ISO 5455:1979

Overview

ISO 5455:1979 is an international standard developed by the International Organization for Standardization (ISO) that provides guidelines for the use of scales in technical drawings across all fields of engineering. The standard establishes recommended scales and their correct designation for clear and consistent communication in engineering drawings. By adhering to this standard, engineers, drafters, and designers ensure precise representation of physical objects, facilitating accurate interpretation and reducing errors in manufacturing, construction, and other technical disciplines.

Key Topics

• Scale Definition
  The ratio of the linear dimension on the drawing compared to the real object. ISO 5455 defines:

  • Full size scale (1:1): Actual size representation.
  • Enlargement scales (>1:1): Enlarged representation of small parts for clarity (e.g., 2:1, 5:1, 10:1).
  • Reduction scales (<1:1): Reduced representation of large objects (e.g., 1:2, 1:5, 1:1000).

• Recommended Scale Values
  The standard lists widely accepted scales ranging from large-scale enlargements like 50:1 to small-scale reductions as tiny as 1:10,000. These scales can be extended by powers of ten for special cases or intermediate scales may be used when necessary.

• Designation and Inscription
  Scales must be clearly indicated on technical drawings to avoid misinterpretation. The designation format is:

  • SCALE 1:X for reductions,
  • SCALE X:1 for enlargements, and
  • SCALE 1:1 for full-size drawings.

  The scale inscription is mandatory in the drawing's title block, and multiple scales on a drawing require only the main scale in the title block, with supplementary scales assigned to corresponding detail views.

• Application of Multiple Scales
  Where detailed parts are too small for clear dimensioning at the main scale, a separate enlarged detail view should be created, each labeled with its scale for clarity.

Applications

ISO 5455:1979 is vital for industries and professionals involved in technical and engineering drawings, including:

• Mechanical Engineering: Accurately depicting machine components that vary widely in scale.
• Civil Engineering and Architecture: Presenting large-scale site plans alongside detailed view of components or structural details.
• Electrical and Electronic Design: Enlarging small circuit elements while maintaining overall layout clarity.
• Manufacturing and Fabrication: Assisting machinists and fabricators in understanding exact part sizes and details through standardized scales.
• Education and Training: Establishing foundational knowledge about scale usage in technical drawings for students and apprentices.

By following this standard, professionals ensure that every stakeholder can easily understand and work with drawings-minimizing errors and streamlining the design-to-production process.

Related Standards

• ISO 128 - Technical Drawings - General Principles of Presentation
• ISO 128-23 - Technical Drawings - Lines on Mechanical Engineering Drawings
• ISO 1101 - Geometrical Product Specifications - Geometrical Tolerancing
• ISO 7200 - Technical Product Documentation - Data Fields in Title Blocks and Document Headers

These related standards complement ISO 5455 by covering broader aspects of technical drawing presentation, dimensioning, and documentation, creating a comprehensive framework for engineering documentation.

Keywords: ISO 5455, technical drawing scales, engineering scales, scale designation, enlargement scale, reduction scale, full size scale, technical documentation standards, engineering drawings standard, international standard scales