What Is Thread-Locking Fluid?


Thread-locking fluid by Monroe Fasteners are commonly used in the construction of airplanes. It’s estimated that a typical 747 airliner has over 3 million fasteners.

While some of these fasteners consist of rivets, others consist of bolts or screws with external threading. Threaded fasteners such as these are often installed thread-locking fluid. What is thread-locking fluid exactly, and why is it used in the aerospace manufacturing industry?

Overview of Thread-Locking Fluid

Also known as thread-locker, thread-locking fluid is a liquid adhesive product that’s designed to “lock” threaded fasteners in place. It’s been around for over a half-century. The world’s first thread-locking fluid was invented in 1953 by American engineer and professor Vernon Krieble. Krieble discovered that threaded fasteners would often loosen when exposed to vibrations, so he developed thread-locking fluid as a solution.

Threaded fasteners, of course, are characterized by the use of threading. They are used in conjunction with other threaded fasteners to join or secure parts together. Rather than inserting a threaded bolt directly into a threaded hole, however, you may want to coat it with thread-locking fluid beforehand. After drying, the thread-locking fluid will solidify while securing the bolt in the hole.

Benefits of Using Thread-Locking Fluid

With thread-locking fluid, you don’t have to worry about threaded fasteners loosening due to vibrations. It will secure the threaded fasteners with which it’s used in place.

Thread-locking fluid is commonly used in the aerospace manufacturing industry for this reason. Airplanes produce vibrations during flight. When exposed to these vibrations, threaded fasteners may loosen. Exposure to vibrations over a prolonged period can cause threaded fasteners to separate from the holes and nuts with which they are used. Fortunately, thread-locking fluid offers a solution.

There are different types of thread-locking fluid. Most thread-locking fluid can be categorized as either permanent, low strength or removable. Permanent thread-locking fluid is designed to create a permanent hold.  Low-strength thread-locking fluid, on the other hand, is designed to weaker hold. Finally, there’s removable thread-locking fluid, which as the name suggests, is designed to create a strong but nonpermanent hold.

Thread-locking fluid is easy to use. It comes in small bottles similar to craft or wood glue. You can open the cap to reveal the nozzle, followed by squeezing a small amount of thread-locking fluid out the bottle and onto the fastener’s threading. After allowing the thread-locking fluid to dry, the fastener should be secure. As long as the thread-locking fluid coats the threading, it will lock the fastener in place.

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