Standard specification for self-tapping screws: The standard is the specification, and each country and department has its own standards for self-tapping screws. At present, the more popular self-tapping screw specifications are as follows:
GB—China National Standard (National Standard)
ANSI—American National Standard (American Standard)
DIN—German National Standard (German Standard)
ASME - American Society of Mechanical Engineers Standard
JIS—Japanese National Standard (Japanese Standard)
BSW - British National Standard
The GB-national standard of commonly used self-tapping screw specifications is one of many standards in my country. In addition, there are industry self-tapping screw specifications, professional self-tapping screw specifications and departmental self-tapping screw specifications. The national standard self-tapping screw specifications are divided into GB (mandatory standard), GB/T (recommended standard) and GBn (national internal standard). We usually see GB30, GB5783, etc. are mandatory standards.
In addition to the differences in the basic dimensions of the above self-tapping screw grid standards, such as head-to-side, head thickness, etc., the most important thing is the difference in the threaded part. The threads of GB, DIN, JIS, etc. are all in MM (millimeters), which are collectively referred to as self-tapping screw specifications metric threads. Another thread like ANSI, ASME, etc. is called American standard self-tapping screw specification thread in inches. In addition to metric threads and American threads, there is also a BSW-imperial standard, whose threads are also in inches, commonly known as Wyeth threads.