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:
- 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.
Open preview (PDF)Mechanical pencils for technical drawings — Part 2: Black leads — Classification and dimensions