• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.38-43
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• 2003

The dimensions of die and workpiece are changed continuously during loading, unloading, and ejecting stage. Finally, to predict precisely the dimension of forged part and get the die dimension for the net-shape components, the analysis of die and workpiece should be evaluated from the loading to ejecting. Therefore, the experimental and FEM analysis are peformed to investigate the elastic characteristics at workpiece and die in the closed-die upsetting for ferrous material. FE techniques are proposed to consider the unloading and ejecting stages and estimate more precisely the dimension of forged part and die. The dimensional changes for the workpiece were evaluated quantatively during loading, unloading, and ejecting stages. The strains measured by the strain gages were compared with the estimated values by the FEM.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.62-67
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• 1998

An experimental study has been carried out to investigate casting process parameters which influence on the microstructures of cast preforms in casting/forging process of aluminum alloy. In the casting process, pouring temperature, pouring time, mold temperature, mold material, and, cooling method are selected as process parameters. With the cast preform, a forging test has been performed to compare mechanical properties of final products between casting/forging process and forging process. From the experimental results, low mold temperature and water cooling method are favorable for obtaining minute microstructures of cast preforms. Casting defects included in cast preforms. such as pores and shrinkage cavity, are eliminated by the forging process. And comparing cast/forged products with conventionally forged products, the former are almost as same as the latter in mechanical characteristics.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.03a
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• pp.149-158
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• 1994

Powder forged Connecting Rods have become attractive for use in automotive engines. The powder forging process offers beneficial material utilization as well as the minimization of finishing operations over that of conventionally forged rods. In the present work, the sintering behavior of Fe-2Cu-0.6C, optimum preform design and forgeability of various forging variables were investigated. Our data were generated using a newly proposed sub-scale con-rod developed specifically to simulate the powder forging process. We obtain optimum condition of sintering and powder forging process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.59-62
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• 2003

The precision cold forging of helical gear for steering pinion has been studied. Because of the large helix angle, there are many difficult problems to control the material flow and part dimension. The die shape was proposed to improve the flow of workpiece. In order to improve the dimensional accuracy of forged part, a FE analysis was performed. The proposed die shape drives to flow amicably workpiece. The applied load was reduced up to 10 percent, compared to the conventional-shaped-die. The elastic deformation of die has been investigated quantitatively by the 3-dimensional FE analysis. The die-land has been expanded up to $10{\mu}m$ on loading stage, based on the FEM results. Therefore, the elastic deformation amounts should be taken into consideration to improve the dimensional accuracy of forged helical gear.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.338-341
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• 2004

The dimension of forged part is different with the die dimension by the various effects, such as, elastic deformation and thermal effect. And, the difference amounts are not same according to the forging conditions, for example, forging mode, flow stress, etc. Therefore, the use of FEA is effective to predict and update the required die dimension. However, the variables for FE simulation are also as many as variables in the experiment. The variables give very much effect to the accuracy of FE results. At first, the material model is very deeply affected to the estimated dimension of forged part. And the considering of loading and ejecting stages is also important to increase the dimensional accuracy. The experiment and FEA are performed to investigate the dimensional changes and accuracy in cold forging. Two types of upsetting are used to survey the effects of forging mode and stages.

• Transactions of Materials Processing
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• v.12 no.7
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• pp.662-667
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• 2003

The dimensions of die and workpiece are changed continuously during loading, unloading, and ejecting stage. Finally, to predict precisely the dimension of forged part and get the die dimension for the net-shape components, the analysis of die and workpiece should be evaluated from the loading to ejecting. Therefore, the experimental and FEM analyses are performed to investigate the elastic characteristics at workpiece and die in the closed-die upsetting for ferrous material FE techniques are proposed to consider the unloading and ejecting stages and estimate more precisely the dimension of forged part and die. The dimensional changes fur the workpiece were evaluated quantatively during loading, unloading, and ejecting stages. The strains measured by the strain gages were compared with the estimated values by the FEM.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.370-373
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• 2008

Small size gas turbine disk requires good mechanical strength and creep properties at high temperature. In this study, Waspaloy was used as a superalloy to satisfy these specifications. The control of microstructure was needed to satisfy material properties at high temperature. In order to do this, we studied forging conditions and material analysis. Therefore die and preform design conducted so that hot forged gas turbine disk could have a good microstructure. The die and preform shapes are designed with consideration of the predefined hydraulic press capacity and the microstructure of forging product. Also we carried out the hot compression test for Waspaloy in various test conditions. From these results, we obtained the forging conditions as material temperature, die velocity etc. To verify these forging conditions, we conducted FE simulations by means of the DEFORM 2D-HT. In this study, the hot closed die and preform designs were completed to offer high temperature material properties of a small size gas turbine.

• Transactions of Materials Processing
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• v.18 no.6
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• pp.444-447
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• 2009

Piston crown to the hot forge a unified nature of the product has a shape with multi-level step forging process, so if you are not a mechanical professional, this process could lead to a significant loss to the material. Therefore, material technology in minor terms; continue to improve the collection rate that undamaged the product material. The piston crown and the manufacturing products such as marine diesel engines are being forged to reduce costs and to improve mechanical properties. Piston crown molding is a hot forging process that works in large volume forging products. Because of the size of the hard plastic material flow process for improving the design and actual field experience through advanced plastic technology, it is important to interpret the results. Also for many experimental plastic procedures, the accumulation of results is very important.

• The Journal of Advanced Prosthodontics
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• v.12 no.6
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• pp.369-375
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• 2020

PURPOSE. This study evaluated the availability of multi-directionally forged (MDF) titanium (Ti) as a component of removable partial dentures (RPDs). MDF-Ti remarkably improved the mechanical properties of RPDs due to its ultrafine-grained structure. MATERIALS AND METHODS. The wear resistance, plaque adhesion, and machinability of MDF-Ti were tested. As controls, commercially pure (CP) titanium was used for wear, plaque adhesion, and machinability tests. For wear resistance, the volume losses of the titanium teeth before and after wear tests were evaluated. Plaque adhesion was evaluated by the assay of Streptococcus mutans. In the machinability test, samples were cut and ground by a steel fissure bur and carborundum (SiC) point. An unpaired t-test was employed for the analysis of the significant differences between MDF-Ti and the control in the results for each test. RESULTS. Wear resistance and plaque adherence of MDF-Ti similar to those of CP-Ti (P>.05) were indicated. MDF-Ti exhibited significantly larger volume loss than CP-Ti in all conditions except 100/30,000 g/rpm in machinability tests (P<.05). CONCLUSION. Although the wear resistance and plaque adherence of MDF-Ti were comparable to those of controls, MDF-Ti showed better machinability than did CP-Ti. MDF-Ti could be used as a framework material for RPDs.

• Journal of Powder Materials
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• v.4 no.4
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• pp.258-267
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• 1997

The powder forging process is an attractive manufacturing route for bevel gears. It offers beneficial material utilization and the minimization of finishing operations over that of conventional hot forging. The paper describes the process conditions for the powder forging of bevel gear, for example, powder alloy design, preform design, deformation of sintered preform, forging processes. The characteristics of prototype gear are investigated with microstructure, the density distribution, surface roughness of tooth, bending strength test of tooth, etc. The results of the bending strength test may prove the mechanical properties of powder forged gear.