GB/T 821-2018 in English

Interpretation of the National Standard of the People's Republic of China GB/T 821—2018

Standard Overview and Revision Background

GB/T 821—2018 "Square Head Flat Point Set Screws" is one of the important standards in the field of machinery industry, which mainly regulates the type, size, technical conditions and marking method of square head flat point set screws. This standard replaces the old version of the standard in 1988. The main revisions include:

• Add general technical conditions GB/T16938
• Optimize the mechanical property grade of stainless steel
• Introduce non-ferrous metal material specifications
• Improve surface treatment technical requirements

Standard Framework Comparison Table

Technical conditions and practical applications

Mechanical properties:The mechanical property grade of square head flat point set screws is divided into A grade, which is suitable for fixing and connecting a variety of mechanical equipment. Its hardness grades include 33H, 45H, etc., to ensure reliability under different working conditions.

Dimensional parameters:The thread specification range is from M5 to M20, and the nominal length can be selected according to the specific application requirements. The size code and marking should comply with the GB/T5276 standard.

Implementation suggestions and precautions

1. Strictly select the material grade and surface treatment method according to the standard.
2. Pay attention to the tolerance matching of the screws during assembly to ensure a stable connection.
3. For special requirements, it is recommended to negotiate with the supplier to clarify the technical details.