Small questions about ductile iron and casting conditions

What kind of data do larger foundries generally store? Composition of every melt? Thermal history of each casting? Quality variables?
What are the main quality parameters for castings of ductile iron (spheroidal graphite iron)? Sorry if I am using poor terminology - I have heard these terms mostly in the local language here.
What variables affect nodularity significantly? Thermal history can contain several variables (or one can consider the whole temperature-time profile), but presumably only three-four thermal variables could be significant. In one example, I have seen three GRFs. It seems they are calculated based on empirical equations, and am wondering if it would not be better to only include the composition instead of GRFs. Do all GRFs improve nodularity?
What are the main causes of rejects (castings not meeting specifications)? Poor nodularity? What can they do to reduce rejects? I am trying to find out if I can correlate some quality variables with thermal history and composition, which can help reduce rejects.
Thanks for any information.
With kind regards,
A. Bulsari
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I service a few spectrometers and a mate of mine (G'day Simon!) on this group will probably see this and add a few comments.
Like: What's the difference between a metalurgist and a computer? You have to punch information into both of them, but with a computer you only have to do it once!
The chemical composition is regularly stored as part of the normal spectrometer software operation, with sample analysis time and date recorded automatically and this is often combined with a few extra fields on the same computer system. These may include: Leco result pour temperature time of pour weight in furnace operator name job or route card number other various sample identity fields to suit local foundry operations can be added with most of the software systems from most manufacturers also offering spc software options (that cost more $).
The same thing can be done with a 49 cent exercise book, a pencil, a couple of sheets of graph paper and a "little bit of time". This is possibly the quickest way to see what sort of information you need to use for your operation. It will certainly take less time than it will to learn how to use the software package!
I tend to think that the more information you have to work with, the better. If you have stored the info, you have a chance to find a trend. You might find that you want to compare the difference between different sands or all sorts of strange variables.
Hope this helps, Peter

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Thanks for this information.
>I service a few spectrometers and a mate of mine (G'day Simon!) on this >group will probably see this and add a few comments. > >Like: What's the difference between a metalurgist and a computer? You have >to punch information into both of them, but with a computer you only have to >do it once! > >The chemical composition is regularly stored as part of the normal >spectrometer software operation, with sample analysis time and date recorded >automatically and this is often combined with a few extra fields on the same >computer system. These may include: >Leco result
What is a Leco result? I find that Leco is a company which manufactures devices for foundries, but can't figure out what measurements they are.
>pour temperature >time of pour >weight in furnace >operator name >job or route card number >other various sample identity fields to suit local foundry operations can be >added with most of the software systems from most manufacturers also >offering spc software options (that cost more $).
Does SPC help? If you consider the effects of variables like GRF, their effects seem to be quite clearly nonlinear, and even the linear component of which may not be extracted correctly by linear regression. Is it easy to carry out planned experiments? I think not.
> >The same thing can be done with a 49 cent exercise book, a pencil, a couple >of sheets of graph paper and a "little bit of time". This is possibly the >quickest way to see what sort of information you need to use for your >operation. It will certainly take less time than it will to learn how to use >the software package! > >I tend to think that the more information you have to work with, the better. >If you have stored the info, you have a chance to find a trend. You might >find that you want to compare the difference between different sands or all >sorts of strange variables. > >Hope this helps, >Peter
Could you also comment on the other questions? Thanks,
With kind regards,
A. Bulsari
>
> >> What kind of data do larger foundries generally store? Composition of >> every melt? Thermal history of each casting? Quality variables? >> >> What are the main quality parameters for castings of ductile iron >> (spheroidal graphite iron)? Sorry if I am using poor terminology - I >> have heard these terms mostly in the local language here. >> >> What variables affect nodularity significantly? Thermal history can >> contain several variables (or one can consider the whole >> temperature-time profile), but presumably only three-four thermal >> variables could be significant. In one example, I have seen three >> GRFs. It seems they are calculated based on empirical equations, and >> am wondering if it would not be better to only include the composition >> instead of GRFs. Do all GRFs improve nodularity? >> >> What are the main causes of rejects (castings not meeting >> specifications)? Poor nodularity? What can they do to reduce rejects? >> I am trying to find out if I can correlate some quality variables with >> thermal history and composition, which can help reduce rejects. >> >> Thanks for any information. >> >> With kind regards, >> >> A. Bulsari >

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Leco results refer to the measurements made by Leco carbon/sulfur determinators. Analysis of carbon by optical spectroscopy (OES) in the range for irons (~3-4%) can be very error-prone. The best method of determining carbon is by direct measurement- combustion of a sample of iron, measuring the amount of CO2 produced. The Leco determinator will give a readout in %C, very accurate! Sulfur contents can be determined at the same time, but in my experience, the results from OES vs Leco agree fairly well for sulfur in irons.
Regards, Mike Malone
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