GB/T 9996.2-2026Inspection of the appearance quality of cotton, man-made fibre and blended yarns wound on a blackboard — Part 2: Individual assessment (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents".

This document is Part 2 of GB/T 9996, "Blackboard Inspection Method for Appearance Quality of Pure and Blended Cotton and Chemical Fiber Yarns". The following sections have been released.

---Part 1: Comprehensive Assessment Method;

---Part 2: Separate Assessment Method. This document replaces GB/T 9996.2-2008.

Compared with GB/T 9996.2-2008, apart from structural adjustments and editorial changes, the main technical changes are as follows.

---Added terms and definitions for large neps, visible coloured neps and impurities (see 3.6, 3.7, 3.8);

---The principles have been changed (see Chapter 4, Chapter 3 of the 2008 edition);

---The requirements for the evenness inspection room, the nep and impurity inspection room, the blackboard and the blackboard winding machine have been revised (see 5.1, 5.2, 5.3 and 5.4; 4.1, 4.2, 4.3 and 4.4 of the 2008 edition);

---Added content on the stand and the black cover plate used for nep and impurity inspection (see 5.5, 5.6);

---The inspection steps have been expanded to include the yarn arrangement density and the width of the yarn sheet (see 8.1);

---The requirements for inspectors have been revised (see 9.1; 8.2 and 8.3 of the 2008 edition), and a downgrading requirement for visible coloured neps has been added (see 9.2.5);

---Rules for expressing the test results (see 9.2.9) and for inspecting visible coloured neps on the blackboard (see 9.4) have been added;

---The contents of the test report have been changed (see Chapter 10, Chapter 9 of the 2008 edition).

Introduction

The blackboard inspection method for yarn appearance quality is one of the core inspection standards in the cotton textile industry, and it stands out for its ease of operation, intuitiveness, and high efficiency.

Appearance quality assessment has long been a reliable method for evaluating yarn appearance quality, and is widely used in the production control and quality management of pure cotton and chemical fiber yarns, as well as blended yarns.

The method is used throughout quality inspection and trade. It is a key basis for production acceptance, trade transactions and arbitration inspection, and it lays a theoretical foundation for applying AI-based inspection technology to yarn quality testing. To meet the inspection needs of different scenarios, GB/T 9996, "Inspection Method for Appearance Quality of Pure and Blended Cotton and Chemical Fiber Yarns (Blackboard Method)," divides the inspection methods into comprehensive evaluation method and separate evaluation method.

The two parts provide comprehensive support for the standardization of industry inspections.

---Part 1: Comprehensive Evaluation Method. The purpose is to comprehensively assess the evenness of yarn sample and the presence of neps and other impurities.

It can simply and intuitively reflect the overall appearance quality level of the yarn, and is suitable for scenarios where the overall quality of the yarn needs to be quickly controlled.

---Part 2: Separate Evaluation Method. The purpose is to classify and refine key quality indicators such as yarn evenness and cotton knots/impurities.

It addresses the inspection needs of multi-variety, small-batch production and gives an efficient and precise quality judgement for such scenarios.

1 Scope

This document describes a method for comparing the yarn evenness shown on the blackboard with a standard sample and for counting the neps, impurities and visible coloured neps on the blackboard.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.

For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies to this document.

GB/T 8170 Rules for rounding off numerical values and the representation and determination of limiting values

3 Terms and Definitions

The following terms and definitions apply to this document.