huangyhg

die mismatch
according to asme y14.8, 3.13, mismatch, where applicable, shall be specified as a maximum value. mismatch may exceed perfect form boundary at mmc, unless otherwise noted.
if the mismatch is not listed in the notation of the casting drawing, does this bind the castor to meeting the dimensional tolerances across the parting line, or is a mismatch value added by default of the nature of the process?
the mismatch would not be added by default to tolerances. i would set up and measure per drawing per drawing. mismatch could be a cause for a dimension being nonconforming.
dave d.
i too would agree with your last paragraph weavedreamer. if you don't specify mismatch then the part should meet whatever other tolerances you do spec.
if this is an issue & they needed extra mismatch tolerance the casting house should have brought it up when they quoted. i've just had this issue with a forge, they didn't ask for extra mismatch initially but now are adding +-.03 extra.
kenat,
i agree with dave and i would agree with the first option of paragraph two
quote:
does this bind the castor to meeting the dimensional tolerances across the parting line
yes it does unless otherwise stated in the tolerance specifications.
paul
yeah, sorry i meant i agree with the first part of your second paragraph.
kenat,
thanks.
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