How many types of bolts are there on a car?

Bolts are the most used parts in cars, and many auto mechanics jokingly call themselves "screw-screwers". If you look closely at the bolts, you will see that the bolts come in a variety of different shapes and have different numbers on the bolts. What does all this mean? Today we will talk about the knowledge of automotive bolts.
According to the detour direction of the thread: it is divided into two types: left-handed thread and right-handed thread. The vast majority of threads are right-handed threads, and a very small number of special parts use left-handed threads according to the number of threads can be divided into single-wire threads, double-wire threads and three-wire threads, of which single wires are mostly used for connection, and others are mostly used for transmission.
According to the shape of the thread, it is divided into triangle thread, rectangular thread, trapezoidal thread and zigzag thread. Among them, the triangular thread has good self-locking and high strength of the threaded teeth, which is generally used for joining and is the most widely used thread. According to the pitch is divided into two categories: coarse teeth and fine teeth, coarse tooth thread is the basic thread, fine tooth thread screw strength is high, but the strength of threaded teeth is lower than coarse tooth thread, generally used in thin-walled pipe fittings, shaft parts and precision mechanism adjustment parts. When the screw diameter is greater than 70mm, only fine tooth threads can be used.

How many types of bolts are there in a car?

Usually the bolt strength in the "hardware standard parts" is divided into 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9 and other more than 10 grades, these numbers are bolt performance grade numbers. Among them, the bolts of grade 8.8 and above are made of low carbon alloy steel or medium carbon steel and heat treated, collectively referred to as high-strength bolts, and the rest are collectively referred to as ordinary bolts. The bolt performance grade number is composed of two parts of numbers, which indicate the nominal tensile strength value and yield ratio value of the bolt material, which are generally expressed by "X.Y", such as 4.8, 8.8, 10.9, 12.9 and so on. X*100=tensile strength of this bolt, X*100*(Y/10) = yield strength of this bolt.
For example:
Performance class 4.8 bolts, the meaning of which is:
  1. The nominal tensile strength of bolt material reaches 400MPa;
  2. The yield ratio of bolt material is 0.8;
  3. The nominal yield strength of bolt material reaches 400×0.8=320MPa
Performance level 8.8 high-strength bolts, after heat treatment, can achieve:
  1. The nominal tensile strength of bolt material reaches 800MPa;
  2. The yield ratio of bolt material is 0.8;
  3. The nominal yield strength of bolt material reaches 800×0.8=640MPa
Performance class 10.9 high-strength bolts, the material of which can be heat treated to:
  1. The nominal tensile strength of bolt material reaches 1000MPa;
  2. The yield ratio of bolt material is 0.9;
  3. The nominal yield strength of bolt material reaches 1000×0.9=900MPa grade
The meaning of bolt performance level is an international standard, bolts of the same performance level, regardless of the difference in their materials and origin, their performance is the same.