STAINLESS STEEL SERRATED FLANGED NUTS

Serrated Flanged Nuts — A serrated flange nut combines two functions in one part: an integral flange that replaces a separate flat washer, spreading clamp load over a wider bearing area than a standard hex nut's flat face, and a ring of serrations machined into the underside of that flange that bite into the mating surface as the nut is tightened. That bite is what gives this nut a genuine, if modest, self-locking action beyond plain friction — the teeth resist rotation mechanically, which is why serrated flange nuts are a common specification in automotive and machinery assemblies subject to vibration where fitting a separate lock washer or nylon insert nut would add an extra part and assembly step. The obvious consequence of that bite is that it marks the surface it's tightened against; where the mating face is painted, coated, plated, or otherwise needs to stay cosmetically intact, the non-serrated version (DIN 6923) is the better choice, since it spreads load the same way without gripping the surface. Serrated flange nuts are not a substitute for a genuine prevailing-torque lock like a nyloc or all-metal locking nut in high-vibration or safety-critical joints — the serration's grip is real but more modest than a dedicated locking mechanism, so where vibration is severe, pairing with (or upgrading to) a nylon insert flange nut such as DIN 6926 gives a more robust result. A2 stainless is the standard specification for general automotive and engineering use; A4 is worth the extra cost for anything outdoor, washed down, or exposed to road salt, since the flange's larger surface area means more metal exposed to whatever the environment throws at it. Sizing follows the mating bolt exactly as with any hex nut, with the flange diameter generally scaling with nominal thread size rather than being independently selectable.

FAQs
Does a serrated flange nut fully replace the need for a locking nut in a high-vibration joint?
Not entirely — the serration gives a genuine but modest degree of anti-rotation grip, which is enough for many general applications, but for severe or continuous vibration a nylon insert flange nut (DIN 6926) or a dedicated locking nut gives a more robust result.

Can a serrated flange nut be reused after removal?
Yes, unlike a nylon insert nut there's no polymer to degrade, though the serrations will show some wear each time they're tightened against a new bite point, so a visibly flattened or worn flange is worth replacing rather than reusing indefinitely.

Does the flange size vary independently of the thread size?
No, flange diameter is generally proportioned to the nominal thread size rather than offered as a separate option, so specifying the thread size determines the flange dimensions automatically.

How does this compare to a non-serrated flange nut?
A non-serrated flange nut (DIN 6923) spreads load over a larger bearing area without gripping the surface, whereas the serrated version adds mechanical resistance to rotation at the cost of marking the mating surface.