GB/T 71-2018 in English

《GB/T 71-2018开槽锥端紧定螺钉》由TC85（全国紧固件标准化技术委员会）归口，主管部门为中国机械工业联合会。

ChinaStandards.net is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.

This standard is one of the national standard series of Slotted Set Screws which consist of:
— GB/T 71 Slotted Set Screw with Cone Point;

— GB/T 73 Slotted Set Screw with Flat Point;

— GB/T 74 Slotted Set Screw with Cup Point;

— GB/T 75 Slotted Set Screw with Long Dog Point;

— GB/T 77 Hexagon Socket Set Screws with Flat Point;

— GB/T 78 Hexagon Socket Set Screws with Cone Point;

— GB/T 79 Hexagon Socket Set Screws with Dog Point;

— GB/T 80 Hexagon Socket Set Screws with Cup Point;

— GB/T 83 Square Set Screws with Long Dog Point and Rounded End;

— GB/T 84 Square Set Screws with Cup Point;

— GB/T 85 Square Set Screws with Long Dog Point;

— GB/T 86 Square Set Screws with Short Dog Point and Cone End;

— GB/T 821 Square Set Screws with Chamfered End.

This standard is drafted in accordance with the rules given in GB/T 1.1-2009.

This standard replaces GB/T 71-1985 Slotted Set Screws with Cone Point in whole, and the following technical deviations have been made with respect to the GB/T 71-1985:

— thread standards quoted are unified as GB/T 193 and GB/T 9145 (see Clause 2 and Table 2);

— the specifications of thread M3.5 are added (see Table 1);

— general technical conditions are specified in 16938 is added (see Table 2);

— the mechanical properties of stainless steel are modified to A1-12H, A2-12H and A4-12H (see Table 2; Table 2 of Edition 1985);

— non-ferrous metals CU2 and CU3 are added (see Table 2);

— the surface oxidation treatment of steel screws is deleted, and the untreated and non-electrolytically applied zinc flake coating are specified in GB/T 5267.2 is added (see Table 2; Table 2 of Edition 1985);

— the surface oxidation treatment of stainless steel screws is deleted, and the specifications of simple treatment and passivation of stainless steel screws are specified in GB/T 5267.4 is added (see Table 2; Table 2 of Edition 1985);

— "d<1.6mm, as agreement” is added for property class of steel and stainless steel screws (see Table 2);

— “If other specifications or surface treatment are needed, they shall be negotiated between supplier and customer” is added (see Table 2);

— the requirements for surface defects of steel screws is added (see Table 2).

This standard has been redrafted and modified adoption of International Standard ISO 7434:1983 Slotted Set Screws with Cone Point.

The main technical deviations between this standard and the International Standard ISO 7434:1983, together with their justifications, are as follows:

— the provision of ISO 7434:1983: "If other specifications are required, selected …… from ISO 3506 and ISO 4759-1" is deleted (see Clause 1 of ISO 7434:1983), which does not fall within the scope of this standard;

In normative references, Chinese standards are used in place of international standards (see Clause 2); references to GB/T 90.2 (see Table 2), 3098.16 (see Table 2), GB/T 5267.2 (see Table 2), GB/T 5267.4 (see Table 2), GB/T 5779.1 (see Table 2), GB/T 16938 (see Table 2) and GB/T 1237 (see 5.1) are added; and references to ISO 888 and ISO 4753 are deleted to cater basic standards of fasteners in China;

— general technical conditions are specified in 16938 is added (see Table 2), so as to meet the development requirements of slotted set screw standard;

— non-ferrous metals CU2 and CU3 are added (see Table 2), so as to extend the scope of application;
— the property class of stainless steel is modified to A1-12H (see Table 2) so as to meet the new material of slotted set screws;

— "d<1.6mm, as agreement” is added for property class of steel and stainless steel screws (see Table 2), in order to clarify the provisions of the property grade of small specifications of products;

— the surface oxidation treatment of steel screws is deleted, and the untreated and non-electrolytically applied zinc flake coating are specified in GB/T 5267.2 is added (see Table 2) ), in order to meet the anti-corrosion requirements of steel screw surface;

— the surface oxidation treatment of stainless steel screws is deleted, and the specifications of simple treatment and passivation of stainless steel screws are specified in GB/T 5267.4 is added (see Table 2), in order to meet the anti-corrosion requirements of the surface of stainless steel screws;

— in order to improve the quality of products, the requirements for surface defects of steel screws are added according to the basic standards of fasteners;

— technical specifications for packaging (see Table 2) are added to satisfy basic standard of fasteners in China;

— designation example is modified to a simplified one in 5.2 to meet the requirements of GB/T 1237.

This standard was proposed by China Machinery Industry Federation.

This Standard is under the jurisdiction of National Technical Committee 85 on Fasteners of Standardization Administration of China (SAC/TC 85).

The explanations of this standard is in the charge of the Secretariat of SAC/TC 85.

The previous editions of this standard are as follows:

— GB 71-1958, GB 71-1966, GB 71-1976, GB/T 71-1985.


Slotted Set Screws with Cone Point

1 Scope

This standard specifies types, dimensions, technical specifications and designation of slotted set screws with cone point.

This standard is applicable to the slotted set screws with flat point and thread sizes from M1.2 to M12 inclusive and product grade A.

2 Normative References

The following referenced documents are indispensable for the application 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.

GB/T 90.1 Fasteners — Acceptance Inspection (GB/T 90.1-2002, ISO 3269:2000, IDT)
GB/T 90.2 Fasteners — Marking and Packaging
GB/T 193 General Purpose Metric Screw Threads — General Plan (GB/T 193-2003, ISO 261:1998, MOD)
GB/T 1237 Designation System for Fasteners (GB/T 1237-2000, eqv ISO 8991:1986)
GB/T 3098.3 Mechanical Properties of Fasteners — Set screws (GB/T 3098.3.3-2016, ISO 898-5:2012, MOD)
GB/T 3098.16 Mechanical Properties of Fasteners — Stainless Steel Set Screws (GB/T 3098.16-2014, ISO 3506-3: 2009, MOD)
GB/T 3103.1 Tolerances for Fasteners — Bolts, Screws, Studs and Nuts (GB/T 3103.1-2002, idt ISO 4759-1:2000)
GB/T 5267.1 Fasteners — Electroplated Coatings (GB/T 5267.1-2002, ISO 4042:1999, IDT)
GB/T 5267.2 Fasteners — Non-electrolytically Applied Zinc Flake Coatings (GB/T 5267.2-2002, ISO 10683: 2000, IDT)
GB/T 5267.4 Passivation of Corrosion-resistant Stainless-steel Fasteners (GB/T 5267.4-2009, ISO 16048:2003, IDT)
GB/T 5276 Fasteners — Bolts, Screws, Studs and Nuts — Symbols and Descriptions of Dimensions (GB/T 5276-2015, ISO 225:2010, MOD)
GB/T 5779.1 Fasteners — Surface Discontinuities — Bolts, Screws and Studs for General Requirements (GB/T 5779.1-2000, idt ISO 6157-1:1988)
GB/T 9145 General Purpose Metric Screw Threads — Limits of Sizes for the Screw Threads of Medium Quality and Preferable Plan (GB/T 9145-2003, ISO 965-2:1998, MOD)
GB/T 16938 Fasteners — General Requirements for Bolts, Screws, Studs and Nuts (GB/T 16938-2008, ISO 8992:2005, IDT)
3 Type and Dimension

For types and dimensions of screws, see Figure 1 and Table 1.

Symbols and descriptions of dimensions shall meet GB/T 5276.


a The 120° angle is mandatory for short length screws above the dotted stepped line in Table 1.
b The 90° angle applies only to the portion of the point below the root diameter of the thread with nominal lengths I below the dotted stepped line in Table 1. For short length screws above the dotted stepped line a 120° angle is mandatory. The angle 90° or 120° applies only to the portion of the point situated below the root diameter of the thread.
c Incomplete thread u ≤ 2P.

Figure 1

 
Table 1 Dimension Dimensions in millimetres


Note: The range of preferred lengths is between the dotted stepped line:
a Sizes in brackets should be avoided if possible.
b P is the pitch of the thread
c ≤M5 no flat part on the cone required; the point may be slightly rounded.

4 Specifications and Reference Standards

See Table 2 for the specifications and reference standards.

Foreword II
1 Scope
2 Normative References
3 Type and Dimension
4 Specifications and Reference Standards
5 Designation