Introduction to the basic knowledge of stainless steel aviation parts processing and aerospace components

We know that a large number of components are needed in aerospace equipment, among which fasteners are indispensable. Without fasteners, the thousands of components of an aircraft would not be able to be combined together. Today, stainless steel aviation Parts Processing will briefly introduce the basic knowledge of fasteners to everyone.

I. Thread Type

There are many standards for threads, among which:

For coarse-threaded and fine-threaded threads of the same size and number, if the threads are the same, the nominal diameter of the thread is the same, but the number of threads per inch in length is different.

2. The distribution of tolerances varies. For threads with a diameter of 1 inch, the specific regulations are different. For instance, NF stipulates the use of 14 threads per inch and is generally represented by 1 to 14NF. UNF stipulates the use of 12 threads per inch and is represented by 1 to l2UNF.

Ii. Cooperation Level

Threads are classified into different grades. These different grades of threads indicate the degree of fit tightness that the threads should have.

Generally speaking, it has five grades. Grade 1 indicates a loose fit. When in use, the nut can be easily turned by hand. Grade 2 indicates free fit and is suitable for aviation screws. Grade 3 indicates a moderate fit, and most aviation bolts need to reach this grade. Grades 4 and 5 are tight fits and require the use of specialized tools. The higher the grade, the tighter the fit of the threaded pair.

Iii. Identification Symbols

The parameters such as the diameter, length and material of the bolts of the generally marked fasteners are as follows: the measurement unit for the diameter is 1/16in, and the measurement unit for the length of the bolt rod of the body is 1/8 in. The manufacturing materials of bolts are generally marked with English letters or symbols, where "C" indicates that the material used is stainless steel. "DD" indicates that the material used is 2024 aluminum alloy; "-" indicates that the material used is nickel alloy steel.

Iii. Nuts

There are also many types of nuts used in aerospace. The following introduces several commonly used nuts:

1. Standard aviation nuts

For instance, the AN310 channel top nut is generally used in conjunction with the AN3 to AN2O body bolts. Its thread standard is NF(fine thread), and materials such as nickel alloy steel, stainless steel, and 2024 aluminum alloy can all be used to produce this type of nut.

2. Self-locking nut

The common models of low-temperature self-locking nuts include AN365, AN364, etc. When locking, insert an elastic ring into the thread, and the inner diameter ratio should be slightly smaller than that of the thread. Rotate the nut to let the bolt pass through the bottom section of the thread and enter the top section of the thread. At this moment, the resistance of the elastic ring should be overcome so that the thread of the bolt and the nut can mesh in coordination. When using this type of fastener on an aircraft, there are requirements and restrictive conditions, and it should be used in accordance with the requirements.

Iv. Gasket

The main functions of washers in aerospace fasteners are: to make the force under the nut or bolt head more uniform, adjust the distance between the thread and the component surface, and at the same time, they can also serve to lock, prevent loosening and indicate preload, etc. The more commonly used high gaskets include AN960 ordinary gasket, AN935 open type elastic gasket, AN936B type external tooth type elastic gasket, etc.

The basic knowledge of aerospace components has been introduced here for now. I hope that after reading this, everyone can have a general understanding of aerospace fasteners.