Downloaded from https://www.everyspec.com ADS-43A-HDBK 2.2.2 Manufacturing Manufacturing includes all of the tasks associated with converting raw material, such as forging, castings, extrusions, millstock, powdered metallurgy, etc., into a finished part. Some generic critical characteristics in manufacturing include the following: A. Dimensions B. Tolerances C. Master tooling 1. Master gears 2. Master comparator charts D. Machining E. Grinding F. Honing G. Balancing 2.2.2.1 Justification for Manufacturing Critical Characteristics a . The dimensions of a part or component are variables that can be expressed as mass, density, length, area, volume, finish, or angle.
In some cases, when dealing with an assembly, moment or torque of a fastener is important. If any dimension is called out as a critical characteristic, it must be measured or verified on each part. For assemblies requiring interference or press fits, the dimensions of these parts cannot be verified after assembly, and must be measured before assembly. b . Allowable tolerances must be observed. Any requests for deviations must be dispositioned by a Material Review Board (MRB) and approved by USAATCOM engineering. Otherwise, by definition, any deviation from a critical dimensional tolerance on a critical part will be cause for rejection, unless the part can be reworked to print. c .
The intersection of bores for support of spiral bevel gears is a point in space. This makes verification of bore intersection accuracy very difficult. An automatic coordinate measuring machine can be used for this and other critical measurements. Other less accurate methods may be used if approved by USAATCOM engineering. Accurate measurement of bevel gear tooth surfaces can only be accomplished by a high quality coordinate measuring machine. Tooth patterns can be assessed by use of a marking dye or paste. This is a less accurate but acceptable method once a gear set has been tested and a pattern baseline established.
Master gears traceable to Grand or Gold Master Gears are required to measure tooth contact pattern on spiral bevel gears. d . Gear cases are usually line bored to insure parallel axes of gear shafts for spur or helical gear trains. Engine frame assemblies generally support main shaft bearings 1 3