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金属注射成形注射料在模腔中的流动是粉末与粘结剂的混合流动,其粘性行为与仅含粘结剂的单相流动有所不同。为研究注射料在微模腔中注射成形的粘性行为和微注射工艺的尺度适应性,在RH2000毛细管粘度仪依次安装直径0.3～2.0mm的7个毛细管,分别在160～220℃间的4个温度下对平均粒度为16μm的316L不锈钢注射料进行一系列粘度测试;测试显示注射料在同样的注射温度和切应变率下,应用不同管径的毛细管测试所得粘度存在差异的现象;解释壁面边界滑移速度是导致测试粘度差异的原因,分析影响粘度测试结果的因素;基于一系列的粘度测试结果,标定出壁面边界滑移速度的大小;提出注射料最小临界尺度的概念和标定方法,为微细金属注射成形工艺的尺度适应性研究提供有益的参考。
The flow of metal injection molded injection material in the mold cavity is a mixed flow of powder and binder with a viscous behavior that is different from the single phase flow with binder alone. In order to study the viscous behavior of injection molding material in the micro-cavity and the micro-injection process adaptability, seven capillary tubes with a diameter of 0.3-2.0mm were installed in RH2000 capillary viscometer, and four capillary tubes A series of viscosity tests were performed on 316L stainless steel shot with an average particle size of 16μm at different temperatures. The results showed that there was a difference in the viscosities of the injected shots with different tube diameters at the same injection temperature and shear rate. Slippage velocity is the reason that leads to the difference of test viscosity and the factors that affect the viscosity test result are analyzed. Based on a series of viscosity test results, the slippage velocity of wall boundary is calibrated. The concept and calibration method of minimum critical dimension of injection material is proposed Micro-metal injection molding process scale adaptability study provides a useful reference.