Determining Areas Used for Processing

In contrast to those surfaces on the workpiece which affect its function, other surfaces may be equally important in their effect on its manufacture. These surfaces influence the ease or difficulty with which the part can be located, supported, and held throughout the manufacturing sequence.

Some surfaces or areas have greater importance than other and are called critical areas. These are the ones which have a critical relationship with other areas on the workpiece and, as such, serve as registering points for the location system and can be identified from the part print. Identification can be made by looking for baselines from which dimensions are measured, close dimensional tolerances, and natural centerlines. The order of establishing processing areas is as follows :

1. Determine those areas best qualified for locating the workpiece during processing.

2. Determine those areas best qualified for supporting the workpiece during processing.

3. Determine those areas best qualified for holding the workpiece during processing.