Geometric Dimensioning and Tolerancing - Symbols

Symbols

Tolerances: Type of Tolerances; 1) Unilateral 2) Bi- Lateral type

Geometric tolerancing reference chart
Type of tolerance Geometric characteristics Symbol Can be applied to a feature? Can be applied to a feature of size? Can affect virtual condition? Datum reference used? Can use
modifier?		 Can use
modifier?		 Can be affected by a bonus tolerance? Can be affected by a shift tolerance?
Form Straightness
Yes Yes Yes
 No Yes
 No
 Yes
 No
Form Planarity
Yes No No No No No
 No No
Form Circularity
Yes No No No No No
 No No
Form Cylindricity
Yes No No No No No
 No No
Profile Profile of a line
Yes No No Yes
 No No
 No Yes
Profile Profile of a surface
Yes No No Yes
 No No
 No Yes
Orientation Perpendicularity
Yes Yes Yes
 Yes Yes
 No
 Yes
 Yes
Orientation Angularity
Yes Yes Yes
 Yes Yes
 No
 Yes
 Yes
Orientation Parallelism
Yes Yes Yes
 Yes Yes
 No
 Yes
 Yes
Location Symmetry
?
 ?
 ?
 ?
 ?
 ?
 ?
 ?
Location Positional Tolerance
No Yes Yes Yes Yes Yes Yes
 Yes
Location Concentricity
No Yes Yes Yes No No
 No No
Runout Circular runout
Yes Yes Yes
 Yes No No
 No No
Runout Total runout
Yes Yes Yes
 Yes No No
 No No

Notes:

  1. When applied to a feature-of-size.
  2. Can also be used as a form control without a datum reference.
  3. When a datum feature-of-size is referenced with the MMC modifier.
  4. When an MMC modifier is used.
  5. Automatic per rule #3.
  6. The symmetry symbol's characteristics were not included in the version of the chart that this chart is derived from. The symmetry symbol was dropped from the Y14.5M standard around 1988 and re-added around 1994.
Symbol Modifier
Free state
Least material condition (LMC)
Maximum material condition (MMC)
Projected tolerance zone
Regardless of feature size (RFS)
Tangent plane
Unilateral

Notes:

  1. The symbol is not part of the 1994 version. See para. A5, bullet 3. Also para. D3. Also, Figure 3-8.
  2. The symbol appears in the 2009 version of the standard, and refers to unequal profile distribution.
  3. All the symbols above are used in a feature control frame to specify a feature's description, tolerance, modifier and datum references.

Read more about this topic:  Geometric Dimensioning And Tolerancing

Famous quotes containing the word symbols:

    “For all symbols are fluxional; all language is vehicular and transitive, and is good, as ferries and horses are, for conveyance, not as farms and houses are, for homestead.”
    —Ralph Waldo Emerson (1803–1882)

    “Children became an obsessive theme in Victorian culture at the same time that they were being exploited as never before. As the horrors of life multiplied for some children, the image of childhood was increasingly exalted. Children became the last symbols of purity in a world which was seen as increasingly ugly.”
    —C. John Sommerville (20th century)

    “I do not deny that there may be other well-founded causes for the hatred which various classes feel toward politicians, but the main one seems to me that politicians are symbols of the fact that every class must take every other class into account.”
    —José Ortega Y Gasset (1883–1955)