GB/T 28253-2025Thread forming tap (English PDF)

Foreword

This document was drafted in accordance with the rules provided in GB/T 1.1-2020 Directives for Standardization - Part 1: Rules for the Structure and Drafting of Standardizing Documents.

This document serves as a replacement for GB/T 28253-2012 Thread Forming Tap. In comparison with GB/T 28253-2012, apart from structural adjustments and editorial modifications, the main technical changes are as follows.

a) The scope of application is modified (see Chapter 1; Chapter 1 of Version 2012);

b) The dimensions of the tap thread part are added (see Tables 1 and 2);

c) The tap type diagrams are modified (see Figure 1 ~ Figure 3; Figure 1 ~ Figure 3 of Version 2012);

d) The types of the tap thread part are added (see 4.3);

e) The marking requirements for the thread forming tap are added (see 4.4), and the marking examples are modified (see 4.4; 3.7 of Version 2012);

f) The content related to non-ground taps is deleted (see 3.4, Table 8 ~ Table 10, and 5.5 of Version 2012);

g) The limit deviations of the dimensions of precision taps are added (see 5.2);

h) The technical requirements for taps are modified (see Table 9, Table 10, Table 14 and 6.11; Table 9, Table 10, Table 13 and 5.9 of Version 2012);

i) The content related to tap materials is deleted (see 5.8 of Version 2012);

j) A new chapter on “Inspection Methods” is added (see Chapter 7).

Please be noted that certain content of this document may involve patents. The institution issuing this document does not undertake the responsibility of identifying these patents.

This document was proposed by China Machinery Industry Federation.

This document shall be under the jurisdiction of National Technical Committee 91 on Cutting Tools for General Purpose of Standardization Administration of China (SAC/TC 91).

The drafting organizations of this document. Changzhou Hengding Tools Manufacturing Co., Ltd.; Shanghai Tool Works Co., Ltd.; Shanghai Cutting Tool Factory Co., Ltd.; Chengdu Xincheng Measurement Tools Co., Ltd.; Jiangsu Shidai Jiangyu Cutlery Co., Ltd.; Guangdong Dtech Technology Co., Ltd.; Chengdu Tool Research Institute Co., Ltd. Thread Forming Tap

1 Scope

This document specifies the types and dimensions, thread tolerances, technical requirements, inspection methods, marking and packaging of thread forming taps.

This document applies to thread forming taps used for machining regular threads (GB/T 192, GB/T 193, GB/T 196, GB/T 197) with nominal diameters of 1 mm to 27 mm on non-ferrous metals and low- to medium-strength ferrous metal parts.

NOTE 1.several explanations regarding tap thread tolerances are provided in Appendix A.

NOTE 2.dimensions of pre-drilled thread holes are provided in Appendix B.

NOTE 3.tap profiles and grinding allowances are provided in Appendix C.

NOTE 4.the relations of symbols between this document and ISO 13399 (all parts) are provided in Appendix D.

2 Normative References

GB/T 4267

3 Terms and Definitions

This document does not have terms or definitions that need to be defined.

4 Types and Dimensions