When installing flat washers with nuts, you will more or less encounter the problem of front and back installation: the smooth side and the rough side (opposite), which side should be closer to the part is better, and what is the big difference?
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Solve one of the problems first, and use the front and back of the flat pad.
We know that flat pads are mainly stamped out of iron plates. The shape is generally a flat washer with a hole in the middle. With spring pads, they are installed in the order of one spring pad and one flat pad, that is, the flat pad is next to the surface of the machine, and the spring pad is on the between the flat washer and the nut.
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There are two functions, one is to increase the contact area between the screw and the machine; the other is to eliminate the damage to the surface of the machine when the spring pad removes the screw.
It can be seen from this that how to use the front and back mainly depends on what function the flat pad needs to achieve.
If it is only used to reduce looseness, then you can choose to put the non-smooth surface close to the part. But if you want to better protect the part, it is better to choose a smooth surface close to the surface of the part.
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You may want to ask again, if both are implemented, or which method of use is the least risky to choose?
This involves the second question: What is the big difference between the front and back?
The calculation formula in the "Quality Encyclopedia of Standard Fasteners" published by China Standard Publishing House is: thousand piece weight m=0.00785×{3.1416/4×washer height×[square of outer circle diameter-square of inner hole diameter]}. However, due to the different standards of various countries and the inaccuracy of information, here is a standard for American flat pads for everyone.
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That is to say, when making production flat pads, a surface treatment that is as smooth as possible on both sides is achievable.
In this way, when we customize or purchase flat pads from the factory, we can make requests. For example, if the smooth surface is required to be close to the surface of the part in industrial production, but at the same time it is required to reduce the wear of the part, the required standard can be carried out, and of course the purchase price needs to be increased accordingly.
In fact, in general, the probability of looseness is far less than that of the part surface that is often damaged due to the connection.
It's like most people tell you, that with the rough side facing away from the nut and the smooth side close to the part surface, this solution works.
In addition to the above metal flat gaskets, non-metallic flexible gaskets in processing and production are also very common. For example, rubber gasket, graphite gasket, asbestos gasket, asbestos-free gasket, silicone gasket and so on.
The sealing accuracy of these gaskets also needs to be paid attention to. The premise of these realizations is the precision of cutting gaskets.
Take the flange gasket as an example.
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The flange seal mainly relies on the pretightening force of the connecting bolts to achieve sufficient sealing specific pressure through the gasket to prevent the leakage of the sealed pressure fluid medium. There are many reasons for its leakage. The compression force of the sealing gasket is insufficient, the roughness of the joint surface does not meet the requirements, the deformation of the gasket and mechanical vibration will cause the joint surface of the sealing gasket and the flange to leak. .
