What is true position GD&T?

GD&T uses a notion called True Position when tolerancing locations. There are two forms of True Position–one for a feature size under a material condition (Maximum Material Condition or Least Material Condition), and one for True Position Regardless of Feature Size (RFS).
A.

What is the position tolerance?

Position Tolerance (symbol: ?) is a geometric dimensioning and tolerancing (GD&T) location control used on engineering drawings to specify desired location, as well as allowed deviation to the position of a feature on a part.
  • What is meant by tolerance of form?

    Form Tolerance - A form tolerance states how far an actual surface is permitted to vary from desired geometric form. Expressions of these tolerances refer to limits of size, flatness, straightness, parallelism, perpendicularly, angularity, roundness, cylindricity, profile of a surface and profile of a line.
  • What is the symbol of flatness?

    GD&T Flatness is very straight forward. It is a common symbol that references how flat a surface is regardless of any other datum's or features. It comes in useful if a feature is to be defined on a drawing that needs to be uniformly flat without tightening any other dimensions on the drawing.
  • What is the parallel?

    an imaginary circle on the earth's surface formed by the intersection of a plane parallel to the plane of the equator, bearing east and west and designated in degrees of latitude north or south of the equator along the arc of any meridian. the line representing this circle on a chart or map.
B.

What is GD&T tolerance?

Geometric Dimensioning and Tolerancing (GD&T) is a system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models that explicitly describes nominal geometry and its allowable variation.
  • What is MMC and LMC?

    MMC is the condition of a feature which contains the maximum amount of material, that is, the smallest hole or largest pin, within the stated limits of size. LMC is the condition in which there is the least amount of material, the largest hole or smallest pin, within the stated limits of size.
  • What is GD&T?

    Geometric Dimensioning and Tolerancing (GD&T) is a system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models that explicitly describes nominal geometry and its allowable variation.
  • What is GDT used for?

    GD&T stands for Geometric Dimensioning and Tolerancing. It is a system of symbols, rules and definitions used to define the geometry of mechanical parts. GD&T is one of the most powerful tools available that can improve quality, reduce cost and shorten delivery time.
C.

What is MMC and LMC?

MMC is the condition of a feature which contains the maximum amount of material, that is, the smallest hole or largest pin, within the stated limits of size. LMC is the condition in which there is the least amount of material, the largest hole or smallest pin, within the stated limits of size.
  • What is LMC of a hole?

    Definition: Least material condition is a feature of size symbol that describes a dimensional or size condition where the least amount of material (volume/size) exists within its dimensional tolerance. The callout also overrides GD&T Rule#2 or the Regardless of Feature Size rule.
  • What is a feature of size?

    In GD&T the term feature-of-size (FOS) refers to any surface, or set of parallel surfaces associated with a size dimension. Specific examples of features of size include: A hole diameter (a cylindrical surface) Plate thickness (two opposed parallel surfaces)
  • What is the meaning of material condition?

    Definition: Maximum Material Condition or for short, MMC, is a feature of size symbol that describes the condition of a feature or part where the maximum amount of material (volume/size) exists within its dimensional tolerance.

Updated: 25th September 2018

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