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These standards have been approved by the American National Standards Institute and adopted by the Department of Defense, aircraft industry, automotive industry, heavy construction equipment, agriculture equipment and many other commercial enterprises. The Y14.5 standard is the most widely accepted standard of geometric tolerancing and dimensioning for mechanical devices. When drawings are based on this standard, the methods of dimensioning and tolerancing shall be in accordance with ASME Y14.5 and this standard. This standard was first published in 1989 and has been revised to the current 2009 revision. They are best known for setting codes and standards for mechanical devices. The American Society of Mechanical Engineers (ASME) was founded in 1880 and has more than 120,000 members in more than 150 countries worldwide. The ASME standard Y14.8 covers definitions of terms and features unique to casting, forging and molded part technologies with recommendations for their uniform specification on engineering drawings and related documents. Surfaces are not flat and have many imperfections, holes are not round they have draft, sinks, voids and many other problems, most surfaces perpendicular to the mold parting plane have draft, in other words tapered, edges at parting lines have various unconventional conditions created from finishing operations, thus proper descriptions can be challenging. So what is unique about parts produced from these processes? They can be considered a glob of material. Castings, Forgings and Molded parts by nature are very non-uniform and special considerations must be made when specifying their requirements, such as process allowances and dimensioning and tolerancing.
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Parts produced by any process do not have prefect form, prefect form does not exist. This is a tool that can greatly improve communicating the specifications for producing and qualifying parts that are produced by casting, forging or molding.