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revchrisThe undergrads at work have been playing in the foundry a lot lately, and one of the projects they need to work on is some bookends that have been promised to various people.
The bookend mold requires a sand core that is essentially made of epoxy-bonded sand and goes into a section of the mold where plain green sand wouldn't be strong enough to hold the necessary shape. It also requires a special mold for the core, which has taken us about six months to get back from the alumnus who had it.
Rachel (one of the undergrads) and I made our first two cores on Friday. They came out a lot harder than we expected, but we assumed that that was because we were using 2 weight percent resin, and the reference cores we were looking at were made by a different class and only used 1.5% resin.
I just took another look at the spreadsheet we were using. The way to convert from pounds to grams is not to multiply by 2.2 and then by 1,000; instead, it should be to divide by 2.2 and then multiply by 1,000 (or just multiply be 454.54). Our cores are brick-like because we used almost 5 times as much resin as the recipe calls for. This may not be bad, or the extra resin may give us problems when the metal hits it and things start to burn off.
The bookend mold requires a sand core that is essentially made of epoxy-bonded sand and goes into a section of the mold where plain green sand wouldn't be strong enough to hold the necessary shape. It also requires a special mold for the core, which has taken us about six months to get back from the alumnus who had it.
Rachel (one of the undergrads) and I made our first two cores on Friday. They came out a lot harder than we expected, but we assumed that that was because we were using 2 weight percent resin, and the reference cores we were looking at were made by a different class and only used 1.5% resin.
I just took another look at the spreadsheet we were using. The way to convert from pounds to grams is not to multiply by 2.2 and then by 1,000; instead, it should be to divide by 2.2 and then multiply by 1,000 (or just multiply be 454.54). Our cores are brick-like because we used almost 5 times as much resin as the recipe calls for. This may not be bad, or the extra resin may give us problems when the metal hits it and things start to burn off.
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no subject
Date: 2008-04-14 03:10 pm (UTC)no subject
Date: 2008-04-14 04:04 pm (UTC)We could, is suppose, fix it by specifying that we're having cost overrun problems and requesting additional funding, but since no one is giving us any money for this anyway, that really doesn't matter.