we are casting grey cast Iron with DIZA machine.
recently we have faced a new defect as a surface hole and the hole is surrounded by a thin layer of nodular graphite.
the pictures from the defect are attached.
the number of this kind of defect in each of casting is less than 5 and generally less than 3.
does any one know what is the name of this defect?
do you have any previous on this defect?
How do I deal with it?
Thank you so much.
Dear Ghasem,
Can you tell me what the inoculation practice is? Are you using metal stream inoculation? What type of inoculant are you using?
A possible reason for the defect is contamination of the moulding sand by a magnesium or cerium containing inoculant.
So if you use metal stream inoculation, just blow off the spilled inoculant from the moulds after pouring. Your bigger problem is the contamination of the moulding sand.
Ragards,
Cor van Ettinger
I agree Cornelis´s suggestion et the moulding sand is contaminated with Mg or Ce maybe the sand is a mixed with the sand of Mg alloys
Cornelis Joannes van Ettinger
Dear Cornelis
We use stream inoculation.
I think you might be 100% right.
because we produce both ductile and grey iron with the same DISA machine.
The blowing of seems a very logical advice.
by spilled inoculant you mean those who splash over the sand mold due to failure in stream process that spread the inoculant over the mold and the Ferro silico magnesium particles that jump out of the reaction chamber during pouring (and lay over the mold?
Thank you so much
Dear Ghasem, if you do a kind of in-mold process on your Disa, you should not forget to remove the alloy of the non-cast or non-poured moulds!
I had the honor to work together with the inventor of the in-mould process Cliff Dunks. He told me the stories.😉
Cornelis Joannes van Ettinger
Dear Cornelis
here is the analysis of our sand by XRF. do you see anything (specially the MgO) unusual about it?
L.O.I . (determined at 900 C) : 9.6
Na2O: 0.8 wt.%
Fe2O3: 2.2 wt.%
MgO: 2.3 wt.%
Al2O3: 7.8 wt.%
K2O: 0.8 wt.%
SiO2: 75.1 wt.%
CaO: 1.1 wt.%
TiO2: 0.3 wt.%
P2O5: < 0.01 wt.%
SO3 < 0.01 wt.%
Cl< 0.01 wt.%
La & Lu < 0.01 wt.%
Dear Ghasem, I am not a specialist in moulding sands. Please try to get in contact with people of the company IMERYS or H.A. (Hüttenes Albertus)
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