Analysis and Measures for Gas Hole and Shrinkage Defects in Large QT400-15 Tray Castings
This article introduces the structure and technical requirements of ductile iron castings for pallets,elaborates on the original production process and the location as well as characteristics of porosity and shrinkage in castings.An analysis was conducted on the causes of porosity and shrinkage defects in the tray,and it was found that excessive moisture in the mold led to the appearance of invasive porosity defects,while improper use of cold iron resulted in shrinkage defects at the hot spot.By adopting measures such as baking sand cores and molds to reduce moisture content,improving sand mold permeability and increasing air output,optimizing the placement and shape of cold iron to eliminate hot spots,increasing riser size to enhance liquid shrinkage,and increasing the carbon content of molten iron to enhance self feeding ability,the porosity and shrinkage defects of ductile iron pallets have been eliminated.No porosity or shrinkage defects were found in the same type of tray castings produced in the verification test.
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