How long do you leave your cast iron in the sand after you pour .......and if pulled when still warm ....or wait tell it's cold does it effect surface . Finish Thanks just curious Todd
Small castings 15-20 minutes, large chunky castings 60-90 minutes. I make sure that the casting is not red hot and if it is I cover it with sand again until it has stopped glowing. Surface finish is very good when the casting is not red hot.
Does not matter. Once the liquid metal has solidified there is nothing else that will affect the surface. May make them easier to clean while they are hot or cold but will not affect the surface finish.
I usually leave my iron castings in the sand for at least 3 hours to cool. That is because I want to be certain they have cooled to less than 900 degrees or so. Some of my castings weigh 55 pounds though they have quite a bit of surface area which allows them to them cool faster than if they were compact. My reason for cooling them in the sand is to reduce internal stresses as the US Navy did a study in 1948 that showed allowing castings to cool in the sand as opposed to hot shake-out reduced internal stresses. I have found my castings to be as warm as 500 degrees F after 3 hours in the sand. So, it seems prudent to wait that long. I think all crystal reorganization has been completed by the time the casting gets to 950 or so. I have not noted any change in burn-on of sand with late vs early shake-out. Sea coal in the sand, on the other hand, greatly reduces or eliminates burn on. Denis Denis
in the Navy in the 90s we let Cast Fe cool as long as possible, who wants to handle hot metal??? but both Billy and Dennis are 100% correct V/r HT1
