Discussion on "proportional solidification technology" for nodular iron casting method

H ow should the graphitization expansion be reasonably utilized to feed nodular iron castings? H ow should the consideration be given to both feeding from feeders and self-feeding by expansion? These two problem s are the hot spotsofdiscussion on feeding m ethod ofnodulariron castings at present. In this regard, reference [1] published som e viewpointswhich cause differentcom m ents.W ith the wish to prom ote the discussion on shrinkage problem sofnodulariron castings and based on his investig…

Discussion on "proportional solidification technology" for nodular iron casting method

The Proportional Solidification Technology believes that advancing the expansion of graphite precipitation is favorable for fully utilizing the expansion to offset the contraction and minimizing feeder size. But this author has proved that advancing the expansion is unfavorable for both feeding from the feeder and the self-feeding by expansion. On contrary, advancing the contraction is favorable for both kinds of feeding and favorable for avoiding shrinkage. The feeding efficiency of feeders cannot be increased by advancing the expansion of the casting, but can only be increased by accelerating cooling and contraction of the casting, and (or) by delaying the freezing of the feeders. In order to fully utilize the expansion to offset the contraction, it is a must to ensure that all inlets and outlets of a casting being poured are blocked rapidly at the moment when pouring is finished. It is pointed out that blocking at the earlier frozen feeder neck is unfavorable for both feeding from the feeder and the self-feeding by expansion; whereas blocking at earlier frozen ingates is favorable for both kinds of feeding.