Introduction to some standards and specifications and description of requirements

Standards are norms, and each country and department has its own standards. At present, the most commonly used standards in our usual business are as follows:

GB-Chinese National Standard (GB) ANSI-American National Standard (US Standard)

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

BSW-British National Standard JIS-Japanese National Standard

GB-national standard is one of the many standards in China, as well as 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 like GB30,GB5783 and so on are mandatory standards.

The above standards in addition to some basic dimensions such as the head side, head thickness, etc., the most important is the difference of the threaded part. GB, DIN, JIS and other threads are MM (mm) as the unit, collectively referred to as metric thread. Another thread like ANSI, ASME, etc. is in inches called American standard thread. In addition to metric threads and American threads, there is also a BSW-inch standard. Its threads are also measured in inches, commonly known as Wyeth threads.

Metric thread is MM (mm) as the unit, its cusp angle is 60 degrees. Both US and English threads are in inches. The cusp angle of US thread is also 60 degrees, while that of English thread is 55 degrees. Due to the different units of measurement, the representation of various threads is also different. For example, something like M16-2X60 represents a metric thread. His specific meaning is that the nominal diameter of the screw is 16MM, the pitch is 2MM, and the length is 60MM. Another example is: 1/4-20X3/4 refers to imperial threads. His specific meaning is that the nominal diameter of the screw is 1/4 inch (one inch = 25.4MM), there are 20 teeth on one inch, and the length is 3/4 inch. In addition, if you want to express American screws, you will usually add UNC and UNF after the English screws to distinguish between American coarse teeth and American fine teeth.

In the usual domestic sales business, the standards we most often encounter are GB (national standard) and DIN (German standard).

In terms of non-aromatic products, the following standards are mainly exposed: GB30;GB5783;GB5782;GB52;GB6170; GB818;GB819;GB845;GB846;GB70;DIN912;DIN933;DIN931, etc. 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 formulated a new standard for standard parts, which is commonly known as the new standard in business. The most used ones are GB5780, GB5781, GB5782, GB5783 and GB5784. GB5780 is a hexagon head thick rod half tooth screw, its accuracy grade is C.

Grade A products can be replaced by GB5782 (GB5782 is a hexagonal head thick rod full-tooth screw, and its accuracy is Grade A and Grade B.) GB5781 is a hexagonal head full tooth screw with a precision grade of C. GB5783 can be used instead (GB5783 is a hexagonal head full tooth screw, and its accuracy grade is A and B). GB5784 is a hex screw with thin rod half teeth.

The difference between the new standard and the old standard is that the products of M8, M10, M12, M14 and M22 series are different in the width of the opposite side. In addition to the M22 series of new products, the opposite sides of the heads of the new standard products M8, M10, M12 and M14 are 1MM smaller than the opposite sides of the old standard products. They are 13, 16, 18 and 21MM respectively, while for the new products of M22 series, the new standard is 2MM larger than the opposite side of the old standard, which should be paid special attention. For the head thickness, there is a slight difference between the new standard and the old standard, which can be used in general if the requirements are not very strict.

The difference between the new standard and the German standard is that the product specifications of M10, M12, M14 and M22 are different in the width of the opposite side. The new marks on the opposite sides of the heads of M10, M12 and M14 are 1MM smaller than those of German marks. However, the width of the opposite side of the head of the M22 new product is 2MM larger than that of the German standard, and the others can be used universally.

For hexagonal nuts, commonly used standards are: GB52, GB6170, GB6172 and DIN934, for the main difference between them are: GB6170 thickness than GB52, GB6172 and DIN934 to thick, commonly known as thick nut. The other is the difference between the opposite sides. In M8 nut series, the opposite sides of DIN934, GB6170 and GB6172 are 13MM smaller than the opposite side 14MM of GB52. In M10 nut, the opposite side of DIN934 and GB52 is 17MM, which is 1MM larger than the opposite side of GB6170 and GB6172. In M12 nut, the opposite side of DIN934 and GB52 is 1MM larger than GB6170. For M14 nut, the opposite side of DIN934 and GB52 is 22MM larger than the opposite side of 21MM of GB6170 and GB6172. In addition, the nut of M22, the opposite side of DIN934 and GB52 is 32MM, which is 2MM smaller than the opposite side 34MM of GB6170 and GB6172. (GB6170 and GB6172 in addition to its thickness is not the same, the width of the opposite side is exactly the same) other specifications without considering the thickness of the case, can be universal.

In terms of hexagon socket, there are two versions in the national standard, one is GB70-76, the 76-year version and the other is GB70-85 85-year version. Our company now implements DIN912 standard, so we should pay attention to the difference in actual business operation: GB70-85 completely coincides with DIN912, so there is no difference in the use of the new standard, mainly the difference between GB70-76 and DIN912: M8 series hexagon socket products, the round head diameter of GB70-76 is 12.5MM, which is smaller than 13.27MM of DIN912. For M10 series hexagon socket products, the round head diameter of GB70-76 is 15MM, which is smaller than 16.27 of DIN912. For M12 series hexagon socket, the round head diameter of GB70-76 is 18MM, which is smaller than 18.27 of opposite sides of DIN912. For M16 and M20 series hexagon socket GB70-76, the round head diameter of 0MM is smaller than DIN33912, respectively 24MM,30MM. DIN912 is 24.33MM and 30.33MM respectively. In addition, the width of the inner opposite side between the old standard and the German standard hexagon is different due to different standards, and the inner opposite side of the GB70-76 is smaller, which should also be paid attention to in business operations.

In addition, there are some differences in carriage screws that may be used at ordinary times. Here is also an explanation. In the national standard, there are two standards for carriage screws, namely GB12 (small semicircular head square neck screw) and GB14 (large semicircular head square neck screw). At ordinary times, the German standard DIN603 is more commonly used in the market. Now to distinguish these three: for the round head and neck, in the same specification comparison is: GB12