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Geometric Tolerances In Product Design

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Geometric tolerances- Geometric dimensioning and tolerancing (GD&T)  is a system for defining and communicating  engineering tolerances . It uses a symbolic language on  engineering drawings  and computer-generated three-dimensional solid models that explicitly describes nominal  geometry  and its allowable variation. It tells the manufacturing staff and machines what degree of  accuracy and precision  is needed on each controlled feature of the part. GD&T is used to define the nominal (theoretically perfect) geometry of parts and assemblies, to define the allowable variation in form and possible size of individual features, and to define the allowable variation between features. All Over Specification [ASME Y14.5-2009 Section 8.3.1.6]  - In addition to a general profile of a surface tolerance there is the option of specifying that the tolerance applies all over on the field of the drawing. It is important to realize that this specification, whether in a general note or on the