Carbon Steel Flat Head Rivet Nut M3–M12 — Countersunk Semi-Hex Blind Rivnut Nutsert

Carbon steel countersunk flat head blind rivet nuts (rivnuts / nutserts) provide a flush, low-profile threaded insert in thin sheet metal and steel panels from one side only. The countersunk flat head sits completely flush with the panel surface — lower profile than a standard flat head rivnut — making these the correct choice for applications where even a small protrusion would interfere with mating surfaces, gaskets, or sliding components.

Key Specifications

Parameter	Value
Material	Carbon Steel (zinc-plated)
Head Style	Countersunk flat head (90° CSK, fully flush)
Body Style	Semi-hex (anti-rotation)
Thread Type	Metric (M3, M4, M5, M6, M8, M10, M12)
Installation	Blind (one-side, rivet nut tool required)
Min. Sheet Thickness	0.5mm (M3) — 1.0mm (M12)
Standard	DIN 7338 / ISO 15977

Why Choose Countersunk Flat Head Rivet Nuts?

Fully flush countersunk head — 90° countersunk head sits completely flush with panel surface; zero protrusion for mating surfaces, gaskets, and sliding components
Semi-hex body — anti-rotation geometry prevents spinning during bolt installation
Blind installation — installs from one side only; no rear access required
Carbon steel (zinc-plated) — economical for indoor and dry environment sheet metal fabrication
M3–M12 range — covers electronics (M3–M6) through structural sheet metal assembly (M8–M12)

Typical Applications

Sheet metal enclosure panels where flush surface is required for gasket sealing (M4–M8)
Sliding door and panel track assembly where protrusions would cause interference (M4–M8)
Automotive body panel flush threaded insert (M6–M12)
PC case and server chassis flush threaded insert (M3–M6)
HVAC ductwork and sheet metal panel flush fastening (M6–M10)
Industrial machinery steel frame flush threaded insert (M8–M12)

Compatible With

Standard rivet nut tools with M3–M12 mandrel sets
90° countersink drill bit for correct flush seating of countersunk head
Sheet materials: mild steel, aluminium (min. 0.5mm)
Mating bolts: ISO 4762 hex socket cap screws, DIN 933 hex bolts M3–M12

Package Contents

Carbon steel countersunk flat head rivet nuts in selected size and quantity (per variant)
Note: rivet nut installation tool sold separately

Frequently Asked Questions

Q: What is the difference between a flat head and a countersunk flat head rivet nut?: A: A standard flat head rivet nut has a flat collar that sits on top of the panel surface with a small protrusion. A countersunk flat head rivet nut has a 90° bevelled head that sits in a countersunk hole, resulting in zero protrusion — completely flush with the panel surface.
Q: Do I need to countersink the hole before installing?: A: Yes. Use a 90° countersink drill bit to prepare the hole before installing a countersunk flat head rivet nut. The countersink allows the head to sit flush with the panel surface. Without countersinking, the head will protrude above the surface.
Q: When should I use countersunk vs standard flat head rivet nuts?: A: Use countersunk flat head rivet nuts when the panel surface must be completely flush — for example, where a gasket must seal against the surface, where a mating panel slides over the surface, or where aesthetics require zero protrusion. Use standard flat head rivet nuts for general applications where a small protrusion is acceptable.