How Many Kinds Of Bolts Are There On A Car?

Bolts are the most used parts in cars, so many auto mechanics call themselves “screwers.” If you look closely at the bolts, you will see that the bolts come in different shapes and there are different numbers on the bolts. So what does all of this mean? As a professional fastener manufacturer, Xinchi Fastener Company is pleased to introduce that to you. Today we talk about car bolts.

According to the direction of thread winding, auto bolts can be divided into left – and right-handed screw threads. The thread of most automobile bolts is a right-handed thread, only a few special parts use left-handed thread bolts.

According to the number of threads, automotive bolts can be divided into a single thread, double thread, and three threads, of which a single thread is used for connection, and the other is used for transmission.

According to the shape of the thread, automotive bolts can be divided into triangular thread, rectangular thread, trapezoidal thread, and sawtooth thread. The triangle thread has good self-locking and high thread strength. It is generally used for connection and is the most widely used thread.

According to the pitch, automotive bolts can be divided into coarse teeth and fine teeth. Coarse thread is the basic thread, and fine thread screw strength is high, but its threaded tooth strength is lower than coarse thread, generally used for thin-wall pipe fittings, shaft parts, and precision mechanism adjustment parts.

Usually, the bolt strength of “hardware standard parts” is divided into more than 10 grades, such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, and so on. These numbers are the performance-grade labels of bolts. The 8.8 bolts and above are made of low-carbon alloy steel or medium carbon steel and have been heat-treated. They are collectively referred to as high-strength bolts, and the rest are referred to as ordinary bolts. The performance grade label of a bolt is composed of two parts, which respectively represent the nominal tensile strength value and the bending strength ratio of the bolt material. Generally, it is expressed by “X.Y”, such as 4.8, 8.8, 10.9, 12.9, etc. X*100= tensile strength of this bolt, X*100*(Y/10)= yield strength of this bolt.

For example:

A bolt of Class 4.8 performance is defined as:

1. The nominal tensile strength of bolt material reaches 400MPa;
2. The bending ratio of bolt material is 0.8;
3. The nominal yield strength of bolt material is up to 400×0.8=320MPa.

After heat treatment, the material of 8.8 high strength bolt of performance class can reach:

1. The nominal tensile strength of bolt material reaches 800MPa;
2. The bending ratio of bolt material is 0.8;
3. The nominal yield strength of bolt material up to 800×0.8=640MPa class.

After heat treatment, the material of 10.9 high strength bolt of performance class can reach:

1. The nominal tensile strength of bolt material reaches 1000MPa;
2. The bending ratio of bolt material is 0.9;
3. The nominal yield strength of bolt material up to 1000×0.9=900MPa class

The meaning of bolt performance grade is the international general standard. Bolts with the same performance grade have the same performance regardless of the difference in material and origin.

Anji Xinchi Fastening Piece Co., Ltd is a trustworthy fastener company, especially in furniture nuts. And we are the designated fastener supplier to“STAPLE”. As a trusted fastener supplier,  Xinchi Fastener Company can offer a wide range of high-quality fasteners, including tee nuts, screws, bolts, rivets, washers, etc. If you want to know more about fasteners or want to wholesale fasteners, please feel free to contact us. And then our experienced and expert service team will reply to you as soon as possible.