• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.773-774
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• 2011

• Elastomers and Composites
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• v.42 no.2
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• pp.86-92
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• 2007

A few of polytetrafluoroethylene(PTFE) membranes and PTFE fine powders were analyzed to chooce an optimum resin. The bi-axial stretching process was developed to set up the foundation of the preparation process and control the pore size and porosity of PTFE membrane. The pretreatment of PTFE fine powder used in the preparation process for PTFE was needed. The mixing of additives, the ripening of mixture, paste extrusion process of ripening powder, calendering process and the bi-axial process were conducted for controlling pore size, porosity and thckness of membrane. The aftertreatment which strengthened the mechanical properties was necessary. The control of pore size and porosity of the membrane were determined. The ratio of PTFE fine powder and additives at the paste extrusion process, the ripening time, the ripening temperature and the parameters of temperature and pressure at the paste extrusion process were optimized.

• Transactions of Materials Processing
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• v.10 no.1
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• pp.59-66
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• 2001

Recently, the technology of incremental forming for sheet metal components has drawn attention for small-batch productions. In the present investigation, a forming tool containing a freely-rotating ball was developed and applied to forming of various shapes with full annealed Al 1050 sheet. Deformation characteristics occurring during forming with this tool was examined through FEM analysis and grid measurement. It was found that deformation modes developed along a straight path and around a corner are close to those of plane-strain and equi-biaxial stretching, respectively, and that cracks occur mostly at corners for the same depth of tool. FEM analysis was successfully applied to this special type of forming process and provided comparable results to the measurements from experiment.