Complete set of basic knowledge of bolts and nuts

The parameters that need to be indicated for fasteners include: product name (standard), specifications, material, strength grade, and surface treatment. For example: DIN912、M4-0.7x8、SCM435、 12.9 level, blackened.
1. Product Name (Standard)
Note: For screws without standards, which are non-standard parts, drawings are required.
For example, DIN912, Chinese name: Hexagon socket head screw, this is the product name.
However, the most accurate approach is to refer to the standard, as GB70 also has the same product name; But there are many places where the dimensions of the two standards are not consistent.
The most influential standards in the world are: German Standards (DIN), International Standards (ISO), Chinese National Standards (GB), American Standards (ANSI), and Japanese Standards (JIS).
2. Specifications
Generally, screws are referred to as the diameter of the tooth pattern multiplied by the length of the screw.
The commonly used metric diameters for tooth patterns include M2, M3, M4, M5, M6, M8, M10, M12, etc;
The commonly used ones in the American system include: 4 # -40, 6 # -32, 8 # -32, 10 # -24, 1/4-20, 5/16-18, 3/8-16, 1/2-13, etc.
The length of the screw refers to the effective length of the embedded object. For example, countersunk screws are loaded with the total length, semi countersunk screws need to add the length of half the head, while cylindrical screws do not include the head size in their length. For example:
For specifications, it is best to include the tooth spacing in the full name. For example, M4-0.7x8, the outer diameter of 4 teeth is 4mm, 0.7 refers to the distance between two tooth peaks of 0.7mm, and 8 refers to the effective length of 8mm embedded in the loaded object.
For the sake of simplicity, we do not write the tooth spacing, and assume that coarse teeth are standard teeth because they are the most common; So there's no need to label it. This is only available in the metric system, but American products still need to be marked with tooth spacing.
Here we will focus on the specifications of American screws, such as 6 # -32 * 3/8. 6 # is the outer diameter of the tooth, which is close to 3.5mm; 32 is 32 teeth per inch of thread length (equivalent to the pitch of a metric screw); 3/8 is the length of the screw (same as metric screws).
Here are two formulas to remember: tooth outer diameter A #=(Ax0.013+0.06) x25.4 (mm), 1 inch=25.4mm.