Tuesday, 26 May 2020
ENGINEERING CONCEPTS

Geometric Dimensioning and Tolerance (GD&T) Symbols

  • Geometrical Dimensioning and Tolerance is language of accurately communicate geometry requirement for associated features on assembly and individual manufacturing component drawings.
  • GD&T consist of dimensioning, tolerances, symbols, definition, rules and it is used for precisely communicate the functional requirements for the location, orientation, size, and form of each feature of the design models.
GDT-Symbols
GDT-Symbols

 

  • GD&T symbols provides accurate dimension from point to point of requirement of model. Manufacturing of the drawing having concise of GD&T symbols to help of understanding the drawing.
Name of the  SymbolsControl Type

 Description

StraightnessFORMWhere an component of a surface is a straight line
 FlatnessFORM

Surface having all elements in one plane

CircularityFORMThe form of surface of revolution (cone, Cylinder, Sphere) where all points of the surface intersected by any plane.
CylindricityFORMLike circularity, but applies simultaneously to the entire part of the surface.

 Profile of a line

PROFILEUniform amount of profile variation, either unilaterally or bilaterally, along a line element of a feature.

 Profile of a surface

PROFILEUniform amount of profile variation, either unilaterally or bilaterally, along a line element of a surface.
PerpendicularityORIENTATIONWhich is 90 deg perpendicular to the primary datum of its datum reference frame.
AngularityORIENTATIONWhich is having specific angle in relation to the primary datum of its datum reference frame.
ParallelismORIENTATIONWhich is having a equidistant at all points from datum plane.
PositionLOCATIONOrientation of a features relation to its  datum reference frame.
ConcentricityLOCATIONIn which two or more features having a same axis.
SymmetryLOCATIONSymmetry of two planes about a center datum.

 Circular run out

RUNOUTCircularity and co-axiality of each circular segment of a surface independently about a center datum
Total run out

RUNOUT

Circularity, straightness, co – axiality and taper of a cylindrical surfaces about a center datum to rotated 360(deg).