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The daily tools we use require various small parts for fastening. These are essential for the composition of our various machines. Today we will mainly introduce nuts and bolts.

Screws and Nuts

Nuts and bolts with the same specification can be connected together through the internal threads. For example, nuts of M4-P0.7 can only be connected with bolts of the M4-P0.7 series (in nuts, M4 means that the inner diameter of the nut is about 4mm , 0.7 refers to the distance between two thread teeth is 0.7mm). A nut is screwed together with a threaded bolt to play a role of fastening, and it is a part of hardware accessories that must be used in all manufacturing machinery. According to the material, it can be divided into carbon steel, stainless steel, non-ferrous metals (such as copper) and other major types.

It is a cylindrical threaded fastener matching nut. It needs to cooperate with a nut to fasten two parts with passing holes. This type of connection is called a bolted connection. If the nut is unscrewed from the bolt, the two parts can be separated again, so the bolt connection is a detachable connection.

Ordinary bolts can be divided into three levels of A, B, and C according to the manufacturing accuracy, A and B are refined bolts, and C are rough bolts. As for the connection bolts for steel structures, unless otherwise specified, they are usually ordinary coarse C-grade bolts. There are differences in the processing methods of different grades, and the corresponding processing methods are generally as follows: ① The bolts of A and B bolts are processed by a lathe, with a smooth surface and accurate dimensions. The material performance grade is 8.8, the production and installation are complex, and the price is relatively high. It is rarely used. ② C-level bolts are made of unprocessed round steel, the size is not accurate enough, and its material performance grade is 4.6 or 4.8. The deformation is large when the shear connection is connected, but the installation is convenient and the production cost is low. It is mostly used for tensile connection or temporary fixing during installation.

Installation process

1) Before installation
Before trying to pass a bolt through any hole, remove anything that may be present in the hole and make sure the bolt and hole are clean. Check again if you have a bolt that fits this type of hole. Because such holes may have threads for specific types of bolts, make sure the threads on the bolts also match.

After removing all impurities, screw the bolts into the holes. If it gets stuck or doesn't continue into the hole after a few twists, it is likely that you are using the wrong bolt. Do not try to insert or push it further, because it will damage the threads on the holes and bolts.

2) Use bolts
If the bolt is not stuck when screwed into the hole, and if it is long enough to protrude a little on the other side of the hole, it should work. The extra part on the other side of the bolt will be used to tighten the nut to fix the bolt and then hold the two objects together.

Insert the head of the bolt into the hole outward. For some bolts or holes, it is best to use a wrench to screw them.

3) Fix the bolt with a nut
Take a nut that fits the bolt and place it on the other side of the bolt, away from the head. Then grab the head of the bolt so that it does not move, and hold it in place while turning the nut clockwise, and press down gently. Continue to rotate and apply pressure until the nut rests against the bolt coming out of the hole and fixes the two objects together.

If it is difficult to hold the bolt when tightening the nut, consider fixing the head of the bolt with a wrench.