Locks often occur when stainless steel fasteners are used, but if carbon steel fasteners are used, this is rarely the case. What is the reason? In fact, the reason for its own is that the stainless steel material is relatively soft relative to carbon steel. Because of the good ductility of stainless steel materials, there is a gap between the physical hardness and carbon steel to a certain extent.
But this is only one aspect, and there is a reason for the material itself. As stainless steel has rust proof properties, when the surface is damaged, it is easy to form a layer of thin oxide layer on the surface to prevent further corrosion. When the stainless steel fastener is locked, the thermal pressure formed between the thread and the oxide layer will destroy the middle ground, resulting in stainless steel thread blocking and direct shear, and the adhesion. When the sticky situation persists, the stainless steel fastener will be completely locked so that it can not be unloaded or locked. Generally this series of movements is formed in only a few seconds. So first of all, we need to know the characteristics of stainless steel and follow the correct operation procedures to prevent the locking of stainless fasteners.
In addition, there are 5 main external reasons leading to the lock of stainless steel fasteners. First of all, the product is not selected correctly. Before application, it is necessary to confirm whether the mechanical properties of the product can meet the requirements. In addition, the length of the screw should be suitable, and the best standard is to show the pitch of one to two teeth after the screw is tightened.
The second point is the rough teeth or foreign objects. If there are solder joints or other metal clips sandwiched between the teeth, it will often cause the lock of stainless steel fasteners.
The third point is too much force or too fast locking speed. When using, it is best to operate manually, instead of using electric wrench. Because of the fast locking speed of electric wrench, the rapid rise of temperature is very easy to cause death.
Fourth is the direction of the force direction error, it is necessary to notice that the nut must be perpendicular to the axis of the screw to do the rotation, and the incline operation is prohibited.
The last point is that the flat, elastic washer is not used, because this can effectively prevent the lock from tightening.
So what are the precautions to prevent the locking of stainless steel fasteners? First of all, when using stainless steel fasteners, it is best to lock the nut at a fixed speed. Usually slow down the lock speed can effectively reduce the probability of lock death. This is because the thermal energy is produced when the lock is locked, and the increase of heat energy will increase the probability of lock death.
Secondly, it is best to lubricate screws or nuts before locking. The lubricating oil can be lubricated with butter, molybdenum disulfide, graphite, mica or talcum powder to lubricate the internal and external dental veins, so as to reduce the locking probability.
The third way is to use different grades of screws and nuts, such as 304 and 316. However, it is necessary to pay attention to whether the stainless steel grade is selected to meet the requirements of its corrosion resistance.
Source: China Stainless Steel Fasteners Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)