Industry News
Rivet nuts for thin sheet metal: selection, hole preparation and installation essentials
2026-09-24
Compiled by JIALI Industrial (164.hk) — a Hong Kong fastener supplier specialising in screws, bolts, nuts and selection know-how.
Why threading thin sheet is hard — and where rivet nuts fit
Thin sheet from 0.5 to 3 mm is the mainstay of cabinets, enclosures, solar racking and appliance frames, yet putting a reliable internal thread into it is harder than it looks. Tapping directly: an M5 thread in a 1.5 mm sheet engages only about 3 threads, so pull-out and torque capacity are poor and the thread strips under vibration. Blind sections: the inside of a closed profile or box is simply out of reach for a nut and spanner. Weld nuts: the heat input distorts thin sheet, burns off plating and leaves weld spatter to grind off behind. Self-clinching nuts: they need a press and dedicated tooling, and hard or thick sheet can crack at the clinch. Rivet nuts were designed for exactly these cases: single-sided installation, one stroke of a rivet-nut tool from the front sets the nut and forms the internal thread, with no distortion and no burnt plating — ideal where the back face cannot be reached. Note the distinction from blind rivets covered earlier: a blind rivet only clamps two sheets together and has no thread, while a rivet nut carries an internal thread so a standard bolt can be removed and refitted repeatedly — the mainstream way to create a removable threaded point on sheet metal.
Selection guide: head style, anti-rotation, sealing and material tiers
Settle four dimensions before ordering. Head style: the flat dome head is the general-purpose choice, standing about 1-1.5 mm proud of the sheet; a countersunk head sits flush on visible panels but needs a pre-cut 90-degree recess; small-head variants protrude less and carry slightly less load. Anti-rotation body: a round body with knurls grips through the knurled teeth, but its torque resistance is modest; a hexagonal body resists rotation far better at the cost of a hex-shaped hole — specify hex body for hinge and rail mounting points where torque is high. Sealing: standard open-end rivet nuts have a through bore that lets dust and moisture pass; for outdoor cabinets and liquid-cooled modules choose closed-end types with a sealed base. Materials and standards by environment: zinc-plated steel for dry indoor use; 304 stainless (ISO 3506 A2) outdoors; 316 (A4) for coastal, chemical and food equipment; aluminium bodies for weight-critical designs, minding galvanic corrosion against steel bolts. Governing references: GB/T 17880.1 (flat head) and GB/T 17880.2 (countersunk head) in China, IFI 132 in North America. The two details that go wrong most often are sheet range and hole size: every model suits a specific sheet thickness band (an M5 flat-head round-body nut typically spans 0.5-2.5 mm), and outside that band the body either pulls through or never sets; an oversized hole lets the nut spin during setting, defeating anti-rotation, while an undersized hole will not accept the body. For M5 round knurled bodies the common hole is 6.0-6.1 mm and about 7.0 mm for hex bodies — always confirm against the supplier catalogue.
Installation, acceptance checks and common pitfalls
Installation quality decides the outcome. For small M3-M6 volumes a hand rivet-nut tool is enough; for production runs and M8 and above use a pneumatic tool with the pull force and stroke adjusted to the model. Four steps: deburr the hole and keep it perpendicular, because burrs stop the flange seating flat; load the nut and press the tool square to the sheet — setting at an angle loads the flange on one side and loosens the joint; stop as soon as the stroke completes, since repeated extra pulls over-form the body; then check that the flange is fully seated and crack-free. Accept with four sample checks: a go gauge through every thread so later bolts enter freely; torque sampling, taking the spin-out value from the catalogue and never exceeding it with the installing bolt, or the nut will rotate in its hole; tensile sampling per batch; and visual inspection for cracks and over-forming. Avoid three pitfalls. Pairing a zinc-plated steel rivet nut with aluminium or 304 sheet invites galvanic corrosion that rusts a ring around the hole — match materials to the sheet. Over-torquing the installing bolt is the classic failure: a rivet nut weak point is torque, so add a flat washer to spread the load in heavy joints. And do not reuse old hole-size tables: tolerances differ between makers, so confirm each batch against its catalogue. Need rivet nut selection, samples or matched supply? Contact JIALI Industrial (164.hk) with your sheet thickness and specification.
Related Reading
- Fasteners for food and beverage equipment: hygiene design, washdown corrosion and material certification
- How to choose fasteners for high-temperature service: heat-resistant steels, tempering and failure control
- JIALI launches Stainless Steel zone with full 304 / 316 range
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