Essential: Screw standard knowledge

In 1986, our country set new standards for standard parts, which are commonly referred to as new standards in the business. The most used ones are GB5780, GB5781, GB5782, GB5783, and GB5784. GB5784 is a hexagonal screw with a thin rod and a half tooth. GB5781 is a hexagonal head full-screw screw with a precision class C. GB5780 is a hex head thick rod half-screw, its accuracy grade is C-class product, can be replaced by GB5782 (GB5782 is a hex head thick rod full-tooth screw, its accuracy is grade A and B. Can be replaced by GB5783 (GB5783 It is a hexagonal head full-screw with an accuracy class of A and B).

In the usual domestic sales business, the standards we most often encounter are GB (national standard) and DIN (German standard).
Standard screws are the norms, and each country and department has its own standards. At present, the most commonly used standards in our usual business are the following:
GB—The national standard is one of many standards in China. There are also industry standards, professional standards and departmental standards. . National standards are divided into: GB (mandatory standards) and GB/T (recommended standards) and GBn (national internal standards). We usually see GB30, GB5783 and so on are mandatory standards.

JIS - Japanese National Standard (Japanese Standard) BSW - British National Standard

DIN - German National Standard (German Standard) ASME - American Society of Mechanical Engineers Standard

GB - China National Standard (GB) ANSI - American National Standard (American Standard)

In terms of non-products, the following standards are mainly encountered: GB30; GB5783; GB5782; GB52; GB6170; GB818; GB819; GB845; GB846; GB70; DIN912; DIN933; DIN931. GB52 (old national standard) has been replaced by GB6170 (new national standard) in the standard book. At present, GB30 (old national standard) has been replaced by GB5783 (new national standard) in the standard book.

In addition to some basic dimensions such as head-to-edge, head thickness, etc., the most important ones are the difference in threaded parts. In addition to metric and American threads, there is also a BSW-inch standard, the thread is also in inches, commonly known as Wyeth thread. Threads of GB, DIN, JIS, etc. are all in units of MM (mm), collectively referred to as metric threads. Another thread like ANSI, ASME, etc. is called the American standard thread in inches.

Note: The metric thread is in MM (mm) and its cusp angle is 60 degrees. In addition, if you want to indicate the US-made screws, you will usually add UNC and UNF to the back of the inch screws to distinguish between American-made coarse teeth and American-made fine teeth. His specific meaning is that the nominal diameter of the screw is 16MM, the tooth pitch is 2MM, the length is 60MM, and another example is: 1/4-20X3/4 means the inch thread, his specific meaning is the nominal diameter of the screw. It is 1/4 inch (one inch = 25. For example, the M16-2X60 is a metric thread. Due to the different units of measurement, the representation of various threads is not the same. The cusp angle of the US thread is also 60. Degree, while the inch angle of the inch thread is 55 degrees. Both the US thread and the inch thread are in inches. 4MM), there are 20 teeth on one inch and 3/4 inches in length. (Source: Wanguan Hardware Machine Grid)



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