Standards are norms, and each country and department has its own standards. At present, the most commonly used standards in our business are the following:
GB-Chinese 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 many standards in China, and 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). 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, and the like, the above-mentioned criteria are the difference in the thread portion. GB, DIN, JIS and other threads are all in MM (mm) units, collectively referred to as metric thread. Another thread like ANSI, ASME, etc. is called American Standard thread in inches. In addition to the metric thread and the American thread, there is also a BSW-inch standard, the thread is also in inches, commonly known as Wyeth's thread.
The metric thread is in MM (mm) and its cusp angle is 60 degrees. Both American and British threads are in inches. The cusp angle of the U.S. thread is also 60 degrees, while the cusp angle of the Imperial thread is 55 degrees. Due to the different units of measurement, the representation of various threads is not the same. For example, the M16-2X60 represents a metric thread. His specific meaning is to indicate that the nominal diameter of the screw is 16mm, the pitch is 2mm, and the length is 60mm. Another example: 1/4-20X3/4 means the inch thread, and his specific meaning is the nominal diameter of the screw. 1/4 inch (one inch = 25.4 MM), 20 teeth on one inch and 3/4 inch length. In addition, to express American screws, UNC and UNF are usually added after the English screws, to distinguish between coarse American teeth and fine American teeth.
In the domestic sales business, the most commonly encountered standards are GB (GB) and DIN (Germany).
In terms of non-aromatic products, the following standards will be mainly touched: GB30; GB5783; GB5782; GB52; GB6170; GB818; GB819; GB845; GB846; GB70; DIN912; DIN933; At present, GB30 (old national standard) has been replaced by GB5783 (new national standard) in the standard book.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.
In 1986, our country set a new standard for standard parts. It is commonly called the new standard in the business. The most commonly used standards are GB5780, GB5781, GB5782, GB5783, and GB5784. GB5780 is a hex-headed coarse-shaft half-screw screw whose accuracy grade is Class C. GB5782 can be used instead (GB5782 is a hexagonal head coarse-screw full-teeth screw whose accuracy is grade A and B.) GB5781 is a hexagon head Screws, grade C accuracy. GB5783 can be used instead (GB5783 is a hexagonal head full-teeth screw, its accuracy rating is A and B). GB5784 is a semi-hexagonal screw with a thin rod.
The difference between the new standard and the old one is that the products of the M8, M10, M12, M14, and M22 series are different in the width of the opposite side. In addition to the new products of the M22 series, the head-to-edge of the new standard products M8, M10, M12, and M14 is 1 mm smaller than the opposite side of the old standard. 13, 16, 18, 21 MM, respectively, and the M22 series of new products, the new standard than the old standard on the opposite side to 2MM, should pay special attention. For head thickness, there is a slight difference between the new standard and the old standard, which can be used if the requirements are not very strict.
The difference between the new standard and the German standard is: The product specifications of M10, M12, M14, and M22 are different in the width of the opposite side. The head-to-edge mark of M10, M12, and M14 is 1 mm smaller than the German mark. For the M22's new products, the head-to-edge width is 2mm larger than that of the German standard. Others can be used universally.
For hex nuts, the commonly used standards are: GB52, GB6170, GB6172 and DIN934. The main differences between them are: GB6170 thickness is thicker than GB52, GB6172 and DIN934, commonly known as thick nuts. The other is the edge of the difference, M8's nut series DIN934, GB6170, GB6172 on the opposite side is 13MM than the GB52 on the opposite side 14MM to be smaller 1MM, M10 nut, DIN934 and GB52 on the opposite side of 17MM, than GB6170 and GB6172 on the opposite side of the larger 1MM, M12 nut, DIN934, GB52 on the opposite side of the 19MM than the GB6170 and GB6172 on the opposite side 18MM to 1MM. For the M14 nuts, the opposite side of DIN934 and GB52 is 22MM larger than that of GB6170 and GB6172. The other is the M22 nut, DIN934, GB52 on the opposite side of the 32MM, than the GB6170, GB6172 on the opposite side of the 34MM to 2MM. (Except for the thickness of GB6170 and GB6172, the width of the opposite side is exactly the same.) The remaining specifications can be used without considering the thickness.