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.

(GD&T) 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  Symbols Control Type

 Description

Straightness FORM Where an component of a surface is a straight line
 Flatness FORM

Surface having all elements in one plane

Circularity FORM The form of surface of revolution (cone, Cylinder, Sphere) where all points of the surface intersected by any plane.
Cylindricity FORM Like circularity, but applies simultaneously to the entire part of the surface.

 Profile of a line

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

 Profile of a surface

PROFILE Uniform amount of profile variation, either unilaterally or bilaterally, along a line element of a surface.
Perpendicularity ORIENTATION Which is 90 deg perpendicular to the primary datum of its datum reference frame.
Angularity ORIENTATION Which is having specific angle in relation to the primary datum of its datum reference frame.
Parallelism ORIENTATION Which is having a equidistant at all points from datum plane.
Position LOCATION Orientation of a features relation to its  datum reference frame.
Concentricity LOCATION In which two or more features having a same axis.
Symmetry LOCATION Symmetry of two planes about a center datum.

 Circular run out

RUNOUT Circularity 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).