Papers by Author: S.L. Ko

Abstract: The sharp burrs produced by plastic deformation during machining of the precision components deteriorates the precision and performance of a machine. Thus, effective removal of the burrs may improve productivity and performance of the machinery. This study was conducted based on the experiment to remove fine burrs produced during machining process using the magnetic abrasive finishing method. The magnetic abrasive finishing using the abrasive feature of an abrasive and the magnetic nature of iron is an abrasive method to brush the burrs with iron powder that has a cohesive power due to the line of induction. The purpose of this study is to remove the burrs at intersecting holes which are difficult to access with tools, using the magnetic abrasive finishing method. Special tool is designed for deburring micro burr at intersecting holes. To find the proper deburring condition, gap distance, rotational speed of inductor, components of powder and effect of coolant are analyzed.

Abstract: The paper proposes a model of burr formation in feed direction during turning operation. Two cases have been considered in the model: continuous and discontinuous burr development. A computer program, made on the base of the model, allows simulation of burr development, and predicting burr form and dimensions. Experimental verification of the program showed that the model is suitable for the simulation of burr development in both continuous and discontinuous cases of burr formation. The experiment also proved that burr thickness can be predicted with considerable accuracy and that burr height can be determined with a maximum error of about 30%.

Abstract: Several types of inductors with permanent magnets for deburring using the MAF process were investigated in this paper. The magnetic intensity of each system was measured at working gap to determine the proper system. Using the inductor with a permanent magnet, which was designed and manufactured as a result of the investigation, the heterogeneity of the finishing process and the variations in the location of the magnet poles and the amount of the powder were analyzed during the deburring process. The characteristic curve was calculated from the experimental data and used to compare the performance of each inductor. Under similar conditions, the permanent magnet inductor showed superior performance compared to the electromagnetic inductor in the deburring process.

Abstract: In this paper, the new technique involving comparison and optimization of conditions for Magnetic Abrasive Finishing (MAF) is suggested, taking into account the basic laws stated for process MAF. The formulas for the calculation of the criteria for optimization are created when the process MAF is used for polishing, removal of burrs, and other purposes. The application of the technique is shown in an experiment on the optimization conditions for the removal of burrs after drilling using the MAF method. The technique can be used after standards for this process are developed.

Abstract: This paper analyzes the effectiveness of using Magnetic Abrasive Finishing (MAF) to remove burrs on drilled holes located on planes. Basic elements of the equipment in this method are a magnetic inductor; powder with magnetic and abrasive properties, which serves as the cutting tool; and the face electromagnetic inductor and the vibrating table, which were developed for deburring and finishing on flat surfaces. The performance of magnetic abrasive powders produced by industry is also evaluated. A new technique was developed to compare the performance of the magnetic abrasive powders and to find the powder that is appropriate for finishing and deburring drilled holes placed on a plane steel surface.

Abstract: Micro burrs formed in micro parts are not subject to be removed by the conventional deburring method for marco parts. Magnetic abrasive deburring method which was proved to be effective for small burrs are applied for deburring the micro burr in electric gun parts used in TV monitor. A specific magnetic inductor is designed and manufactured for this part. To improve the deburring performance, vibration table is used for increasing the relative velocity. To evaluate the deburring capability and surface finishing, edge shape, surface roughness and composition of surface material are measured precisely. It is verified the chemical composition of surface is not affected by the powder composition when the proper powder are used with coolant.

Abstract: The paper represents an experimental study of the burr formation mechanism in feed direction. The influence of tool angles and workpiece angles, as well as and other cutting conditions on burr dimensions is considered. The work contains experimental graphs of burr cross-sections obtained using a laser measurement system at various stages of burr formation. The analysis of the experimental work shows that, depending on the cutting conditions, a few mechanisms of burr formation can be distinguished. The study could be useful in the search for optimal tool geometry for burr minimization and for the modeling of a burr formation mechanism.