ISO 20318-2:2019 一般的な使用のためのシャープペンシルとリード—分類、寸法、品質、およびテスト方法—パート2：黒いリード | ページ 2

Foreword

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The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives ).

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This document was prepared by Technical Committee ISO/TC 10, Technical product documentation.

A list of all parts in the ISO 20318 series can be found on the ISO website.

Introduction

This document was developed in response to the recent increase in popularity of mechanical pencils and their leads among students who use them for general writing, and where varieties of both hardness degrees and thickness (designated as marking diameter) of leads have been expanding in response to different types of usage. It should be noted that the entire production volume of mechanical pencils has been increasing every year, whereas the production of mechanical pencils for technical drawings has been decreasing.

Despite those recent trends, ISO 9177-1 was revised in 2011 with a scope limited to technical drawing usage only.

Therefore, it is clear that this document is necessary for general use and that it should be independent of technical drawings. The ISO 20318 series consists of two parts: mechanical pencils and black leads.

A set of a mechanical pencil and lead of the same marking diameter should be completely complementary, and should be compatible even with pencils and lead from different manufacturers.

It should also be noted that there are two issues which have not been resolved since the first relevant standard was published. First, on marking of labelling the diameters on mechanical pencils and cases of leads, two designations coexist: 0,35 and 0,3 and 1 and 0,9. This document attempts to clarify this designation issue by defining diameters precisely. Second, a scientific definition of hardness degree of leads is not yet available. Even though this document tried to establish a solely quantitative evaluation method, qualitative evaluation turned out to be inevitable. The issue, therefore, remains unresolved.

The title of the 2016 third edition of ISO 9177-1 was revised to distinguish it clearly from this document with the addition of “for technical drawings”.

1 Scope

This document specifies classification, dimensions, quality and test methods for black leads used for mechanical pencils for general writing, as specified in ISO 20318-1.

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.

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 IEC maintain terminological databases for use in standardization at the following addresses:

Bibliography