Galling is a type of wear that occurs when two metal surfaces meet, especially under stress. This is distinct from abrasive wear, where particles of material are torn away and moved off the surface. Rather, galling results in the transfer of microscopic grains from one surface to another that become stuck or diffusion welded to the other surface, creating a gouged appearance. The problem becomes much more severe when the contact pressure is high and the surface area of the contacting materials is small.
The most common cause of galling is a lack of adequate lubrication. This can be addressed by ensuring that the proper lubricant is used. MISUMI has a wide range of specialty and stainless steel fasteners that are more resistant to galling than typical hardware. This type of hardware also benefits from being lubricated prior to use.
However, even when the right lubrication is used, galling can still occur due to high temperatures and excessive friction between the metals involved. This friction creates heat, which can increase the metallurgical bond between the surfaces and increase adhesion. This can lead to a failure in the system that is usually very time-consuming and costly to repair.
A good way to prevent galling is to reduce the amount of force exerted during installation. This can be done by lowering the bolt load or using a special anti-seize solution that is matched to the environment of the application. Another method is to install the fastener slowly, allowing the heat generated by friction to dissipate before tightening further.
In addition, it is important to inspect the bolts for signs of damage that may increase the risk of galling. Dirty bolts with debris in the threads can greatly increase the chance of galling, as this will decrease the ability of the bolt to disperse the frictional heating generated by contact with the mating surface.
It is also important to select the right materials for applications that require frequent sliding of surfaces. Typically, metals that are similar or identical to each other will be more susceptible to galling than metals that are of different alloy grades.
The best way to avoid galling is to use a premium stainless steel that has been developed to minimize this issue. This can be accomplished by choosing stainless bolts that are made with a higher grade of steel, selecting nuts that are made of a more corrosion-resistant metal, and installing the fasteners at low speeds. By taking these steps, the likelihood of galling can be greatly reduced. Manufacturing industry executives should be aware of the serious implications of galling, and take measures to ensure that their equipment is protected against this dangerous problem. The safety and quality of expensive production machinery cannot be left to chance. For more information, please contact a BUMAX representative. galling