陶瓷粉末微射出成型之實驗探討
Date Issued
2004
Date
2004
Author(s)
林柏峮
DOI
zh-TW
Abstract
Recently the micro-injection molding has drawn the attention of many researches; but not too much on the micro powder injection molding. This research is devoted to investigating the powder injection molding of micro parts. Al2O3 powders with the average diameter of 400nm compounded with polymer binders can be injection molded to fabricate micro thin tensile test plates. A lab-made impact type micro-injection molding machine was used in this study. There are two aspects in this study: The first one is to study the moldability of the thin parts and to study the effects of processing conditions on molding of micro parts. The second one is to observe the mold filling process in a mold implemented with transparent tempered glass window with aid of high speed video camera.
The results of the first study reveal the impact air pressure has to be high enough to prevent short shots. Increasing the mold and melt temperature can enhance the filling capacity. The thin tensile test plates with the thickness of 150μm can be molded using the impact type micro-injection molding machine. If the green parts are molded with too low air impact pressure, the residual stress of final parts will be high and cause warpage. Consistent shrinkage can be obtained if the green parts are molded with high mold and melt temperatures. The shrinkage along the flow direction is higher than that in across the flow direction.
The observation of the micro powder injection molding during filling process shows that the low impact air pressure causes flow mark and shrinkage holes at the edge far from the gate. On the contrary, too high on impact air pressure can cause the jetting phenomenon. The melt-front during filling the cavity of thin tensile test plates with thickness of 150μm is smoother than those observed in cavity of 200μm thick. When the melt temperature reaches beyond 170℃, the influence of mold temperature upon the filling of 150μm cavity becomes insignificant. The cavity can be filled in less than 0.002 second.
Subjects
流動觀察
拉伸試片
氧化鋁
粉末微射出成型
Micro-PIM
Visualization
Tensile Test Plate
Alumina
Type
thesis
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