Important Documents and standards

ISO TC 10 Technical product documentation

• ISO 128 Technical drawings – Indication of dimensions and tolerances
• ISO 7083 Symbols for geometrical tolerancing – Proportions and dimensions
• ISO 13715 Technical drawings – Edges of undefined shape – Vocabulary and indications
• ISO 15786 Simplified representation and dimensioning of holes
• ISO 16792:2015 Technical product documentation—Digital product definition data practices (Note: ISO 16792:2006 was derived from ASME Y14.41-2003 by permission of ASME)

ISO/TC 213 Dimensional and geometrical product    specifications and verification

In ISO/TR 14638 GPS – Masterplan the distinction between fundamental, global, general and complementary GPS standards is made.

• Fundamental GPS standards
  • ISO 8015 Concepts, principles and rules
• Global GPS standards
  • ISO 14660-1 Geometrical features
  • ISO/TS 17, orientation and location
  • ISO 1101 Geometrical tolerancing – Tolerances of form, orientation, location and run-out
    • Amendment 1 Representation of specifications in the form of a 3D model
  • ISO 1119 Series of conical tapers and taper angles
  • ISO 2692 Geometrical tolerancing – Maximum material requirement (MMR), least material requirement (LMR) and reciprocity requirement (RPR)
  • ISO 3040 Dimensioning and tolerancing – Cones
  • ISO 5458 Geometrical tolerancing – Positional tolerancing
  • ISO 5459 Geometrical tolerancing – Datums and datum systems
  • ISO 10578 Tolerancing of orientation and location – Projected tolerance zone
  • ISO 10579 Dimensioning and tolerancing – Non-rigid parts
  • ISO 14406 Extraction
  • ISO 22432 Features used in specification and verification
• General GPS standards: Areal and profile surface texture
  • ISO 1302 Indication of surface texture in technical product documentation
  • ISO 3274 Surface texture: Profile method – Nominal characteristics of contact (stylus) instruments
  • ISO 4287 Surface texture: Profile method – Terms, definitions and surface texture parameters
  • ISO 4288 Surface texture: Profile method – Rules and procedures for the assessment of surface texture
  • ISO 8785 Surface imperfections – Terms, definitions and parameters
  • Form of a surface independent of a datum or datum system. Each of them has a part 1 for the Vocabulary and parameters and a part 2 for the Specification operators:
    • ISO 12180 Cylindricity
    • ISO 12181 Roundness
    • ISO 12780 Straightness
    • ISO 12781 Flatness
  • ISO 25178 Surface texture: Areal
• General GPS standards: Extraction and filtration techniques
  • ISO/TS 1661 Filtration
  • ISO 11562 Surface texture: Profile method – Metrological characteristics of phase correct filters
  • ISO 12085 Surface texture: Profile method – Motif parameters
  • ISO 13565 Profile method; Surfaces having stratified functional properties

ASME standards

• ASME Y14.41 Digital Product Definition Data Practices
• ASME Y14.5 Dimensioning and Tolerancing
• ASME Y14.5.1M Mathematical Definition of Dimensioning and Tolerancing Principles

ASME is also working on a Spanish translation for the ASME Y14.5 – Dimensioning and Tolerancing Standard.

GD&T standards for data exchange and integration

• ISO 10303 Industrial automation systems and integration — Product data representation and exchange
  • ISO 10303-47 Integrated generic resource: Shape variation tolerances
  • ISO/TS 10303-1130 Application module: Derived shape element
  • ISO/TS 10303-1050 Application module: Dimension tolerance
  • ISO/TS 10303-1051 Application module: Geometric tolerance
  • ISO/TS 10303-1052 Application module: Default tolerance
  • ISO/TS 10303-1666 Application module: Extended geometric tolerance
  • ISO 10303-203 Application protocol: Configuration controlled 3D design of mechanical parts and assemblies
  • ISO 10303-210 Application protocol: Electronic assembly, interconnection, and packaging design
  • ISO 10303-214 Application protocol: Core data for automotive mechanical design processes
  • ISO 10303-224 Application protocol: Mechanical product definition for process planning using machining features
  • ISO 10303-238 Application protocol: Application interpreted model for computerized numerical controllers (STEP-NC)

Instroduction to 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 describe nominal geometry and its allowable variation. It tells the manufacturing staff and machines what degree of accuracy and precision is needed on each controlled feature of the part. GD&T is used to define the nominal (theoretically perfect) geometry of parts and assemblies, to define the allowable variation in form and possible size of individual features, and to define the allowable variation between features.

There are several standards available worldwide that describe the symbols and define the rules used in GD&T. One such standard is American Society of Mechanical Engineers (ASME) Y14.5. This article is based on that standard, but other standards, such as those from the International Organization for Standardization (ISO), may vary slightly. The Y14.5 standard has the advantage of providing a fairly complete set of standards for GD&T in one document. The ISO standards, in comparison, typically only address a single topic at a time. There are separate standards that provide the details for each of the major symbols and topics below (e.g. position, flatness, profile, etc.).

Origin of GD&T-

The origin of GD&T is credited to Stanley Parker, who developed the concept of "true position". While little is known about Parker's life, it is known that he worked at the Royal Torpedo Factory in Alexandria, West Dunbartonshire, Scotland. His work increased production of naval weapons by new contractors.

In 1940, Parker published Notes on Design and Inspection of Mass Production Engineering Work, the earliest work on geometric dimensioning and tolerancing. In 1956, Parker published Drawings and Dimensions, which became the basic reference in the field.