cutting force, and chattering. In this study, the deflection of the end mill was studied both experimentally and by using finite element analysis. And the moment of inertia of cross sections of the helical end mill is calculated for the determination of the relation between geometry of radial cross section and rigidity of the tools. Using the Bernoulli-Euler beam theory and the concept of equivalent diameter, a deflection model is established, which includes most influences from tool geomety parameters. It was found that helix angle attenuates the rigidity of the end mill by the finite element analysis. As a result, the equivalent diameter is determined by tooth number, inscribed diameter ratio, cross sectional geometry and helix angle. Because the relation betweem equivalent diameter and each factor is nonlinear, neural network is used to decide the equivalent diameter. Input patterns and desired outputs for the neural network are obtained by FEM analysis in several case of end milling operations.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.2
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• pp.50-64
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• 1994

Cutter deflections in the ball-end milling process is one of the main causes of the machining errors on a free-form surface. In order to avoid machining errors in this process, a methodology avoiding these machining errors on the free-form surfaces has been developed. In this method, feedrates in the finish cuts are adjusted for the prevention of machining errors. A model for the prediction of machining errors on the free-form surface is analytically derived as a function of feed and normal vector at the surface of contact point by the cutter. This model is applied to the dertermination of the adjusted feedrates which satisfy the machining tolerance of the surface. In the finish cuts of a simple curved surface, the suggested model is examined by the measurements of the generated machining error on this surface. And also, this surface is machined with the adjusted feedrates for the given machining tolerance. The measured machining errors on this surface are compared with the given tolerance. In this comparisons, it is shown that the predicted errors are fairly good agreement with the test results.