An example of galling is the wear and tear caused by friction between two metal surfaces when they come into sliding contact. Fasteners made of stainless steel, steel, aluminium, or brass often experience thread galling. As a result, proper measures must be implemented from the outset in order to reduce the occurrence and risk of thread galling.
Galling’s impact on the design of threaded parts
The following are some of the detrimental effects of galling on mechanical parts’ design and manufacture:
Poor operating environment: The threaded fasteners are a key source of worry because of the potential for tiny particles and debris to enter the threaded fasteners. They might have an impact on mechanical parts' performance.
Failure probability: Galling causes the threads to become strained, stressed, and torn. Structural deformation of threaded parts may result from this.
Costly repairs: Fasteners, nuts, and screws may need to be repaired if they have been damaged in any way. Repairing internal thread galling is more difficult than fixing external thread galling because of the design of the mechanical parts.
How to prevent thread galling
Thread galling is prevented by a variety of practical approaches. Here are a few guidelines:
Reduction of wrench speed: Fasteners that are exposed to high temperatures are more susceptible to galling. As the speed of the wrench increases during the installation of fasteners, more heat is created. In order to reduce heat build-up in the wrenches, slow down their rotational speed.
Tighten tolerance: Galling may be avoided by using fasteners with a high tolerance in the threaded part. Because of this, fasteners are less prone to friction and sliding. As a result of thread rolling, the dimensions and tolerances of threaded fasteners like nuts and bolts will always be the same.
Lubricating the threads: To prevent friction and galling in threaded fasteners, special anti-galling lubricants may be used.
Utilise coarse threads: Galling may be minimised by using coarse threads rather than fine ones in the handling process. Coarse threads may take greater abuse during the handling process. Fasteners and nuts are also protected against galling because of a wider thread allowance (the distance between the actual and basic thread profile).
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