It is necessary today to hold precise tolerances to insure the interchangeability of parts
It's the process of determining the smount a dimension can vary from it's theorectical size
Basic Size
the exact theoretical size of a dimension
Tolerance
the amount a dimension can vary from basic size
Feature
used to identify the geometry of the drawing being referenced
Limits
the maximum and minimum allowable size
Allowance
the limits where the smallest clearance or largest interference occurs. Measured at MMC
Styles
Limit Dimensioning
Deviation Dimensioning
Symmetrical Dimensioning
MMC
(Maximum Material Condition)
The limit of a dimension where the max material is left on the part
LMC
(Least Material Condition)
the limit of a dimension where the least amount of material is left on the part
Type of Fit
Clearence (Running and Sliding Fit)
all dimension combos will produce clearence between parts
Interference
all combos of dimensions will produce a force fit
Transitional
different combos of dimensions will produce different kinds of fits