Overview - ISO 14638:2015 (Geometrical product specifications - Matrix model)
ISO 14638:2015 is a fundamental ISO GPS (Geometrical Product Specification) standard that defines a universal matrix model for organizing and understanding the ISO GPS system. It provides a framework to show how current and future ISO GPS standards relate to one another, the extent of their scope, and how to structure development of GPS standards by ISO/TC 213. ISO 14638:2015 is intended for users of GPS standards-designers, manufacturers, metrologists and standards developers-who need a clear map of which standards cover which geometrical properties and which stages of specification, measurement and verification.
Key topics and technical content
- Matrix structure: Rows represent the nine geometrical property categories; columns represent the standard “chain links” that span specification to verification.
- Nine geometrical properties covered in the model:
- Size, Distance, Form, Orientation, Location, Run‑out
- Profile surface texture, Areal surface texture, Surface imperfections
- Seven chain links (each chain describes elements required for a complete GPS standard):
- Symbols and indications
- Feature requirements
- Feature properties
- Conformance and non‑conformance
- Measurement
- Measurement equipment
- Calibration
- Datums: Clause 4 explains how datum standards are treated (datums are not counted as geometrical properties but are addressed within the matrix model).
- Principles for standards development: Guidance and recommendations for drafting GPS standards so they interoperate and avoid conflicts (references include ISO 8015 and default decision rules of ISO 14253‑1).
Practical applications and users
ISO 14638:2015 is a practical reference for:
- Design and mechanical engineers creating toleranced drawings and CAD specifications.
- Quality and metrology teams defining measurement methods, equipment requirements, and calibration strategies.
- Standards developers and technical committees (ISO/TC 213) organizing new GPS standards or updating existing ones.
- Procurement and compliance groups mapping conformance requirements across supply chains.
- Tooling/CAM integrators and inspection labs aligning verification procedures with specification intent.
Use cases:
- Identifying which ISO GPS standards to apply for a given geometric characteristic (e.g., size of cylinders, form tolerances).
- Structuring internal quality processes to cover specification → measurement → calibration steps.
- Harmonizing product documentation (TPS/TPD) with the ISO GPS system.
Related standards
- ISO 8015 - Fundamental rules for GPS (decision rules)
- ISO 14253‑1 - Decision rules for verification (default decision rules referenced)
- ISO/TC 213 - Technical committee responsible for GPS standards and the matrix model
ISO 14638:2015 is essential when you need a comprehensive, standards‑level view of how geometrical specification, measurement and conformity fit together across the ISO GPS ecosystem.
