STAINLESS STEEL COMBY-NUTS WITH CONICAL WASHER

​​​​​​​Comby-Nuts with Conical Washer — A comby-nut is a hexagon nut with a conical spring washer fitted captively underneath it before it ever leaves the factory, so the two components are handled, fed, and fitted as a single part rather than assembled by hand from separate pieces. The washer remains free-spinning while captive, and its conical, dished profile compresses slightly as the nut is tightened, applying continuous spring force to the joint rather than the flat, rigid bearing surface of a standard nut or plain washer. That spring action is the whole point: it helps the joint maintain clamp tension as the assembly settles, as surfaces bed in, or as temperature cycling causes minor expansion and contraction — situations where a rigid joint can quietly lose preload over time even though the nut itself never physically backs off. Typical applications include machinery subject to vibration or thermal cycling, panel fixings on equipment with dissimilar material expansion rates, and any assembly where maintaining consistent clamp load matters more than achieving the absolute maximum static torque. It's a genuinely different mechanism from a KEP nut, which uses a flatter washer (often serrated) to bite into the mating surface and resist rotation directly, rather than a conical washer's spring compensation — so the choice between the two depends on whether the joint's main risk is rotational loosening (favouring a KEP nut) or preload loss from settling and thermal movement (favouring a comby-nut). A2 stainless suits general indoor machinery use; A4 is worth the extra cost outdoors or in washdown environments, since both the nut and washer are exposed to whatever the surrounding conditions are. Sizing follows the mating bolt's diameter and pitch as with any nut, with the captive washer diameter fixed to the nut size rather than independently selectable.

FAQs
Does the conical washer eventually lose its spring effect?
Over a very long service life or repeated heavy compression cycles the washer can take a permanent set and lose some of its spring action, similar to any disc spring, though for most general applications it performs reliably across the working life of the joint.

Can a comby-nut be used in place of a standard nut plus a separate spring washer?
Yes, that's essentially its purpose — combining the two into one captive part removes the risk of the washer being omitted or fitted the wrong way round during assembly, while giving the same spring-compensation benefit.

How does this differ from a KEP nut?
A comby-nut uses a conical, spring-action washer to maintain clamp force under vibration or thermal movement, whereas a KEP nut typically uses a flatter, often serrated washer that bites into the mating surface primarily to resist rotation rather than provide spring compensation.

Does the captive washer reduce assembly time?
Yes, because the nut and washer are supplied as one component, there is no risk of a loose washer being misplaced or omitted during assembly, and fitting is faster than handling two separate parts.