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Vermicular graphite cast iron as a new type of cast iron materials , engine accessories ideal material , but the production process is difficult , long-standing production quality has been unstable once since I plant severe rejection rate , up to when the rejection rate as high as 31.47% , which Utah gas shrinkage defects are the most serious. Technology research theme to 6M/6L vermicular graphite iron cylinder cover gas shrinkage defects , in the gas shrinkage causes the in-depth analysis on the basis of the proposed process measures to overcome the compacted graphite iron cylinder head gas shrinkage , so that the gas shrinkage Defects highest scrap rate of 31.47% down to 0.69% . The root causes of gas shrinkage is the result of the role of \. Conversely , if the solidification early formation of shrinkage, \The poor quality of the production of hot metal , the charge is not pure , unstable chemical composition , the creep rate instability , improper gating system and exhaust system design , casting Heavy and local overheating of the hot spot are factors that cause gas shrinkage . Optimal design by taking the gating system optimization design , the exhaust system , strengthen the purification treatment to improve the quality of molten iron , and strictly control the creep rate , speed up the cooling rate of the hot section parts and process measures , achieved significant results 6M/6L vermicular graphite cast iron cylinder head basic eliminate gas shrinkage defects .
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