TS ISO 9177-2

TS ISO 9177-2 is the standard for the classification and dimensions of black leads used in mechanical pencils for technical drawings. It provides a common way to identify the lead types and their dimensional designations, supporting consistent use of writing and drawing components in technical drafting.

How the lead types are classified

The standard identifies two kinds of black leads: polymer leads, designated by the letter “P”, and ceramic leads, designated by the letter “C”. This distinction matters because the lead material influences how the lead behaves in use and how it is selected for drafting applications. In general technical terms, polymer leads represent the familiar lead formulations used in many mechanical pencils, while ceramic leads indicate a different material family with its own performance profile.

What the dimensional rules are for

This standard establishes a dimensional framework for black leads so that measurements such as diameter, length, or related size attributes can be understood consistently under the same designation system. In technical drawing, lead size affects compatibility with the pencil mechanism as well as the resulting line character. As general technical context, lead geometry can influence line width, wear behaviour, and the feel of writing or drawing.

• Applies to black leads used in mechanical pencils for technical drawings.
• Distinguishes two lead types: P and C.
• Covers classification and dimensions of the leads.
• Supports consistent identification of leads used in drafting practice.