What are the classifications of screws?

Screw standard specification
Standards are standards, and each country and part has its own standards. Now, the most commonly used standards in our usual business are as follows:
GB-my country 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. Others include professional standards, professional standards and some standards. National standards are divided into GB (mandatory standards), GB/T (recommended standards) and GBn (national internal standards). We often see GB30, GB5783 and so on are mandatory standards.
In addition to the differences in base standards such as the opposite side of the head and the thickness of the head, 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 whose thread is also in inches, commonly known as Wyeth thread.
Metric thread is based on MM (millimeter), and its cusp angle is 60 degrees. Both American and British threads are measured in inches. The cusp angle of the American thread is also 60 degrees, while the cusp angle of the British thread is 55 degrees. Because of the different measurement units, the marking methods of various threads are different. For example, M16-2X60 indicates a metric thread. His detailed 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 indicates an inch thread, and his detailed meaning is the nominal diameter of the screw It is 1/4 inch (one inch = 25.4MM), there are 20 teeth on one inch, and the length is 3/4 inch. For other American screws, UNC and UNF are usually added to the back of the imperial screws to distinguish between American coarse or fine teeth.
In the usual domestic sales business, the most frequently encountered standards are GB (National Standard) and DIN (German Standard).
In terms of non-Fragrant products, the following standards will be first encountered: GB30; GB5783; GB5782; GB52; GB6170; GB818; GB819; GB845; GB846; GB70; DIN912; DIN933; DIN931, etc. Now 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 drafted a new standard for standard parts, which is generally called the new standard in business. The most commonly used ones are GB5780, GB5781, GB5782, GB5783, and GB5784. GB5780 is a hexagonal head thick shank half-thread screw, and its accuracy grade is C grade product, which can be replaced by GB5782 (GB5782 is a hex head thick shank full-thread screw, and its accuracy is grade A and B.) GB5781 is a hexagon head full-thread screw Thread screw, accuracy grade is C grade product. It can be replaced by GB5783 (GB5783 is a hexagon head full-thread screw, and its accuracy grades are A and B). GB5784 is a hexagonal screw with a thin rod and half tooth.
The difference between the new standard and the old standard is: M8, M10, M12, M14, and M22 series products have differences in the opposite side width. Except for the new products of the M22 series, 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. Respectively 13, 16, 18, 21MM, and the new products of the M22 series, the new standard is 2MM larger than the opposite side of the old standard, so special attention should be paid. Regarding the thickness of the head, there is a slight difference between the new standard and the old standard, which can be used in general when the requirements are not very severe.
The difference between the new standard and the German standard is that the product standards of M10, M12, M14, and M22 differ in the width of the opposite sides. The new heads of M10, M12, and M14 are 1MM smaller than the German standard. For the new product of M22, the opposite side of the head is 2mm larger than the opposite side of the German standard. Others can be used in general.
Regarding hexagonal nuts, commonly used standards are: GB52, GB6170, GB6172 and DIN934. The main differences between them are: GB6170 is thicker than GB52, GB6172 and DIN934, commonly known as thick nuts. The other is the difference between the opposite sides. In the M8 nut series, the opposite sides of DIN934, GB6170, and GB6172 are 13MM which is 1MM smaller than the 14MM of GB52. For the M10 nut, the opposite side of DIN934 and GB52 is 17MM, which is smaller than The opposite side of GB6170 and GB6172 is 1MM larger. For M12 nuts, the opposite side of DIN934 and GB52 is 19MM, which is 1MM larger than the opposite side of GB6170 and GB6172, 18MM. Regarding the M14 nut, the 22MM opposite to DIN934 and GB52 is 1MM larger than the 21MM opposite to GB6170 and GB6172. The other is the M22 nut. The opposite side of DIN934 and GB52 is 32MM, which is 2MM smaller than the 34MM opposite of GB6170 and GB6172. (GB6170 and GB6172 have the same width on opposite sides except for their different thicknesses.) The other standards can be used universally without considering the thickness.

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