- May 4, 2015
I spent a few years machining cast iron , so much so when I sweat it was rusty. Took quite awhile to get rid of it in my system. Even breathing got better after changing jobs. But it taught me how to machine the cast iron , you can get spots that are so hard even your carbide will skin over it. You can try varying your feed rate . But there's carbide which is graded for cast iron , if your castings so close to size there not using the right shrink measurements for cast iron . Molding has different measurements for casting different metals. If there using the same form for different metals then the mold builder is at fault. I forget all the formulas for different metals . But I know if your casting is to close there at fault. I'd bet there using the same form for aluminum. Or even the heat of the metal when cast can cause hard spots. I think it can be annealled if I remember correctly. Sometimes they cool to quickly and harden up. There's a real knack or science to casting metals. Cast iron being a tuff one to master. Probally why there aren't any foundries like there use to be. I don't even know if the US pipe in NJ is still.operating. I received several very lucrative job offers from them but after seeing the castings I was to machine I stayed in the shop building missiles . Fun work not dark and dirty.