Geometric Tolerances

The charts below give the Symbols for Geometric Tolerancing and Additional Symbols,

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.

Geometric dimensioning and tolerancing provides a comprehensive system for symbolically defining the geometrical tolerance zone.

GEOMETRIC TOLERANCE REFERENCE CHART - ASME Y14.5M And ISO/TC 213
TOLERANCE	CHARACTERISTIC	SYMBOL	DATUM NEEDED	APPLICABLE MODIFIERS (RMS, LMC, MMC)
FORM	STRAIGHTNESS		NO	LMC or MMC CAN APPLY TO FEATURE OF SIZE
FORM	FLATNESS		NO	DOES NOT APPLY
FORM	CIRCULARITY		NO	DOES NOT APPLY
FORM	CYLINDRICITY		NO	DOES NOT APPLY
PROFILE	LINE PROFILE		NO	DOES NOT APPLY
PROFILE	SURFACE PROFILE		NO	DOES NOT APPLY
ORIENTATION	PERPENDICULARITY		YES	LMC or MMC CAN APPLY TO FEATURE OF SIZE
ORIENTATION	ANGULARITY		YES	LMC or MMC CAN APPLY TO FEATURE OF SIZE
ORIENTATION	PARALLELISM		YES	LMC or MMC CAN APPLY TO FEATURE OF SIZE
LOCATION	SYMMETRY		YES	RFS ALWAYS
LOCATION	POSTIONAL		YES AND NO	LMC or MMC CAN APPLY TO FEATURE OF SIZE
LOCATION	CONCENTRICITY		YES	RFS ALWAYS
RUNOUT	CIRCULAR RUNOUT		YES	RFS ALWAYS
RUNOUT	TOTAL RUNOUT		YES	RFS ALWAYS

ADDITIONAL GEOMETRIC TOLERANCING SYMBOL CHART ASME Y14.5M And ISO/TC 213
DESCRIPTION	SYMBOLS	REFERENCES
MAXIMUM MATERIAL CONDITION (MMC)		ISO 2692/ASME
LEAST MATERIAL CONDITION (LMC)		ISO 2692/ASME
REGARDLESS OF SIZE FEATURE (RFS)		ISO/ASME
SPHERICAL DIAMETER (SD)		ISO/AMSE
RADIUS		ISO/ASME
DIAMETER		ISO/ASME
ENVELOPE REQUIREMENT		ISO/ASME
FREE STATE CONDITION (NON RIGID PARTS)		ISO 10579/ASME
MINOR DIAMETER		ISO/ASME
MAJOR DIAMETER		ISO/ASME
PITCH DIAMETER		ISO/ASME
COMMON ZONE		ISO/ASME
EXACT DIMENSION		ISO/ASME
DIMENSION ORIGIN		ISO/ASME
ALL ROUND (PROFILE)		ISO NONE/ASME
DATUM FEATURE INDICATION		ISO/ASME
DATUM TARGET INDICATION		ISO 5459
PROJECTED TOLERANCE ZONE		ISO 10578/ASME