Position Error (shown in Fig.3-2): is the variation of the actual position of related factors to its ideal position form. Companies want across-the-board savingsįorm Error (shown in Fig.3-1): is the variation of the true form of a single factor to its perfect form make a small shaft found to be distortion and not cylindrical, or the section is out of round, or the axes is bended, or make a plane found to be warp.

It is important to increase productivity.

It is important to reduce drawing changes.

It is important to stop scrapping perfectly good parts.

Features are critical to function or interchangeability.

Drawing delineation and interpretation need to be the same.

Designers should tolerance parts with the form and position tolerances when

Because form and position tolerances were designed to position size features, the simplest answer is, locate all size features with form and position tolerances controls. Many designers ask under what circumstances they should use the form and position tolerances. When Should Form and Position Tolerances Be Used? Drawings with properly applied geometric tolerance provide the best opportunity for uniform interpretation and cost-effective assembly. Features toleranced with the form and position tolerances reflect the actual relationship between mating parts. What is form and position tolerances? Form and position tolerances is used to specify the shape, form, orientation, and location of features on a part.

Circular runout general tolerances