6/24/2023 0 Comments Datum reference frame![]() In order to manufacture and/or inspect a part to a drawing, the three (3) plane concept is necessary. ![]() The DRF is probably the most important concept of GD&T. The letter identifies the datum feature that is to be contacted however the letter in the FCF is the datum plane or axis of the datum simulators. The first letter is the primary datum, the second letter is the secondary datum, and the third letter is the tertiary datum. The desired order of precedence is obtained by entering the appropriate datum feature letter from left to right in the Feature Control Frame (FCF) (see Section 5 for explanation for FCF). Datum features have to be specifi ed in an order of precedence to properly position a part on the Datum Reference Frame. If the part has a circular feature that is identifi ed as the primary datum feature then as discussed later a datum axis is obtained which allows two (2) mutually perpendicular planes to intersect the axis which will be the primary and secondary datum planes.Īnother feature is needed (tertiary) to be contacted in order orientate (fi x the two planes that intersect the datum axis) and to establish the datum reference frame. Contacting the three (3) datum features simultaneously establishes the three (3) mutually perpendicular datum planes or the datum reference frame. ![]() The primary is the first feature contacted (minimum contact at 3 points), the secondary feature is the second feature contacted (minimum contact at 2 points), and the tertiary is the third feature contacted (minimum contact at 1 point). ![]()
0 Comments
Leave a Reply. |