What is thread galling?
Thread galling refers to a phenomenon that occurs when threaded fasteners, such as bolts, screws, or nuts, seize or lock up during installation or removal. It is also known as thread seizing, cold welding, or friction welding.
Thread galling typically happens when:
Implications of thread galling:
Thread galling can have several implications and negative effects, which can impact the performance, reliability, and safety of threaded fasteners and the overall systems they are part of. Some of the implications of thread galling include:
Galling can cause damage to the threaded surfaces, resulting in wear, deformation, or even the stripping of threads. This compromises the integrity and functionality of the fastener.
As galling progresses, the threads become more seized and locked together, requiring higher levels of torque to tighten or loosen the fastener. This can make disassembly or adjustment difficult or even impossible without risking further damage.
Galled threads may compromise the structural integrity of joints or connections. Weakened fasteners can lead to loosening, inadequate clamping force, or the potential for catastrophic failure in critical applications.
Thread galling can affect the smooth operation of mechanisms or equipment that rely on threaded fasteners. Stuck or damaged fasteners can impede proper assembly, disassembly, or adjustment, resulting in operational inefficiencies or downtime.
In applications where threaded connections require sealing, such as fluid or gas systems, thread galling can lead to leaks or inadequate sealing. This can result in fluid loss, compromised performance, or contamination.
Addressing thread galling often requires additional maintenance or repair efforts. This can involve disassembling and replacing of galled components, which can be time-consuming and costly, especially in complex or inaccessible systems.
Thread galling can pose safety risks, especially in industries where reliable fastening is critical. Equipment failures or structural integrity compromises due to galled threads can lead to accidents, injuries, or even loss of life.
How to prevent thread galling:
|Lubrication||Apply an appropriate lubricant to the threaded surfaces before assembly. Lubricants reduce friction and act as a barrier between the mating threads, minimizing the chances of galling. Use lubricants specifically designed for threaded fasteners, such as anti-seize compounds or assembly greases.|
|Material Selection||Choose compatible materials for threaded components. Avoid combinations of materials with similar hardness, as they are more prone to galling.|
|Surface Finish||Maintain smooth and uniform surface finishes on threaded components. Properly machined and finished surfaces reduce the likelihood of galling by minimizing friction and providing a more even contact area.|
|Torque Control||Follow recommended torque specifications during assembly. Avoid excessive tightening torque, as it can increase the risk of galling. Use calibrated torque wrenches or other appropriate tools to ensure proper and consistent tightening without exceeding the recommended limits.|
|Avoid Rapid Assembly||Avoid high-speed assembly or disassembly of threaded fasteners. Rapid rotation can generate excessive heat due to increased friction, which can contribute to galling. Take your time and apply steady, controlled force during the tightening or loosening process.|
|Pre-Assembly Inspection||Inspect threaded components before assembly. Check for any visible signs of damage, burrs, or irregularities that could increase the risk of galling. Ensure that threads are clean and free from debris or contaminants that may affect their performance.|
How Dicronite® can help:
Dicronite® is a dry film lubricant (tungsten disulfide) that has been used as an anti-galling coating in various industries and high precision applications.
Thread galling coating for 65+ years.
Dicronite® is a dry film lubrication made up of tungsten disulfide.
It can be applied to all metals, most plastics and some ceramics; may be applied on other coatings and platings as well.
COATING THICKNESS – 0.5 micron (0.00002 inch) or less
THERMAL STABILITY – up to 538°C in air; 1316°C in vacuum
COMPATIBILITY – compatible with greases, oils, fuels, fluids, and many solvents.
Join countless engineers who use Dicronite® to prevent galling.
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