External causes of locking phenomenon in stainless steel standard parts
(1) If the product is not properly selected, it should be confirmed whether the mechanical properties of the product can meet the requirements of use (such as the tensile strength of the screw and the safety load of the nut). In addition, the length of the screw should be selected appropriately to tighten the nut to one to two pitches.
(2) Rough teeth or foreign matter sticking If there are solder joints and other metal chips mixed between the teeth, it often leads to locking.
(3) If the force is too strong or the locking speed is too fast, use a torque wrench or a socket wrench as much as possible to avoid using an adjustable wrench or an electric wrench. Because the electric wrench often causes the locking speed to be too fast, the temperature rises rapidly and locks up.
(4) The direction of the force direction is incorrect. The nut must be screwed perpendicular to the axis of the screw. Do not tilt.
(5) The use of the washer washer/retainer without the use of the washer can effectively prevent the problem of over-tightening.
Precautions and solutions to prevent the locking of stainless steel standard parts
1. When using stainless steel, do you always lock the nut at a fixed speed?
If you are a first-time user who is not familiar with the stainless steel process, you should consult your supplier about the characteristics of stainless steel. In general, slowing down the lock can greatly reduce (or even completely avoid) the chance of locking. Because thermal energy often occurs when it is locked, when the heat energy increases, the probability of locking increases. When in use, the speed of locking the stainless steel fasteners should be lower than the speed of locking the carbon steel.
2. Is the screw or nut lubricated before locking?
If the answer is “Noâ€, it is recommended to use butter, molybdenum disulfide, graphite, mica or talc to lubricate the inner and outer teeth to reduce the lock. Coating is also an effective way to lubricate. The nut that is buckled will have a more lubricating film between the nut and the screw.
3. Do you choose the same grade of screws and nuts?
If the answer is yes, it is recommended to use different grades of screws and nuts, such as 304 with 316 and so on. However, it should be noted that the grade of stainless steel selected must also meet its own rust and corrosion resistance requirements.
In addition, the most common case of locking when locking the flange. Suppose you have noticed and followed the above points, including the use of washers, using nuts (may also recommend the use of longer nuts, such as GB6170 or DIN934), diagonally on the nut, slowly screwing to the appropriate tightness Degree, etc., if it still can't be solved, it can't be unloaded after pre-locking. Finally, you have to temporarily use carbon steel nut when pre-locking the flange device, and then use the stainless steel screw when you finally lock it. Cap, find a balance between beautiful rust and no lock.
Stainless steel standard parts are prone to lock-up and lock-up, so we must first find out the cause of the lock-up phenomenon. Then, the targeted analysis and processing of the cause of the lock is carried out, and the solution is selected to solve the locking problem of the stainless steel standard parts at a reasonable and correct speed. 
Editor in charge: Hu Na
Guangzhou Jointair Co., Ltd. , https://www.nbjointair.com