How Thick of Steel Can You Use a Rivet Nut?

The fundamental question when using a rivet nut is determining the compatible material thickness. Unlike a simple bolt, a rivet nut relies on deforming its body (bulbing) behind the material to create a secure, threaded anchor. Rivet nuts have a specified "grip range", which is the minimum and maximum material thickness they are designed to work with effectively. Exceeding the maximum grip range prevents the rivet nut from properly bulbing, leading to a weak or failed installation. Conversely, material thinner than the minimum grip range won't provide enough support for the bulb to form securely against. For steel, common rivet nuts typically handle thicknesses from 0.5 mm (0.020") up to about 6.0 mm (0.236"), depending heavily on the specific size, type, and material of the rivet nut itself. Always consult the manufacturer's specifications for the exact grip range of your chosen rivet nut.

Selecting the Right Rivet Nut: Key Factors

1. Size & Grip Range: This is paramount. The rivet nut's diameter (e.g., M3, M4, M5, M6, M8, M10, 1/4", 5/16", 3/8") and length must correspond to the required thread size and the actual thickness of your steel sheet. The length directly determines the grip range. Choosing a rivet nut with a grip range encompassing your material thickness ensures the bulb forms correctly. Remember, the force required (mandrel break load) increases significantly with thicker steel and larger rivet nut sizes.

2. Material: The rivet nut material must be compatible with the steel and the environment.

• Steel: Strong, economical. Use where corrosion isn't a primary concern or when plating/zinc coating is sufficient. Ideal for thicker steel applications needing high strength.

• *Stainless Steel (A2/A4):* Excellent corrosion resistance, good strength. Best for harsh environments or where galvanic corrosion with the steel base is minimized.

• Aluminum: Lightweight, good corrosion resistance, lower strength than steel. Suitable for lighter loads or where weight is critical. Be mindful of galvanic corrosion potential against steel.

• Copper/Brass: Primarily used for electrical conductivity or specific corrosion resistance needs. Lower strength.

3. Surface Finish: Protects the rivet nut and sometimes the steel, and can affect appearance.

• Zinc Plating (Clear, Yellow, Black): Common, economical corrosion protection for steel rivet nuts.

• Geomet® (Zinc-Flake): Superior corrosion resistance compared to standard zinc plating.

• Passivation: Used on stainless steel rivet nuts to enhance the natural oxide layer and improve corrosion resistance.

• Anodizing: Primarily for aluminum rivet nuts, providing color and enhanced corrosion resistance.

• Plain/Unfinished: Typically stainless steel or aluminum, relying on base material properties.

4. Type & Head Style: Choose based on accessibility and required finish/flushness.

   Blind Rivet Nuts:
   

• Countersunk Semi-Hexagonal Blind Rivet Nut

• Round Head Semi-Hexagonal Blind Rivet Nut

• Countersunk Full Hexagonal Blind Rivet Nut

• Round Head Full Hexagonal Blind Rivet Nut

• Countersunk Knurled Blind Rivet Nut

• Round Head Knurled Blind Rivet Nut

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Through Hole Rivet Nuts:

• Countersunk (Flat Head) Semi-Hexagonal Rivet Nut: Sits flush; hex prevents rotation during bolt tightening.

• Round Head Semi-Hexagonal Rivet Nut: Protrudes slightly; hex prevents rotation.

• Countersunk (Flat Head) Full Hexagonal Rivet Nut: Sits flush; full hex provides maximum rotation resistance.

• Round Head Full Hexagonal Rivet Nut: Protrudes; full hex for max rotation resistance.

• Countersunk (Flat Head) Knurled (Raised Ribs) Rivet Nut: Sits flush; knurling grips material to resist rotation.

• Round Head Knurled (Raised Ribs) Rivet Nut: Protrudes; knurling resists rotation.

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• Blind Rivet Nuts and Through Hole Rivet Nuts(Access Only to One Side - MOST COMMON): Same head styles as above, but designed to install from one side only. Crucial when you cannot access the back of the steel panel.

Conclusion
Successfully using a rivet nut in steel hinges on matching the fastener's grip range to your material's thickness and selecting the appropriate rivet nut type, size, material, and finish for the application's demands. Always prioritize the manufacturer's grip range specifications over generic charts. For blind-side applications, the single-sided installation capability of a blind rivet nut is indispensable. By carefully considering all these factors – thickness, grip range, size, material, finish, and head style – you ensure a strong, reliable, and durable threaded insert in your steel sheet or structure.