Overview
ISO 2972:1979 - "Numerical control of machines - Symbols" defines a standardized set of graphical symbols for numerical control (N.C.) machine tools. Published by ISO/TC 97 (Computers and information processing), the second edition (1979) consolidates basic and compound symbols used to identify and display control functions on CNC/CAM systems and machine-tool control panels. The standard is specific to NC applications and refers users to ISO/R 369 for conventional machine-tool indication symbols.
Key Topics
- Basic symbols: directional arrow (two forms), functional arrow, data carrier, program (with and without machine functions), block, origin/datum, compensation/offset, store and interchange.
- Operational symbols: tape wind, forward/backward, continuous read, block-by-block execution, programmed stops and optional stops, block skip.
- Data and program handling: data carrier identification (paper tape, magnetic media), program begin/end, search functions, program alignment, program from external device, alternative data carrier input.
- Coordinate and positioning: reference position, coordinate origin, absolute vs incremental programming notation, zero offset, positioning accuracy (normal/coarse), programmed vs actual position, position (servo) error.
- Storage & editing: store/read/write/reset, program storage, subroutines and subroutine storage, buffer storage, program edit, modify/amend, repositioning.
- Errors and status: syntax/parity failure, storage overflow, storage error, battery indicator (IEC symbol referenced).
- Standardization notes: many compound symbols are formed from repeated basic symbols; arrow variants serve different semantic roles (directional vs functional).
Applications
ISO 2972:1979 is used to:
- Standardize control-panel graphics and operator displays for CNC machine tools.
- Ensure consistent symbols across machine manuals, training materials, and HMI interfaces.
- Improve operator comprehension, reduce errors, and support international interoperability of NC equipment.
- Guide designers of machine-tool controls, CNC manufacturers, technical illustrators, maintenance engineers, and documentation authors.
Who Should Use It
- Machine tool and CNC control manufacturers
- HMI and control panel designers
- Technical writers and documentation teams for machine tools
- Training providers and production engineers implementing CNC systems
- Standards committees and regulatory bodies harmonizing machine indications
Related Standards
- ISO/R 369 - Symbols for indications appearing on machine tools (referenced for conventional machine-tool symbols)
- IEC graphic symbols (battery symbol IEC 5001 referenced in the document)
Keywords: ISO 2972:1979, numerical control, NC symbols, CNC symbols, machine-tool symbols, control panel graphics, program symbols, data carrier, compensation, positioning accuracy.
