Cast iron?

The iron can burn and form more slag if the melt is going slower than expected, rotors tend have thin sections and a lot of surface area so they'd be prone to excess oxidation. I'd expect engine blocks to be the same being thin sections with a heavy layer of oxidation from the water jacket.

I do wonder about the composition of rotors, if there's other alloying elements that raise the melting point. The secret sauce for the Sheffield crucible steel makers was to put some crushed glass in the melt to protect the steel from burning. I might try that and see if it helps, also doing a bronze or aluminium melt first and then an iron melt could save some fuel and preheating time. Running a furnace for several hours makes each melt time go faster and faster with bronze at least, so saving the iron for when the furnace is nice and hot would reduce the slag.

 

I wonder if it was the last casting you poured with the defects?.

 

You know what this means?: always cast an extra in case of a failure!.

 

Hi
haven't been on site for some time, however, was reading some of the postings this morning
With the iron train wheels, feeding and shrinkage perhaps the riser of metal needs to be larger and closer to the Boss where you want to feed, this way the molten metal has better chance to feed the heavy section of casting your wanting to feed, the neck down part needs to be reduced in height so you have enough room to cut off the riser
Normally the propriety feeding materials (Hot tops) would have some filings of aluminium powder in the mix so it starts to kick off and ignite and therefore you get an exothermic reaction
However, suppose cost issues aside, you could look at something else which has insulating properties to at least cover the feeding riser,
In previously life we use to sell Perlite into the steelworks and use this as insulating cover on steel tundish prior to the continuous casting of steel
Perlite is also sold as s slag coagulant in iron/steel melting for deslagging, you could use this sparingly to remove some of oxides on the melt surface before you pour the casting and then hook the sheet of slag out of crucible so you reduce the contaminant and erosion on the inside wall of crucible, or it just keeps building for the subsequent pours
Perlite (raw, not expanded) should be available in bunnings (oil spills clean up), Horticulture as normally mixed with Vermiculite in potting mixes etc

On the fading and inoculant, I had a look on Foseco data base this morning for a general TDS on Inoculant which may help, and came across INOCULIN 320
1. chemistry, crushed FeSi generally 75%

2. addition rates of inoculant. Obliviously these Foseco inoculant are propriety products and have other stuff in there to help reduce fade, however, gives you some basic starting criteria
Addition rate:
GJL (cast Iron): 0,05 - 0,3 %
GJS (Ductile Iron): 0,1 - 0,5 %
Pipe Inoculation: 0,2 - 0,4 %

3. Grain size: for small crucibles: try and get the smallest sizing you can 0-3mm,
cheers Brett