Standard specifications for screws?

Standards are norms, and each country and department has its own standards. GB—Chinese 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
GB—National Standard is one of many standards in our country. In addition, there are industry standards, professional standards and departmental standards. National standards are divided into GB (mandatory standards), GB/T (recommended standards) and GBn (national internal standards). What we usually see like GB30, GB5783, etc. are mandatory standards.
In addition to the differences in basic dimensions such as the opposite side of the head and the thickness of the head in the above several standards, the most important thing is the difference in the threaded part. The threads of GB, DIN, JIS, etc. are all based on MM (millimeters), collectively referred to as metric threads. In addition, threads such as ANSI and ASME are called American standard threads in inches. In addition to the metric thread and the American thread, there is also a BSW-imperial standard, the thread is also in inches, commonly known as Wyeth thread.
In the usual domestic sales business, the most frequently encountered standards are GB (National Standard) and DIN (German Standard).
In terms of production products, the following standards are mainly encountered: GB30; GB5783; GB5782; GB52; GB6170; GB818; GB819; GB845; GB846; GB70; DIN912; DIN933; DIN931, etc. GB30 (old national standard) has been replaced by GB5783 (new national standard) in the standard book. GB52 (old national standard) has been replaced by GB6170 (new national standard) in the standard book.

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