Tolerancias Geometricas

According to the ASME Y14.5-2009[1] standard, the purpose of geometric dimensioning and tolerancing (GD&T) is to describe the engineering intent of parts and assemblies. This is not a completelycorrect explanation of the purpose of GD&T or dimensioning and tolerancing in general.
The purpose of GD&T is more accurately defined as describing the geometric requirements for part and assemblygeometry. Proper application of GD&T will ensure that the allowable part and assembly geometry defined on the drawing leads to parts that have the desired form and fit (within limits) and function asintended.
There are some fundamental rules that need to be applied (these can be found on page 6 of the 2009 edition of the standard):
All dimensions must have a tolerance. Every feature on everymanufactured part is subject to variation, therefore, the limits of allowable variation must be specified. Plus and minus tolerances may be applied directly to dimensions or applied from a general toleranceblock or general note. For basic dimensions, geometric tolerances are indirectly applied in a related Feature Control Frame. The only exceptions are for dimensions marked as minimum, maximum, stock orreference.
Dimensioning and tolerancing shall completely define the nominal geometry and allowable variation. Measurement and scaling of the drawing is not allowed except in certain cases.Engineering drawings define the requirements of finished (complete) parts. Every dimension and tolerance required to define the finished part shall be shown on the drawing. If additional dimensions would behelpful, but are not required, they may be marked as reference.
Dimensions should be applied to features and arranged in such a way as to represent the function of the features.
Descriptions ofmanufacturing methods should be avoided. The geometry should be described without explicitly defining the method of manufacture.
If certain sizes are required during manufacturing but are not required in...