Hexagon nut standard.
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 (JPY) BSW - British National Standard
GB - National standard is one of the many standards in China. In addition, there are industry standards, professional standards and departmental standards, etc. National standards are further classified into: GB (Mandatory Standards), GB/T (Recommended standards), and GBn (National Internal Standards), etc. The standards we usually see, such as GB30 and GB5783, are all mandatory standards.
The above-mentioned standards, apart from some basic dimensions such as the edge of the head and the thickness of the head, mainly differ in the threaded parts. Threads of GB, DIN, JIS and other standards are all measured in MM (millimeters) and are collectively referred to as metric threads. In addition, threads like ANSI and ASME are measured in inches and are called American standard threads. In addition to metric threads and American threads, there is also a BSW - imperial standard, whose threads are also measured in inches and are commonly known as Wyeth threads.
Metric threads are measured in MM (millimeters), and their tip Angle is 60 degrees. Both American threads and British threads are measured in inches. The tip Angle of American-made threads is also 60 degrees, while that of British-made threads is 55 degrees. Due to the differences in measurement units, the representation methods of various threads are also not the same. For example, "M16-2X60" represents metric threads. Its specific meaning is that the nominal diameter of the screw is 16MM, the pitch is 2MM, and the length is 60MM. For example, 1/4-20x3/4 represents the imperial standard thread. Its specific meaning is that the nominal diameter of the screw is 1/4 inch (one inch =25.4MM), there are 20 threads on one inch, and the length is 3/4 inch. In addition, when indicating American screws, "UNC" and "UNF" are usually added after indicating British screws to distinguish whether they are American coarse threads or American fine threads.
In terms of raw products, the following standards will mainly be encountered: GB30; GB5783; GB5782; GB52; GB6170; GB818; GB819; GB845; GB846; GB70; DIN912; DIN933; DIN931, etc. At present, GB30 (the old national standard) has been replaced by GB5783 (the new national standard) in the standard book. GB52 (the old national standard) has been replaced by GB6170 (the new national standard) in the standard book.
In 1986, our country formulated new standards for standard parts, which are generally referred to as new standards in business. The most commonly used ones mainly include GB5780, GB5781, GB5782, GB5783, and GB5784. GB5780 is A hexagonal head thick bar half-thread screw with a precision grade of C. It can be replaced by GB5782. (GB5782 is a hexagonal head thick bar full thread screw with a precision grade of A and B.) GB5781 is a hexagonal head full thread screw with a precision grade of C product. GB5783 can be used as A substitute (GB5783 is a hexagonal head full thread screw with precision grades A and B). GB5784 is a hexagonal screw with a thin bar and half thread.
The difference between the new standard and the old one lies in that the products of the M8, M10, M12, M14 and M22 series have differences in the width of the opposite sides. Except for the new products of the M22 series, the head sides of the new standard products M8, M10, M12 and M14 are 1MM smaller than those of the old standard ones. They are 13, 16, 18 and 21MM respectively. However, for the new products of the M22 series, the opposite side of the new label is 2MM larger than that of the old label. Special attention should be paid to this. There is a slight difference in the thickness of the head between the new standard and the old one. They can be used interchangeably when the requirements are not very strict.
