ISO GPS specification. ST - Requirements applied to micro and macrogeometry of products

Dimensional, geometric, surface condition, and transition specifications are symbolic tools indicated in Technical Product Documentation (TPD – ) via 2D definition drawings of parts or via a specified 3D model (3D specification annotation) in order to transcribe the expected functions on or in the system.

It should be noted that the term "design drawing" in the rest of this article is understood to be equivalent to TPD (whether paper or digital, 2D or 3D).

An industrial part is defined by design offices to perform specific functions at an optimal cost price.

Based on functional specifications, the designer chooses technical solutions. This is followed by the definition of the overall system design, then the detailed designs of its components.

These design drawings are communication tools that enable the design office to describe its expectations to other departments (manufacturing, measurement, purchasing, etc.).

Based on a design drawing, the manufacturing methods departments can determine the most suitable manufacturing process(es) for producing the requested part with the support of the quality control and measurement department, which itself defines the optimal measurement or control processes to ensure that the product complies with all the requirements specified in the definition drawing, either directly or indirectly through the use of general specifications or by referring to documents requiring the application of specific requirements.

It is also thanks to this definition drawing that the purchasing department can consult suppliers.

The definition drawing contains various pieces of information:

• the nominal geometry of the part;

• nominal dimensions;

• the material;

• the requirements described, among other things, through dimensional, geometric, or surface condition specifications.

This set of information communicates what is expected of the parts and implies a cost of acquisition.

This article aims to present the dimensional, geometric, and surface finish specifications and the links between the various stakeholders within the company. In summary, the technical stakeholders seek to perform functions through product specifications, minimizing their acquisition costs (design, manufacturing, control, logistics, etc.).