(1) the inoculant addition of nodular cast iron is generally more than that of gray cast iron.
(2) if the hot metal after inoculation treatment is poured in for a long time, due to the decrease of inoculation amount, the addition amount should be increased.
(3) chilling is easy to occur in thin-walled castings, so the amount of inoculant should be increased accordingly.
(4) when there is more slag in hot metal, the inoculant will be wrapped as soon as it comes into contact, so it is difficult to melt, so the amount of inoculant will increase accordingly.

(5) Excessive addition of inoculant will lead to excessive slag, lower temperature of molten iron and shrinkage cavity produced by eutectic group. If the inoculant block is too large, it will not be able to inoculate the molten iron evenly, and the unmelted inoculant will be poured into the cavity; If the block is too small, it is easy to oxidize and cause slag, and it is also easy to develop gestation recession.