| Summary: | 碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 106 === Insulator has been widely used in our livelihood, industrial, medical and military fields, especially in the working environment of the high-voltage. In general, the high voltage insulator is playing an integral role. The high voltage insulator is often made by the ceramic material. The ceramic insulators generally are manufactured by utilizing ceramic powder injection molding technology, which satisfies a large number of requirements for the consumer. However, during injection molding, some cracks on the surface of the product are common defects in appearance, and those problems are often observed in products after debinding and sintering. However, some recent literatures have proposed that the crack problem might be caused by uneven shrinkage of green parts during injection molding. But the specific correlation between cracks on these surfaces and injection molding of green parts has not been fully understood yet.
This study applied both of numerical simulation and experimental studies to explore the specific correlation between cracks on the surface of high-voltage insulators and shrinkage variation after the green parts were injected. Firstly, we have tried to find out the major factors to cause high volume shrinkage region. Then we have proved that the cracks happened regions are matched with that of higher volume shrinkage areas of the green parts numerically. On the other hand, we also performed experimental tests to verify the numerical simulation. Results showed that the real cracks happened regions are matched with that of numerical simulation predicted. Moreover, to overcome the crack problem, the operation conditions have been optimized using CAE (Moldex3D) software. In our real setting, melt temperature is reduced from 160 ℃ to 150 ℃, and packing pressure is increased from 31 MPa to 62 MPa, the crack problem can be totally removed. The correlation between crack problem and the volume shrinkage of the green part is validated.
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