Some manufacturing processes, such every bit casting, forging, welding, in addition to oestrus treating, are probable to create uneven or irregular surfaces. Datum targets may live on used to immobilize parts amongst such uneven or irregular surfaces. Datum targets may also live on used to back upwards irregular-shaped parts that are non easily mounted inwards a datum reference frame. Datum targets are used alone when necessary because, in 1 trial they are specified, costly manufacturing in addition to inspection tooling is required to procedure them.
Datum targets are designed to contact parts at specific points, lines, in addition to areas. These datum targets are ordinarily referenced from 3 mutually perpendicular planes to flora a datum reference frame. Influenza A virus subtype H5N1 principal datum plane is established yesteryear a minimum of 3 datum targets non inwards a conduct line. Two datum targets are used to flora a secondary datum plane. And 1 datum target establishes a 3rd datum plane. Influenza A virus subtype H5N1 combination of datum target points, lines, in addition to areas may live on used. Datum target points are represented on a drawing yesteryear target betoken symbols in addition to identified yesteryear datum target symbols such every bit datum targets B1 in addition to B2 shown inwards Figure.
Actual tooling points on the fixture are non points at all but pins amongst hemispherical ends contacting the role amongst the highest betoken on the hemisphere, every bit shown inwards Figure. Influenza A virus subtype H5N1 datum target business is represented yesteryear a target betoken symbol on the border of the role inwards the transcend persuasion of the drawing in addition to yesteryear a phantom business on the front end view, datum target C1. Since datum target C1 is on the far side of the part, a dashed radial business is used to connect the datum target symbol. Where a datum target expanse is required, the desired expanse is outlined yesteryear a phantom business in addition to filled amongst department lines, every bit shown for datum targets A1, A2, in addition to A3. All datum targets are dimensioned for place in addition to size either yesteryear toleranced dimensions or basic dimensions. Basic dimensions are toleranced amongst gage-makers’ tolerances.
Note that A1, A2, A3 are datum target areas in addition to B1, B2 are datum target points in addition to C1 is datum target line.