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If You Design Molded, Cast or Forged Parts, You Should Be Using the Y14.8 Standard!
(In accordance with the ASME Y14.5-2009 standard)

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A lot of folks think that the only source of tolerancing is the Y14.5 standard.  However, if you design, produce or inspect cast, forged or molded parts, you should include the ASME Y14.8-2009 standard in your reference library.  These parts share similar characteristics that create challenges for dimensioning and tolerancing.  Some of these include draft, parting lines, flash, mis match, and the list goes on.  The Y14.8 standard contains several symbols that enable dimensioning and tolerancing while taking these process effects into consideration.  The Standard also defines many terms as they relate to these processes.

Allowing for draft is often confusing and misinterpreted.  Y14.8 standardizes methods for dimensioning draft.  Holding tolerances on the side of a parting line is nearly always easier than holding tolerances across or on the other side of a parting line.  The symbols for parting line, all around this side of parting line and all over this side of parting line make it easy to account for such variation.  The movable datum target symbol originated in this standard and is now used in several other American and ISO standards.

Although the engineering drawing must capture the design intent of the part it is essential that the drawing also account for the unavoidable variations caused by the manufacturing process. By utilizing the ASME Y14.8-2009 standard, the drawing can capture design intent while allowing for process variation of cast, forged and molded parts.

Back to Tips Tip added Jan 2013