EN ISO 5455:1994

Overview

EN ISO 5455:1994 is an international standard developed by CEN that defines the recommended scales and their designations for use in technical drawings across all fields of engineering. Originally based on ISO 5455:1979, this standard provides clear definitions for different scale types-such as enlargement, full size, and reduction scales-and establishes guidelines for inscribing scale information on engineering drawings. Its consistent application ensures clarity, precision, and ease of interpretation in the representation of objects on technical documentation.

Key Topics

• Scale Definitions:

  • Scale: The ratio of the linear dimension of an element on a drawing to its actual size.
  • Full Size (1:1): The object is drawn at its actual size.
  • Enlargement Scales (e.g., 2:1, 5:1, 10:1, 20:1, 50:1): Drawings where the object is depicted larger than its real size.
  • Reduction Scales (e.g., 1:2, 1:5, 1:10, 1:20, down to 1:10,000): The object is shown smaller than actual size.

• Scale Designation and Inscription:

  • The scale used must be inscribed clearly, typically in the title block.
  • The designation includes the word “SCALE” (or its language equivalent) followed by the scale ratio (e.g., SCALE 1:1, SCALE 1:10).
  • When multiple scales appear on a single drawing, only the main scale goes in the title block. Secondary scales are identified near their related details or item references.

• Recommended Scales:
  The standard recommends using commonly accepted scales suitable for engineering drawings, allowing for extension by powers of ten when necessary (e.g., 1:1000 or 10:1). Custom intermediate scales are permitted only when functionally required and must derive logically from recommended values.

• Application to Detail Views:
  Small parts or complex details that are difficult to dimension clearly at the main scale should be shown in enlarged detail views, which are drawn at a larger scale adjacent to the main view.

• Large Scale Drawings:
  For objects represented at large scale, it is advised to add a simplified full size (1:1) outline view showing only the object’s shape to aid clear understanding.

Applications

• Engineering Design and Drafting:
  Ensures consistent scaling in mechanical, civil, electrical, and architectural drawings, allowing engineers and manufacturers to interpret dimensions accurately.

• Manufacturing and Quality Control:
  Precise scale designation helps manufacturers verify sizes and tolerances correctly, reducing errors due to misinterpretation of drawings.

• Technical Documentation:
  Widely adopted in technical manuals, assembly instructions, and maintenance guides where accurate representation of parts and assemblies is critical.

• International Collaboration:
  Facilitates clear communication across borders by standardizing scale usage and notation, essential in global engineering projects.

Related Standards

• ISO 128: General principles of presentation in technical drawings, complementing scale selection with drawing layout and symbols.
• ISO 129: Dimensioning rules for engineering drawings, aligned with scalable representations defined in EN ISO 5455.
• EN ISO 406: Signs and symbols for technical drawings, supporting clarity in scaled drawings.
• ISO 7200: Title block and document header layout standards, where scale inscriptions are typically placed.

By adhering to EN ISO 5455:1994, professionals ensure uniformity and precision in scale usage on technical drawings, enhancing the readability, reliability, and interoperability of engineering documents worldwide. This standard remains fundamental for engineers, drafting specialists, and quality inspectors aiming for accuracy and professionalism in technical representation.