GD&T (Geometric Dimensioning and Tolerancing) tolerance refers to the allowable variation or deviation specified on a geometric dimension or feature of a part or component. GD&T is a system used in engineering and manufacturing to define and communicate the allowable tolerances for the form, size, orientation, and location of features on a part.
In GD&T, tolerance is represented using specific symbols, modifiers, and measurement criteria. These symbols and modifiers are used to precisely define the tolerance zone within which the feature must lie in order to be considered acceptable. The tolerance zone defines the maximum allowable deviation from the ideal or perfect form of the feature.For example, a straightness tolerance might be specified as 0.1 mm. This means that the feature being measured must not deviate more than 0.1 mm from a perfectly straight line. Similarly, a positional tolerance might be specified as ±0.05 mm. This means that the feature’s location must fall within a tolerance zone of ±0.05 mm relative to a specified datum reference.
GD&T tolerances provide a standardized and precise way to communicate the desired tolerances for different features on a part. By specifying tolerances using GD&T, manufacturers can ensure that parts are produced within the acceptable range of variation, leading to better quality control, interchangeability of parts, and effective assembly of components.
History of GD&T Tolerance
The history of Geometric Dimensioning and Tolerancing (GD&T) dates back to the early 1940s. Here’s a brief overview of its development and evolution:
1.Origins And Early Standards:
GD&T emerged as a response to the need for more precise and standardized methods of specifying tolerances in manufacturing.
The concept of GD&T was initially introduced by Stanley Parker, an engineer at the Royal Torpedo Factory in Alexandria, Virginia, during World War II.
The early development of GD&T was influenced by the works of Dr. Walter Shewart, who is known for his contributions to statistical quality control and control charts.
2.Early Publications And Standards:
In the 1950s, George R. Holmes, an engineer at the U.S. Army’s Frankford Arsenal, began publishing articles on GD&T in various technical journals.
In 1956, the American Society of Mechanical Engineers (ASME) published the first standard on GD&T, known as ASME Y14.2, which introduced the basic symbols and concepts of GD&T.
3.Evolution and Expansion:
Over the following decades, GD&T evolved and expanded as new standards were developed to address different aspects of geometric tolerancing.
In 1966, ASME released the first edition of the Y14.5 standard, which provided a comprehensive system for geometric dimensioning and tolerancing.
Subsequent revisions and updates to the ASME Y14.5 standard were made to refine and clarify the GD&T concepts, symbols, and practices.
In the 1990s, the International Organization for Standardization (ISO) developed its own set of GD&T standards, known as ISO 1101 and related standards.
4.Modern GD&T Practices:
GD&T has become an integral part of the design and manufacturing processes in various industries, including automotive, aerospace, defense, and electronics.
Advances in computer-aided design (CAD) and metrology technologies have facilitated the application and implementation of GD&T in modern manufacturing.
The latest revisions of the ASME Y14.5 and ISO 1101 standards continue to refine and expand the GD&T system, addressing new challenges and incorporating industry best practices.
Today, GD&T is widely used globally as a standardized language for specifying and controlling tolerances, ensuring consistency, interoperability, and quality in the design, production, and inspection of mechanical parts and assemblies.
The Benefits Of GD&T Tolerance
Geometric Dimensioning and Tolerancing (GD&T) offers several benefits in the design, manufacturing, and inspection processes. Here are some key advantages of using GD&T:
- Precise Communication: GD&T provides a precise and standardized language to communicate design requirements and tolerances. It eliminates ambiguity and misinterpretation, ensuring clear communication between designers, manufacturers, and inspectors.
- Enhanced Design Functionality: GD&T allows designers to define tolerances based on the function and fit of parts, rather than relying solely on simple linear dimensions. This enables more robust and functional designs while accommodating manufacturing variations.
- Improved Quality Control: GD&T ensures better quality control by specifying allowable tolerances in a comprehensive manner. It enables manufacturers to accurately produce parts within the specified tolerances, reducing rework, scrap, and assembly issues.
- Interchangeability and Assembly: GD&T promotes interchangeability of parts and ease of assembly. By precisely defining tolerances and dimensional relationships, GD&T facilitates the assembly of components from different suppliers, leading to improved manufacturing efficiency.
- Cost Savings: GD&T can result in cost savings by optimizing tolerances. By specifying tighter tolerances only where necessary, manufacturers can reduce manufacturing costs, as well as the time and resources spent on inspection and rework.
- Enhanced Inspection and Quality Assurance: GD&T provides clear guidelines for inspection and quality assurance processes. It allows inspectors to measure and verify parts against defined tolerances using appropriate inspection methods, reducing errors and improving quality assurance.
- Global Standardization: GD&T is an internationally recognized standard. It enables seamless communication and collaboration between different stakeholders across the globe, facilitating the exchange of design data and manufacturing information.
- Improved Supplier Relations: GD&T helps foster better relationships between manufacturers and suppliers. By providing precise tolerances and requirements, GD&T reduces disputes and ensures that suppliers can meet the specified quality standards consistently.
- Compliance with Regulatory Standards: In industries with strict regulatory requirements, such as aerospace and automotive, GD&T assists in compliance with regulatory standards. It ensures that parts and assemblies meet the necessary specifications and perform reliably.
GD&T offers numerous benefits in terms of improved communication, quality control, cost savings, assembly efficiency, and global standardization. It is a powerful tool for achieving better product quality, reliability, and consistency in various manufacturing industries.
GD&T Tolerance Symbols
Certainly! Here’s a table of some commonly used GD&T tolerance symbols along with their corresponding definitions:
| Symbol | Name | Definition |
|---|---|---|
| ⌖ | Straightness | The allowable deviation from a true straight line for a feature such as a line, axis, or center plane. |
| ⌓ | Flatness | The allowable variation in the flatness of a surface. |
| ⭕ | Circularity | The allowable variation in the roundness of a circular feature. |
| ⌕ | Cylindricity | The allowable variation in the form of a cylindrical feature. |
| ‖ | Parallelism | The allowable deviation between two parallel features. |
| ⊥ | Perpendicularity | The allowable deviation from a true 90-degree angle for features such as surfaces, lines, or axes. |
| ⩾ | Angularity | The allowable deviation from a specified angle or angular relationship between features. |
| ⌖ | Position | The allowable deviation in the location of a feature relative to a datum reference or a specified coordinate system. |
| ⌸ | Concentricity | The allowable deviation between two coaxial features, ensuring they have a common center axis. |
| ⌔ | Profile of a Line | The allowable variation in the shape of a line. |
| ⌒ | Profile of a Surface | The allowable variation in the shape of a surface. |
| ⌙ | Runout | The allowable variation in the circularity or straightness of a feature as it rotates or moves. |
| ⌗ | Total Runout | The combined allowable variation in all geometric aspects of a feature as it rotates or moves. |
| Ø | Diameter | Specifies the diameter of a cylindrical feature. |
| ♀ | Radius | Specifies the radius of a curved feature. |
Documents And Standards
Geometric Dimensioning and Tolerancing (GD&T) is governed by various documents and standards that provide guidelines for its application. The most widely recognized standards for GD&T are published by the American Society of Mechanical Engineers (ASME) and the International Organization for Standardization (ISO). Here are the key documents and standards related to GD&T:
- ASME Y14.5: This is the primary standard for GD&T in the United States. The current version is ASME Y14.5-2018, titled “Dimensioning and Tolerancing.” It provides detailed guidelines, symbols, rules, and practices for specifying and interpreting GD&T.
- ISO 1101: This is the primary GD&T standard published by the International Organization for Standardization (ISO). ISO 1101 provides international guidelines for dimensioning and tolerancing. The latest version is ISO 1101:2021, titled “Geometrical product specifications (GPS) – Geometrical tolerancing – Tolerances of form, orientation, location, and runout.”
- ASME Y14.5.1: This standard, titled “Mathematical Definitions of Dimensioning and Tolerancing Principles,” complements the ASME Y14.5 standard by providing mathematical and computational definitions and explanations of key concepts used in GD&T.
- ISO/TS 17450 series: This series of technical specifications developed by ISO covers various aspects of GD&T. Notable specifications include ISO/TS 17450-1:2012 (formerly ISO 5459:2011) on “Geometrical product specifications (GPS) – Geometrical tolerancing – Datums and datum systems” and ISO/TS 17450-2:2012 (formerly ISO 10578:1992) on “Geometrical product specifications (GPS) – Geometrical tolerancing – Maximum material requirement (MMR), least material requirement (LMR), and reciprocity requirement (RPR).”
- ASME Y14 series: Apart from ASME Y14.5, the ASME Y14 series includes several related standards and guidelines that address specific aspects of dimensioning and tolerancing, such as ASME Y14.3 for multi-view and sectional view drawings and ASME Y14.36 for surface texture symbols.
- GD&T Training Materials: Various organizations and institutions offer training materials, books, and courses on GD&T. These resources provide in-depth explanations, practical examples, and exercises to help individuals learn and apply GD&T effectively.
It’s important to consult the specific standards and documents relevant to your industry and region to ensure compliance and proper application of GD&T principles. The ASME and ISO standards mentioned above are widely recognized and adopted internationally, providing a solid foundation for GD&T implementation in various industries.
14 Different Tolerances Specific to GD&T Use
1.Angularity Definitions
GD&T Angularity tolerance controls the allowable deviation from a specified angle or angular relationship between features. Here are two common definitions associated with Angularity:
- Angularity of a Line: The Angularity tolerance for a line specifies the maximum permissible angle by which the line can deviate from its specified orientation. It ensures that the line remains within a specified angular tolerance zone.
- Angularity of a Surface: The Angularity tolerance for a surface specifies the allowable deviation in the orientation of the surface relative to a specified reference axis or plane. It controls the angular relationship between the surface and the reference feature within the specified tolerance zone.
In both cases, the Angularity tolerance is specified using the ⩾ symbol, followed by the tolerance value or limit. The tolerance value represents the maximum permissible angular deviation from the specified orientation.
It’s important to note that the specific application and context of Angularity tolerance may vary depending on the design requirements and the feature being evaluated. The tolerance zone for Angularity can be defined as a parallel-sided space or a cylindrical space depending on the needs of the application.
By using Angularity tolerance, designers and manufacturers can ensure that features such as lines and surfaces are within the specified angular requirements, enabling proper fit, function, and assembly of components.
2.Perpendicularity Definitions
GD&T Perpendicularity tolerance controls the allowable deviation from a true 90-degree angle for features such as surfaces, lines, or axes. It ensures that the specified feature is perpendicular to the datum reference or the specified orientation within a specified tolerance zone.
The Perpendicularity tolerance is represented using the ⊥ symbol. Here is the definition of Perpendicularity:
Perpendicularity: The Perpendicularity tolerance specifies the maximum allowable deviation in orientation from a true 90-degree angle for a feature. It ensures that the feature remains perpendicular to the datum reference or the specified orientation within a specified tolerance zone.
The Perpendicularity tolerance is typically associated with surfaces, lines, or axes, and it ensures that these features are oriented at right angles to the reference or specified direction within the specified tolerance zone.
By using Perpendicularity tolerance, designers and manufacturers can ensure the proper alignment and function of components, particularly when it is crucial for features to be perpendicular to each other for effective assembly, mating, or functionality.
3.Cylindricity Definition
GD&T Cylindricity tolerance controls the allowable variation in the form of a cylindrical feature. It ensures that the surface of the cylindrical feature remains within a specified tolerance zone, maintaining its circularity and straightness along its length.
The Cylindricity tolerance is represented using the ⌕ symbol. Here is the definition of Cylindricity:
Cylindricity: The Cylindricity tolerance specifies the maximum allowable variation in form of a cylindrical feature, ensuring that the surface remains within a specified tolerance zone. It combines the requirements for circularity and straightness along the entire length of the cylindrical feature.
The Cylindricity tolerance assesses the deviation of the actual surface of the cylinder from the perfect theoretical cylinder. It considers both the circularity (deviation from a perfect circle) and straightness (deviation from a perfectly straight line along the axis) of the cylindrical feature.
By specifying Cylindricity tolerance, designers and manufacturers can ensure the desired form and quality of cylindrical features, such as shafts, bores, or pins. This tolerance ensures proper fit, functionality, and interchangeability of cylindrical components, particularly when there is a need for precise cylindrical shape and alignment within the specified tolerance zone.
4.Position Definition
GD&T Position tolerance is a widely used tolerance that controls the allowable deviation in the location of a feature relative to a specified datum reference or a specified coordinate system. It defines a tolerance zone within which the center plane, axis, or feature of interest must lie.
The Position tolerance is represented using the ⌖ symbol. Here is the definition of Position:
Position: The Position tolerance specifies the maximum allowable deviation in the location of a feature relative to a specified datum reference or coordinate system. It establishes a tolerance zone that the feature must conform to, ensuring its positional accuracy.
The Position tolerance considers both the magnitude (the maximum allowable deviation in distance) and the orientation (the angular deviation) of the feature from its true position. It is typically used to control the location of features such as holes, slots, and other geometric entities.
The Position tolerance is specified with a tolerance value that represents the maximum permissible deviation from the specified position. It may also be accompanied by additional modifiers and control frames to provide more specific instructions and requirements.
By using Position tolerance, designers and manufacturers can ensure the proper location and alignment of features, enabling effective assembly, mating, and functional requirements. It provides a precise and standardized way to communicate the desired location of features, ensuring consistency and interoperability in manufacturing processes.
5.Runout Definition
GD&T Runout tolerance is used to control the allowable variation in the circularity or straightness of a feature as it rotates or moves. It specifies a tolerance zone that the feature must remain within while rotating or moving.
The Runout tolerance is represented using the ⌙ symbol. Here is the definition of Runout:
Runout: The Runout tolerance specifies the maximum allowable deviation in the circularity or straightness of a feature as it rotates or moves. It establishes a tolerance zone that the feature must conform to, ensuring its positional and form accuracy during rotation or movement.
Runout can be of two types:
- Total Runout (Tolerance Zone): Total Runout specifies the combined allowable variation in all geometric aspects (including form, orientation, and location) of a feature when it rotates or moves. It controls the cumulative effect of all other individual tolerances on the feature.
- Circular Runout (Tolerance Zone): Circular Runout specifies the allowable variation in the circularity of a feature as it rotates. It ensures that the circular feature remains within a specified tolerance zone during rotation.
Runout tolerance is often used for features like cylindrical surfaces, shafts, or rotating components where concentricity and true circularity are critical.
The Runout tolerance is typically specified with a tolerance value that represents the maximum permissible deviation from the specified circularity or straightness. It may also be accompanied by additional modifiers and control frames to provide more specific instructions and requirements.
By using Runout tolerance, designers and manufacturers can ensure the proper form, alignment, and functionality of rotating or moving features, minimizing issues such as vibration, misalignment, or excessive runout that could impact performance or reliability.
6.Total Runout Definition
GD&T Total Runout tolerance, also known as Total Runout Tolerance Zone, is a tolerance that specifies the combined allowable variation in all geometric aspects (including form, orientation, and location) of a feature as it rotates or moves. It controls the cumulative effect of all other individual tolerances on the feature.
Total Runout is represented using the ⌗ symbol. Here is the definition of Total Runout:
Total Runout: The Total Runout tolerance specifies the maximum allowable deviation in the circularity, straightness, form, orientation, and location of a feature as it rotates or moves. It establishes a tolerance zone that encompasses all possible deviations of the feature during rotation or movement.
Total Runout considers both the circularity (deviation from a perfect circle) and straightness (deviation from a perfectly straight line along the axis) of the feature, as well as other geometric aspects. It provides an overall assessment of the feature’s variation and ensures that it remains within the specified tolerance zone during rotation or movement.
Total Runout tolerance is typically used for features like cylindrical surfaces, rotating components, or parts that require precise alignment and concentricity.
The Total Runout tolerance is specified with a tolerance value that represents the maximum permissible deviation from the specified criteria. It may also be accompanied by additional modifiers and control frames to provide more specific instructions and requirements.
By using Total Runout tolerance, designers and manufacturers can ensure the proper overall form, alignment, and functionality of rotating or moving features, minimizing issues such as excessive runout, misalignment, or improper fit that could affect performance or reliability.
7.Profile of a Line Definition
GD&T Profile of a Line tolerance controls the allowable variation in the shape of a line. It ensures that the actual profile of the line remains within a specified tolerance zone, ensuring its form and ensuring that it does not deviate beyond the specified boundaries.
The Profile of a Line tolerance is represented using the ⌔ symbol. Here is the definition of Profile of a Line:
Profile of a Line: The Profile of a Line tolerance specifies the maximum allowable deviation in the shape of a line. It ensures that the entire profile of the line remains within a specified tolerance zone, ensuring its form and preventing any portion of the line from extending beyond the specified boundaries.
The Profile of a Line tolerance considers the variation in the contour of the line, including any deviations from straightness, smoothness, or any other specified criteria along its entire length.
The Profile of a Line tolerance is typically used to control the shape and accuracy of features such as edges, slots, or other linear entities.
The Profile of a Line tolerance is specified with a tolerance value that represents the maximum permissible deviation from the true shape. It may also be accompanied by additional modifiers and control frames to provide more specific instructions and requirements.
By using the Profile of a Line tolerance, designers and manufacturers can ensure the proper form, straightness, and shape of lines, ensuring that they meet the desired requirements and function effectively within the specified tolerance zone.
8.Parallelism Definition
GD&T Parallelism tolerance controls the allowable deviation between two parallel features. It ensures that the specified features remain parallel within a specified tolerance zone, maintaining a consistent distance and alignment along their entire length.
Parallelism tolerance is represented using the ‖ symbol. Here is the definition of Parallelism:
Parallelism: The Parallelism tolerance specifies the maximum allowable deviation between two parallel features, such as surfaces, lines, or axes. It ensures that the features remain parallel within a specified tolerance zone, maintaining a consistent distance and alignment along their entire length.
Parallelism tolerance is commonly used when it is critical for features to be parallel to each other for proper assembly, functionality, or alignment requirements.
The Parallelism tolerance is specified with a tolerance value that represents the maximum permissible deviation between the parallel features. It may also be accompanied by additional modifiers and control frames to provide more specific instructions and requirements.
By using Parallelism tolerance, designers and manufacturers can ensure the proper alignment, fit, and functionality of components that require parallelism. This tolerance ensures that the parallel features maintain the desired relationship, minimizing issues such as interference, misalignment, or inconsistent contact surfaces.
9.Straightness Definition
GD&T Straightness tolerance controls the allowable deviation in the form of a feature, ensuring that it remains straight within a specified tolerance zone. It defines the maximum permissible departure from a perfectly straight line or surface along the specified feature.
Straightness tolerance is represented using the ⇐⇒ symbol. Here is the definition of Straightness:
Straightness: The Straightness tolerance specifies the maximum allowable deviation from a perfectly straight line or surface for a feature. It ensures that the feature remains within a specified tolerance zone, maintaining its straight form.
Straightness tolerance can be applied to various features such as lines, surfaces, axes, or profiles that need to maintain straightness throughout their entire length or extent.
The Straightness tolerance is specified with a tolerance value that represents the maximum permissible deviation from perfect straightness. It may also be accompanied by additional modifiers and control frames to provide more specific instructions and requirements.
By using Straightness tolerance, designers and manufacturers can ensure the desired straight form and alignment of features, ensuring proper fit, functionality, and interchangeability of components. This tolerance helps minimize issues such as misalignment, bending, or warping that could affect the performance or integrity of the part.
10.Concentricity Definition
GD&T Concentricity tolerance controls the allowable deviation between the center points of two or more features. It ensures that the center points of the features are aligned and share a common axis within a specified tolerance zone.
Concentricity tolerance is represented using the ⊙ symbol. Here is the definition of Concentricity:
Concentricity: The Concentricity tolerance specifies the maximum allowable deviation between the center points of two or more features, such as circles, cylinders, or coaxial surfaces. It ensures that the center points remain aligned and share a common axis within a specified tolerance zone.
Concentricity tolerance is different from Position tolerance as it specifically focuses on the alignment of center points rather than the entire feature. It is particularly relevant when ensuring the coaxiality of features or when the functional requirements demand the concentric alignment of rotating or interacting components.
The Concentricity tolerance is specified with a tolerance value that represents the maximum permissible deviation between the center points of the features. It may also be accompanied by additional modifiers and control frames to provide more specific instructions and requirements.
By using Concentricity tolerance, designers and manufacturers can ensure the proper alignment, fit, and functionality of components that require concentricity. This tolerance ensures that the center points of features remain aligned, minimizing issues such as eccentricity, imbalance, or misalignment that could affect the performance or reliability of the part.
11.Flatness Definition
GD&T Flatness tolerance controls the allowable variation in the flatness of a surface. It ensures that the surface remains within a specified tolerance zone, maintaining its flatness and preventing excessive waviness or curvature.
Flatness tolerance is represented using the ⌓ symbol. Here is the definition of Flatness:
Flatness: The Flatness tolerance specifies the maximum allowable deviation of a surface from a perfectly flat plane. It ensures that the surface remains within a specified tolerance zone, maintaining its flatness and preventing excessive waviness or curvature.
Flatness tolerance is typically applied to surfaces, such as mating surfaces, mounting surfaces, or reference surfaces, where a high degree of flatness is required for proper fit, contact, or alignment.
The Flatness tolerance is specified with a tolerance value that represents the maximum permissible deviation of the surface from a perfect plane. It may also be accompanied by additional modifiers and control frames to provide more specific instructions and requirements.
By using Flatness tolerance, designers and manufacturers can ensure the desired flatness of surfaces, ensuring proper fit, contact, and functionality of components. This tolerance helps minimize issues such as uneven mating, interference, or misalignment that could impact the performance or reliability of the part or assembly.
12.Symmetry Definition
GD&T Symmetry tolerance controls the allowable variation in the symmetry of a feature relative to a datum or a specified axis. It ensures that the feature is symmetrically distributed around the reference axis or plane within a specified tolerance zone.
Symmetry tolerance is represented using the ∽ symbol. Here is the definition of Symmetry:
Symmetry: The Symmetry tolerance specifies the maximum allowable deviation in the symmetry of a feature relative to a datum or a specified axis. It ensures that the feature is symmetrically distributed around the reference axis or plane within a specified tolerance zone.
Symmetry tolerance is typically applied to features that require bilateral symmetry, such as profiles, cross-sections, or symmetrically shaped components. It ensures that the feature is evenly distributed and balanced on both sides of the reference axis or plane.
The Symmetry tolerance is specified with a tolerance value that represents the maximum permissible deviation from perfect symmetry. It may also be accompanied by additional modifiers and control frames to provide more specific instructions and requirements.
By using Symmetry tolerance, designers and manufacturers can ensure the desired bilateral symmetry of features, ensuring proper balance, aesthetics, and functionality of components. This tolerance helps minimize issues such as asymmetry, uneven distribution of mass, or misalignment that could affect the performance or appearance of the part or assembly.
13.Circularity Definition
GD&T Circularity tolerance controls the allowable deviation from a perfectly circular form for a feature. It ensures that the feature remains within a specified tolerance zone, maintaining its circularity and preventing excessive out-of-roundness.
Circularity tolerance is represented using the ○ symbol. Here is the definition of Circularity:
Circularity: The Circularity tolerance specifies the maximum allowable deviation from a perfect circle for a feature. It ensures that the feature remains within a specified tolerance zone, maintaining its circular form and preventing excessive out-of-roundness.
Circularity tolerance is typically applied to features such as circular bores, holes, or cylindrical surfaces where maintaining circularity is critical for proper fit, alignment, or rotational requirements.
The Circularity tolerance is specified with a tolerance value that represents the maximum permissible deviation from a perfect circle. It may also be accompanied by additional modifiers and control frames to provide more specific instructions and requirements.
By using Circularity tolerance, designers and cnc machining manufacturers can ensure the desired circularity of features, ensuring proper fit, alignment, and functionality of components. This tolerance helps minimize issues such as eccentricity, wobbling, or interference that could affect the performance or reliability of the part or assembly.
14.Profile of a Surface Definition
GD&T Profile of a Surface tolerance controls the allowable variation in the shape, contour, and orientation of a surface within a specified tolerance zone. It ensures that the actual surface profile remains within the specified boundaries, maintaining its form, orientation, and overall characteristics.
Profile of a Surface tolerance is represented using the ⊢ symbol. Here is the definition of Profile of a Surface:
Profile of a Surface: The Profile of a Surface tolerance specifies the maximum allowable deviation in the shape, contour, and orientation of a surface. It ensures that the entire surface profile remains within a specified tolerance zone, maintaining its form and preventing any portion of the surface from extending beyond the specified boundaries.
The Profile of a Surface tolerance considers the overall variation of the surface, including any deviations from flatness, curvature, or other specified criteria. It provides a comprehensive assessment of the surface’s deviation from the true shape and establishes a tolerance zone that encapsulates all possible deviations.
Profile of a Surface tolerance is commonly used to control the form, contour, and fit of surfaces that interact with other components or play a critical role in the functionality of a part or assembly.
The Profile of a Surface tolerance is specified with a tolerance value that represents the maximum permissible deviation from the true surface profile. It may also be accompanied by additional modifiers and control frames to provide more specific instructions and requirements.
By using Profile of a Surface tolerance, designers and manufacturers can ensure the proper form, contour, and alignment of surfaces, ensuring optimal fit, functionality, and interchangeability of components. This tolerance helps minimize issues such as interference, misalignment, or inconsistent contact surfaces that could impact the performance or reliability of the part or assembly.