Fastener is a kind of mechanical part which is widely used for fastening connection. It is widely used in various machinery, equipment, vehicles, ships, railways, bridges, buildings, structures, tools, instruments, chemicals, instruments and supplies. It is the most widely used mechanical foundation.
It is characterized by a wide variety of specifications, different performance uses, and standardization, seriation, generalization of the degree is also very high. Therefore, some people also call a kind of fastener with existing national standards as standard fastener, or referred to as standard fastener for short.
The parameters to be indicated for the description of fasteners are: product name (standard), specification, material, strength grade and surface treatment. For example: DIN912, m4-0.7×8, SCM435, grade 12.9, blackened.
1. Product name (standard)
Note: for non-standard screws, drawings are required.
For example, DIN912, Chinese Name: Hexagon socket head cap screw, this is the product name.
However, the most accurate way is to call the standard, because gb70 is also the same product name; however, there are many differences between the two standards.
The most influential standards in the world are DIN, ISO, GB, ANSI and JIS.
2. Specifications
Generally speaking, the screw is called thread diameter * screw length.
The tooth pattern is called diameter. The metric system commonly used are: m2, m3, M4, M5, M6, M8, M10, M12, etc;
The common American systems are: 4 × 40, 6 × 32, 8 × 32, 10 × 24, 1 / 4-20, 5 / 16-18, 3 / 8-16, 1 / 2-13, etc.
The screw length refers to the effective length of the embedded object. For example: the countersunk head screw is loaded with the total length, and the length of the half countersunk head screw should be added with the length of the half head, while the length of the cylindrical head screw does not include the size of the head.
Such as:
For specifications, it is best to add pitch. For example, m4-0.7×8, the outer diameter of four fingers is 4mm, 0.7 refers to the distance between two thread peaks is 0.7mm, and the effective length of eight fingers embedded in the object is 8mm.
In order to simplify and not write the pitch, we default coarse thread to standard thread, because they are the most common, so there is no need to mark them. This metric system only has, the American system product still must mark the thread distance.
