How to Prevent
Thread Galling
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:
Dicronite® Coating
- excess friction is present
- two contact materials have similar hardness
- the surface finish is rough or uneven
- lubrication is insufficient
- tightening speed and torque are too high
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.
Other Info
How to prevent thread galling:
| Factor | Description |
|---|---|
| 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.
- The coating works to prevent galling on all types of threads.
- Dicronite® can be applied to all metals. It is a great solution for preventing galling in troublesome materials such as stainless steel, aluminum, and titanium.
- The parts can be masked so only the area the customer specifies receives the coating.
- This thin lubricating film is ideal for systems requiring tight tolerances with its half micron thickness.
- The coating won’t attract dirt or debris like typical anti-seize compounds.
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.
Dicronite® is applied at one of many worldwide licensed coating facilities.
After surface preparation, Dicronite® is impinged onto the surface at high velocity.
The material includes no binders or adhesives and requires no curing.
All you have to do is:
- Tell us about your application
- Send components to one of our application facilities
- Receive your expertly coated parts with little lead time.
Dicronite® has various application facilities that can provide the following quality certifications:
NADCAP
ITAR
ISO9001
AS9100
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I was unaware of how many factors there were that affected a fastener’s ability to function properly. I’ll be sure to relay your article to my mother. She’s interested in getting some threaded fasteners for furniture assembly, but is unsure of what steps to take to obtain what she needs.
I found this content very well-written & easily understandable. I would like to appreciate your efforts. Thanks for sharing!
Thank you for giving it a read! Please let us know if you have any interest in getting some fasteners coated – submit RFQ. Thank you for your feedback!