I believe everyone knows that self-tapping screws do not need nuts, because it is born with cool and anti-loose skills. But have you heard that stainless steel screws can't be used with nuts?
This is why?
The reason for this is that, when the low temperature pipe flange is assembled, if it is fastened with stainless steel bolts and nuts, it is very easy to bite after a while. This condition occurs because after the screw is tightened, the overall structure of the thread and the bolt may be slightly deformed, resulting in a tighter snap; or after a long time, the screw and the screw hole may be "fused".
At this point, it is particularly difficult to remove the bolts and nuts, which will require more force to overcome the friction of the threaded joints and overcome the energy generated by the deformation of the material and the destruction of the intermolecular polymerization.
In order to avoid difficult to disassemble, you can take the following methods:
1. The material of the nut is replaced by a copper nut to avoid fusion.
2. Apply grease to the screw before screwing the nut;
3. Anti-bite agent is used to prevent corrosion, sintering, rust and abrasion of parts under high temperature conditions.
In addition to stainless steel bolts can not be used with nuts, the problem of locking stainless steel fasteners in daily life, what is going on?
Stainless steel fasteners are often used for fastening on more expensive machine parts due to their aesthetics, durability and corrosion resistance.
However, metal fasteners often rust due to various reasons, and the fasteners may be completely locked when rusted, resulting in the failure of the fastener itself to operate, that is, the fastener cannot be removed or continued to be locked. Complete locking of the fastener may only occur within a few seconds.
Here to give you some little knowledge of science, the probability of locking down to low in use:
1. Select the product: Before use, confirm whether the mechanical properties of the product can meet the requirements of use, such as the tensile strength of the screw and the guaranteed load of the nut. The length of the screw should be properly selected to tighten the nut and expose the nut 1-2 tooth pitch;
2. Whether the thread is rough and there is iron filings or dirt between the threads, which will result in locking;
3. Lubrication of fasteners: Lubricating with butter, molybdenum disulfide, mica, graphite or talc. At present, it is generally treated with dipping wax to prevent lubrication and lock;
4. The gasket can effectively prevent the problem of over-tightening;
5. Locking or seizure often occurs on fasteners made of stainless steel, aluminum alloy and titanium alloy. These metal alloys have anti-corrosion properties and will produce a thin oxide layer on the metal surface when the surface is damaged. To prevent further rust.