Sigmetrix Mechanical Variation Management Blog

GD&T Symbols Reference Guide | Sigmetrix

Written by Sigmetrix Team | Jan 24, 2024 4:24:00 PM

In geometric dimensioning and tolerancing (GD&T), a unique set of GD&T symbols are used to define the relationships between part features and measurement references. Designers and engineers utilize this international language on their drawings to accurately describe part features on the basis of size, form, orientation and location.

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  • Understands what the GD&T means
  • Understands how the GD&T works
  • Understands the effect of the GD&T on product function, manufacturing, inspection, and assembly
  • Understands the effects of the GD&T throughout the product lifecycle

We ensure that your design, manufacturing, inspection, assembly, quality, and service personnel and your suppliers understand GD&T as needed to be successful and produce the highest quality, lowest cost products possible.

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To download your copy of the free GD&T Symbols Reference Guide, please click here.

 

GD&T Symbol Control Type Name Summary Description

 

Form Straightness Controls the straightness of a feature in relation to its own perfect form

 

Form Flatness Controls the flatness of a surface in relation to its own perfect form

 

Form Circularity Controls the form of a revolved surface in relation to its own perfect form by independent cross sections

 

Form Cylindricity Like circularity, but applies simultaneously to entire surface

 

Profile Profile of a Surface Controls size and form of a feature. In addition it controls the location and orientation when a datum reference frame is used.

 

Profile Profile of a Line Similar to profile of a surface, applies to cross sections of a feature

 

Orientation Perpendicularity Controls the orientation of a feature which is nominally perpendicular to the primary datum of its datum reference frame

 

Orientation Angularity Controls orientation of a feature at a specific angle in relation to the primary datum of its datum reference frame

 

Orientation Parallelism Controls orientation of a feature which is nominally parallel to the primary datum of its datum reference frame

 

Location Position Controls the location and orientation of a feature in relation to its datum reference frame

 

Location Concentricity Controls concentricity of a surface of revolution to a central datum

 

Location Symmetry Controls the symmetry of two surfaces about a central datum

 

Runout Circular runout Controls circularity and coaxiality of each circular segment of a surface independently about a coaxial datum

 

Runout Total runout Controls circularity, straightness, coaxiiality, and taper of a cylindrical surface about a coaxial datum

Our GD&T Advisor software solution provides the automation you need to make manual GD&T methods a thing of the past!

Sigmetrix’ unique, state-of-the-art solution accelerates the design process, saving valuable time, and reduces the manufacturing costs like scrap and change orders, saving thousands of dollars every year. Each of our expertly designed software programs the internationally recognized GD&T Symbols throughout the modeling and reporting processes.

Symbol Meaning
LMC –
Least Material Condition

 

MMC –
Maximum Material Condition

 

Tangent Plane

 

Projected Tolerance Zone

 

Free State

 

Diameter

 

Radius

 

Spherical Radius

 

Spherical Diameter

 

Controlled Radius

 

Statistical Tolerance

 

Basic Dimension

 

Reference Dimension

 

Places
 
Symbol Meaning

 

Dimension Origin

 

Counterbore

 

Countersink

 

Depth

 

All Around

 

Between

 

Target Point

 

Conical Taper

 

Slope

 

Square

 

Sigmetrix is premier source for tolerance analysis and design optimization software, training, and engineering solutions. For more information about GD&T Advisor software or any of our tolerance analysis solutions and services, contact us at info@sigmetrix.com or  via our website here.