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:

    “Many older wealthy families have learned to instill a sense of public service in their offspring. But newly affluent middle-class parents have not acquired this skill. We are using our children as symbols of leisure-class standing without building in safeguards against an overweening sense of entitlement—a sense of entitlement that may incline some young people more toward the good life than toward the hard work that, for most of us, makes the good life possible.”
    —David Elkind (20th century)

    “There are those who would keep us slipping back into the darkness of division, into the snake pit of racial hatred, of racial antagonism and of support for symbols of the struggle to keep African-Americans in bondage.”
    —Carol Moseley-Braun (b. 1947)

    “Luckless is the country in which the symbols of procreation are the objects of shame, while the agents of destruction are honored! And yet you call that member your pudendum, or shameful part, as if there were anything more glorious than creating life, or anything more atrocious than taking it away.”
    —Savinien Cyrano De Bergerac (1619–1655)