What are the Reasons for the Rotating and Non-Rotating Loosening of Fasteners?

 As a Railway Fastening System Exporter, let me share with you. The use of threaded fasteners is very extensive, and the problem that gives us a headache is the loosening of threaded fasteners during use. In response to this problem, inventors have been designing methods to prevent loosening of fasteners, and there are many mechanisms that cause fasteners to loosen. Recently, the standard parts network has learned that the rotating and non-rotating loosening mechanisms of fasteners are as follows: It is the prerequisite knowledge we share with you, and I hope it will be helpful to everyone.

Railway Fastening System

Railway Fastening System

Rotating and non-rotating loosening

In most applications, threaded fasteners are to be tightened in order to apply pre-tightening force in the joint. Loosening can be defined as the loss of pre-tightening force after tightening is completed. This can happen in either of two ways. Rotation loosening, usually called self loosening, refers to the relative rotation of fasteners under external load. Non-rotational loosening means that there is no relative rotation between the internal thread and the external thread, but preload loss will occur.

Fastener loosening caused by non-rotating loosening

After assembly, deformation of the fastener itself or the joint may cause non-rotational looseness. This may be the result of partial plastic collapse of these interfaces. When the two surfaces are in contact with each other, the asperities on each surface bear the pressure load of the supporting surface. Since the actual contact area of the bump may be much smaller than the macro area, even under moderate load, the stress of the protrusion due to the surface roughness will be greater than the yield strength of the material, and these protrusions will bear very high local stress, resulting in Plastic deformation.

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