砂型透气性对产生铸件缺陷有很大的影响,在干型和湿型方面已有很多报导。负压造型的砂型在形成铸件缺陷方面,虽然考虑了真空泵的流量和砂型成型力等因素,但透气性也起着重要的作用。当砂型内压差小时,负压造型砂型的透气性与干型的基本透气性相同。而实 Sand permeability has a significant impact on casting defects, as has been reported for both dry and wet types. Negative pressure forming sand mold casting defects in the formation, although taking into account the vacuum pump flow and sand forming force and other factors, but permeability also plays an important role. When the pressure inside the sand is small, the air permeability of the negative pressure forming sand is the same as that of the dry type. And real