Study On The Blow Hole Defect Cause Of Formation And Countermeasures In Miniature Ultrathin Zinc Alloy Die Castings

The pore is an ordinary defect in miniature Zinc alloy die castings. The mainreasons for the pore defects are the raw material of zinc alloy (especially secondhandmaterials), the design of die casting mold (especially the ingate and flow gate) and thedie-casting technique (especially the parameter of mold temperature). It is significantthat employing the method of combining computer numerical simulation technique withexperiments to research the pore defects, and this method also plays an important rolefor the optimization of the die-casting process and the improvement of the quality of diecastings.This study focused on the refinement of NH4Cl to varying Zinc alloys so as tocompare the differences before and after refinement. It showed that, with suitablerefinement, we could obtain the microstructure with less or no inclusions, therebydecreasing the amount of porosity.The results indicated that, for the ultrathin miniature die castings, it was moreadvantageous to prevent the emergence of pore defects if the ingate section was ellipseinstead of ladder type. For the die-casting process of ultrathin miniature HDMI shell, wesuccessfully predicted the positions of pore defects using CAE numerical simulationsoftware. Combing the numerical simulation with DOE experiment method, the correctdesign parameters for the ingate of gating system has been found, and the experientialformula of thick-wall Zinc alloy die castings has been revised. Meanwhile, theinspection standards for the interior and exterior qualities of ultrathin miniature diecastings has also been established. Furthermore, the standards can be applied inpractical production.The experimental systems for measuring die-casting temperature ofminiature, ultrathin, hollow and abnormal Zinc alloy die castings has beendesigned and built. The temperatures of production surface were obtained usingthe software of CAE and IMC FAMOS. Through the investigation of interiorand exterior qualities of production under best temperature field, the resultsindicated that the distribution of mold temperature is an essential factor for thequalities when processing the ultrathin miniature hollow and abnormal Zincalloy die castings.