GB/T 39542.3-2020
AbolishedMechanical pencils for technical drawings—Part 3: Black leads—Bending strengths of HB leads
技术制图活动铅笔 第3部分：黑铅芯 HB铅芯弯曲强度
Application Summary AI generated
This standard specifies the test method and minimum bending strength requirements for HB black leads used in mechanical pencils for technical drawings. It is applied by manufacturers and quality control labs to ensure leads meet durability standards for precise, consistent line work in engineering, architectural, and design drafting. The standard is relevant to the production and testing of 0.5 mm, 0.7 mm, and other common lead diameters used in technical drawing pencils.
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Transparency note: The application summary and key sentences on this page were automatically generated by AI from the standard's original text. This content has not been human-verified and should not be used for compliance or regulatory purposes. Always refer to the official standard document from the issuing authority.