Standard No.:	GB/T 43550.2-2023
English Name:	Mechanical pencils and leads for general use—Classification|| dimensions|| quality and test methods—Part 2: Black leads
Chinese Name:	一般用途活动铅笔和铅芯 分类、尺寸、质量和试验方法 第2部分：黑铅芯
Chinese Classification:	Y50    Culture, education and drawing instruments, notebooks and cards
Professional Classification:	GB    National Standard
Source Content Issued by:	SAMR; SAC
Issued on:	2023-12-28
Implemented on:	2023-12-28
Status:	valid
Target Language:	English
File Format:	PDF
Word Count:	7500 words
Translation Price(USD):	225.0
Delivery:	via email in 1~3 business day

Mechanical pencils and leads for general use - Classification, dimensions, quality and test methods - Part 2: Black leads 1 Scope This document specifies classification, dimensions, quality and test methods for black leads used for mechanical pencils for general writing, as specified in ISO20318-1. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document, For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO5-3:2009 Photography and graphic technology - Density measurements - Part 3: Spectral conditions Note: GB/T 11501-2008, Photography - Density measurement - Part 3: Spectral conditions (ISO 5-3:1995, IDT) ISO 12757-1 Ball point pens and refills - Part 1: General use Note: GB/T 32017-2019, Roller ball pens and refills (ISO 14145-1:2017; ISO 14145-2:1998, MOD) ISO 14145-1 Roller ball pens and refills - Part 1: General useISO20318-1, Mechanical pencils for general use - Classification, dimensions, quality and testingmethods - Part 1: Mechanical pencils Note: GB/T 6113.104-2021, Specification for radio disturbance and immunity measuring apparatus and methods - Part 1-4: Radio disturbance and immunity measuring apparatus - Antennas and test sites for radiated disturbance measurements (ISO 20318-1:2019, IDT) JIS S 6005 Leads for mechanical pencils 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 20318-1 and the following apply. ISO and lEC maintain terminological databases for use in standardization at the following addresses ——ISO Online browsing platform: available at https://www.iso.org/obp ——IEC Electropedia: available at http://www.electropedia.org/ 3.1 black lead solid writing material for mechanical pencil, which consists of black colour materials (e.g. graphite) anda binding agent, generating lines which are erasable 3.2 hardness degree combination of two alphanumeric or alphabetical symbols used to indicated the hardness and density(darkness) of the lead when used in writing Note 1: See Table 1. Note 2: Hardness increases from 6B to 9H, density ofline increases from 9H to 6B. Note 3: HB represents the median hardness degree. Note 4: A scientific definition of hardness degree is not yet available. 3.3 marking diameter numerical symbol used to classify leads by thickness (diameter) of lead Note: These are used to label or mark lead boxes to indicate a corresponding mechanical pencilspecified in ISO 20318-1. 4 Classification Black leads for mechanical pencils for general use shall be classified according to the hardness degreeand the marking diameter as specified in Table 1.