ISO 9177-2:2022

Overview

ISO 9177-2:2022 - Mechanical pencils for technical drawings - Part 2: Black leads - Classification and dimensions specifies the classification, nominal diameters and standard lengths for black leads used exclusively in mechanical pencils intended for technical drawing. The standard defines two lead types: polymer leads (P) and ceramic leads (C), and sets requirements that support consistent line quality, interchangeability and clear product designation.

Key topics

• Types of black leads: Polymer (designated “P”) and ceramic (designated “C”).
• Hardness degree: Standardized hardness scale runs from soft (6B) to hard (9H), with HB as the median. Hardness availability varies with nominal diameter (smaller diameters cover a narrower hardness range).
• Nominal diameters: Standard diameters include 0.25 mm, 0.35 mm, 0.5 mm, 0.7 mm, 1 mm, (1.4 mm noted) and 2 mm. Note: common market labels like 0.3 and 0.9 correspond to 0.35 and 1 mm respectively.
• Standard lengths: Typical standardized lead lengths include 60 mm, 90 mm, 100 mm, 30 mm, 45 mm, 25 mm, and 130 mm; actual length depends on the pencil mechanism and nominal diameter.
• Designation format: Packaging and product marking should follow the prescribed format:
  • Example polymer: Black lead ISO 9177-2-P-0,5-60
  • Example ceramic: Black lead ISO 9177-2-C-2-130
• Normative references: Cross-references include ISO 128-2 (line conventions) and ISO 9177-1 (classification, dimensions, performance and testing for mechanical pencils).

Applications

• Ensures interchangeability of leads across mechanical pencils used for technical drawings in architecture, engineering and drafting.
• Helps manufacturers and suppliers define product specifications, labeling and quality control for black leads.
• Assists specifiers, procurement teams and design studios in selecting leads by diameter, hardness and type for predictable line thickness and erasability.
• Useful for standards compliance, product development and technical documentation where consistent drawing materials are required.

Related standards

• ISO 9177-1 - Mechanical pencils for technical drawings: classification, dimensions, performance requirements and testing.
• ISO 128-2 - Technical product documentation: basic conventions for lines.
• ISO 20318 series - Mechanical pencils and leads for general use (classification, dimensions, quality and test methods).

Keywords: ISO 9177-2, mechanical pencils for technical drawings, black leads, polymer leads, ceramic leads, lead diameters, lead lengths, hardness degree, lead designation.