Measures to avoid screw locking

Editor:Jiaxing UNITEK Machinery Technology Co., Ltd. │ Release Time:2021-11-10 

Preventive measures and methods to avoid screw locking:

1. Choose the right product: Before use, confirm whether the mechanical properties of the product meet the requirements of use, such as the tensile strength of the screw and the guaranteed load of the nut. Choose the appropriate screw length, which is subject to 1-2 pitches of the exposed nut after tightening.

2. Before use, check whether the thread is rough, whether there is iron filings or dirt between the threads, these things often cause lockup.

3. Lubrication spa for fasteners before use: It is recommended to use butter, molybdenum disulfide, mica, graphite or talc for lubrication. At present, wax dipping is commonly used for lubrication and anti-locking.

4. Pay attention to the method of use

  A. The speed and force of screwing in should be appropriate, not too fast or too big. Use torque wrenches or socket wrenches as much as possible, and avoid using adjustable wrenches or electric wrenches. Too fast will cause the temperature to rise rapidly and cause lock-up.

  B. In the direction of force, the nut must be screwed in perpendicular to the axis of the screw.

5. The use of washers can effectively prevent the problem of over-locking.

6. Locking or seizure often occurs on fasteners made of stainless steel, aluminum alloy and titanium alloy materials. These metal alloys themselves have anti-corrosion properties and will produce a thin oxide layer on the metal surface when the surface is damaged. To prevent further corrosion. When the stainless steel fasteners are locked, the pressure and heat generated between the teeth will destroy the oxide layer, causing blockage or shearing between the metal threads, and then adhesion. When this phenomenon continues to occur, the stainless steel fasteners will be completely locked and can no longer be removed or continued to be locked. Usually this series of blocking, shearing, adhering, and locking actions take place in just a few seconds, so a correct understanding of the use of these types of fasteners can prevent this phenomenon.

Some friends may also wonder why stainless steel fasteners sometimes have locking problems, but carbon steel fasteners do not often have similar phenomena? This depends on the two materials of stainless steel and iron. The stainless steel standard parts are softer and have better ductility. The hardness of stainless steel standard parts is SUS316. Compared with the hardness of iron standard parts, it is softer than that of iron standard parts 8.8. Stainless steel has good ductility, but its hardness is somewhat different from that of carbon steel.

Seeing this, I think everyone should have a better understanding of the reasons for the locking of stainless steel fasteners, remember the method, and prevent the locking phenomenon from happening!