• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.4
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• pp.157-166
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• 2022

In the case of a die-casting process, defects that are difficult to confirm by visual inspection, such as shrinkage bubbles, may occur due to an error in maintaining a vacuum state. Since these casting defects are discovered during post-processing operations such as heat treatment or finishing work, they cannot be taken in advance at the casting time, which can cause a large number of defects. In this study, we propose an approach that can predict the occurrence of casting defects by defect type using machine learning technology based on casting parameter data collected from equipment in the die casting process in real time. Die-casting parameter data can basically be collected through the casting equipment controller. In order to perform classification analysis for predicting defects by defect type, labeling of casting parameters must be performed. In this study, first, the defective data set is separated by performing the primary clustering based on the total defect rate obtained during the post-processing. Second, the secondary cluster analysis is performed using the defect rate by type for the separated defect data set, and the labeling task is performed by defect type using the cluster analysis result. Finally, a classification learning model is created by collecting the entire labeled data set, and a real-time monitoring system for defect prediction using LabView and Python was implemented. When a defect is predicted, notification is performed so that the operator can cope with it, such as displaying on the monitoring screen and alarm notification.

• Design & Manufacturing
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• v.9 no.1
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• pp.31-35
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• 2015

Recently, life expectancy increased in the development of medicine, the need for health has increased. Market for medical equipment is growing rapidly to an increase in the interest in health and aging worldwide. It is a device intended for ultra sensitive cleavage process of bone during joint replacement surgery on a technical advanced surgery, finishing, and hole. Domestic demand of the hand piece is a necessary condition on an ongoing basis. However, hand piece was made on the basis of the experience of many years in the country Japan, Germany, and the United States has spread to more than 90% domestic market. Feel the need for the development of the hand piece in the country, many companies are trying to in-house production hand piece. In an attempt to solve the problems with the hand piece of the present, in this paper, it was supposed to be a study of rechargeable hand piece to replace the existing pneumatic.

• Design & Manufacturing
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• v.6 no.2
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• pp.24-30
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• 2012

In this study, the hot forging technology for precision forming of spline teeth of the inner race in the auto-transmission was developed in order to minimize its finishing allowance. Several blocker and finisher shapes for the precision hot forging process of the inner race were proposed and the forging processes were analyzed using the three-dimensional finite element method. The optimum hot forging process was obtained considering some parameters such as metal flow patterns, forging defects and forming load. Blocker and finisher dies for the hot forging process were designed by selecting the most suitable shapes obtained from the finite element analysis. Experimental works were also performed in order to verify the optimum design of hot forging process.

• Design & Manufacturing
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• v.2 no.6
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• pp.11-16
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• 2008

In order to satisfy the customer's variant needs for a product quality in recent years, a demand for developing higher precision machining technologies in a lot of application areas such as automobile, cellular phone and semiconductor has been increased more and more. Micro-magnetic induced polishing(${\mu}-MIP$) process is one of these precision technologies. In this study, to verify the parameters' effect of the ${\mu}-MIP$ process on the surface roughness improvement of the inclined workpiece, well planned experiment which was called the design of experiments was carried out. Considered parameters were spindle speed, inductor current, abrasive configuration and working gap between the workpiece and the solid tool. As a result, it was seen that the inductor current and the working gap greatly affected the surface roughness improvement. And to predict the surface roughness of the inclined workpiece, S/N ratio and first-order response surface model was developed.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.147-154
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• 2003

An effective die-polishing robot system is developed. ATC (Automatic Tool Change), tool posture angle control, and robot program for polishing application are developed and integrated into a robotic system that consists of a robot, pneumatic grinding tool, and grinding abrasives (papers and special films). ATC is specifically designed to exchange whole grinding tool set for complete unmanned operation. A tool posture angle control system is developed for the tools to maintain a specified skew angle rather than right angle on the surface for best finishing results. A PC and the robot controller control ATC and tool posture angle. Also, there have been more considerations on enhancing the performance of the system. Elastic material is inserted between the grinding pad and the holder for better grinding contact. Robot path data are generated automatically from the NC data of previous machining process.

• Design & Manufacturing
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• v.14 no.1
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• pp.56-62
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• 2020

An electron beam was used to mainly utilize for polishing, finishing, welding, a lithography process, etc. Due to the high technical level of difficulty of high-power density electron beam, it is difficult to secure related technologies. In this study, research was carried out to improve the machinability by developing the vaporized amplification sheets to realize the electron beam drilling technology. Their vaporized amplification sheets were analyzed by using the measurement of chemical and composition, which is such as TGA, SEM. We analyzed micro-hole processing using a microscope. Also, the thermal characteristics of vaporized amplification sheets are highly significant for applying to high-power density electron beam technique. So, we finished the vaporized amplification sheets according to the process conditions and analyzed it according to the machining conditions of the electron beam. It was confirmed that the effect on the experimental results differs depending on the influence of the metal powder contained in the developed material.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.59-65
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• 1996

There are many difficulties in automatic polishing for die & mold surfaces. Even though the process has been studied in the past 15 years, it has not been achieved yet, but by the process of actual hand work of well-skilled workers. A new magentic assisted polishing process, which is one of the potential methods for automation of surface finishing has been studied in the past 10 years by colleagues. The process has many merits, but on the other hand also has demerits, one being low efficiency of grindability by comparision with wheel polish. Therefore, some attempts were tried to improve the grindability by adopting electropolishing, ultra-high speed milling, 5-axis controlled machine etc... most recently by colleagues. This paper also aims to improve the efficiency of polishing by introducing the easily-polished shape surface cutting method equalizing the tool feed per revolution to the pick feed. This cutting method was experimentally confirmed to have sufficient grindability to polish milled surface (with $10{{\mu}m}$Rmax surface roughness) into mirror surface (with $0.4{{\mu}m}$Rmax surface roughness).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.354-357
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• 2005

When Ti-6Al-4V is used in long steam turbine blades, the main issues are how to improve the fatigue strength as a problem of internal quality and how to forge the thinnest possible blades as problem of dimensional precision. To assure an excellent fatigue strength, it is important to make the two phase fine and equiaxial structure by providing enough plastic deformation in the two phase$(\alpha\;phase/\beta\;phase)$ temperature region. Accordingly, it needs to predict that forging temperature, preform design and forging velocity in forging process. To achieve this end, the two steps forging process was suggested to forge the thin and twisted blades with a precision hammer considering die forces and metal flow. Two steps forging process consists of the flattening forging process and finishing forging process. Process in forging of a 1016mm long steam turbine blade is designed by the finite element method. This study attempts to derive systematic design procedures for process design in the forging. Forging parameters was analyzed in two-dimensional plane-strain simulation and two steps forging process carried out in three-dimensional simulation. Consequently, optimal forging process parameters of long steam turbine blades in Ti-6Al-4V with a high dimensional precision are selected in the hammer die forging.

• Design & Manufacturing
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• v.11 no.2
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• pp.20-24
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• 2017

Recent industrial developments are constantly advancing, and rapid technological development is demanding high technology level in related fields. The need for polishing is increasing even more to improve quality. In order to improve the surface quality, the final finishing process or polishing process is a very important part. Research on super precise polishing method using MR fluid is actively being carried out in domestic and foreign countries. Fine magnetic abrasive grains are aligned in the direction of a magnetic force line formed by a magnetic field and serve as a brush to polish a metal surface. This method has the advantage that the shape of the tool is not fixed and is not affected by the shape of the workpiece or the machining area. We will design the electromagnets for the MR polish polishing system and apply the magnetic field analysis using the magnetic field analysis program (ANSYS). The data obtained through this process suggests an efficient method to increase the magnetic flux density important for polishing. We will investigate the influence of the Al6061-T6 specimen on the surface of the MR polishing machine based on the optimized design.

• Textile Coloration and Finishing
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• v.31 no.3
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• pp.177-186
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• 2019

In this study, we investigated for synthetic hydrotalcite in chloroprene rubber foam. Experiments were carried out to find the optimum content ratio by controlling the contents of MgO and Hydrotalcite. Swelling test in toluene immersion was made to measure the crosslinking density of CR foams, and the cure properties were investigated with flat die rheometer and Mooney viscosity. The difference of hardness, tensile strength and elongation at break were observed after immersing in 7% NaCl or 21% NaCl solutions for a day and four days. In addition, the volume change and water content remaining in CR foam were measured after immersing NaCl solution. As content of MgO increased, the value of the cure torque tended to increase, but it was almost constant above 2phr of MgO. However, the Mooney viscosity decreased with increasing MgO content. The crosslinking density, determined by the swelling ratio, showed that the CR compound without MgO showed a higher degree of swelling. When the content of hydrotalcite/MgO was 3:2, it was the lowest volume change of CR form. Also, As the content of hydrotalcite decreased, the difference of mechanical properties before and after immersion NaCl solution increased.