GB - China National Standard (GB)
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 is one of the many standards in China. There are also industry standards, professional standards, and departmental standards. The national standards are divided into: GB (compulsory standards) and GB/T (recommended standards) and GBn (national Internal standards). The things we usually see like GB30, GB5783, etc. are all mandatory standards.
In addition to some basic dimensions such as head-to-edge, head thickness, etc., the most important are the differences in the thread portion. Threads in GB, DIN, JIS, etc. are all in MM (millimeter) units. Commonly referred to as metric thread. Another thread like ANSI, ASME, etc. is called the American standard thread in inches. In addition to the metric thread and the United States system thread there is a BSW-inch standard, the thread is also in inches, commonly known as Wyeth Thread.
The metric thread is in MM (mm) and it has a cusp angle of 60 degrees. American and British threads are all in inches. American threads also have a cusp angle of 60 degrees, and the British thread has a cusp angle. For 55 degrees. Due to the different units of measurement, resulting in a variety of thread representation is not the same. For example, the M16-2X60 is a metric thread. His specific meaning is that the screw's nominal diameter is 16MM, teeth Distance is 2MM, length is 60MM
Another example: 1/4-20X3/4 is the inch thread, the nominal diameter of the screw is 1/4 inch (one inch = 25.4mm), 20 teeth in one inch, length is 3/4 Inches. In addition to the American screws, the UNC and UNF are usually added after the English screws. The difference is the American coarse or fine American teeth.