What is a rivet nut?
A rivet nut — also called a rivnut, nutsert, nut insert, or blind rivet nut — is a hollow, internally threaded fastener that installs into a pre-drilled hole from one side only and expands on the blind side to grip the material. Once set, it gives you a permanent threaded point in sheet metal, aluminium, fibreglass, plastic, or thin-wall tube — without needing access to the back face, and without welding.
The name causes some confusion. "Rivet nut", "rivnut", "nutsert", and "nut insert" all refer to the same product. The term "nut rivet" is sometimes used in trade, though technically imprecise — the nut is the insert, not the rivet. For this guide we use "rivet nut" and "rivnut" interchangeably.
The mechanism is straightforward. You load the rivnut onto a mandrel tool, push it into the hole, and squeeze or pull the tool. The mandrel pulls the threaded body upward, causing the shank to buckle outward and form a flange on the blind side. That flange clamps the material between itself and the head flange, locking the nut in place. You then thread a bolt through from the access side.
When do you need a rivet nut?
Use a rivnut when:
- The material is too thin to tap a thread directly (typically under 3–4 mm)
- You only have access to one side of the panel or tube
- The material cannot be welded (aluminium sheet, fibreglass, plastic, composite)
- You want a removable, bolted connection rather than a permanent pop rivet
- You need to add a threaded point to an existing structure without disassembly
Common applications include body panels and accessories on vehicles, mounting racks and brackets on van conversions, electronics enclosures, marine fittings, furniture assembly, and sheet metal fabrication.
Rivet nut vs pop rivet — what's the difference?
A pop rivet (blind rivet) permanently joins two pieces of material together — the rivet itself is the fastener, and once set, it cannot be removed without drilling out. A rivet nut does the opposite: it creates a reusable threaded socket in the material so you can bolt and unbolt something repeatedly.
If you want to mount a bracket that you might need to remove later — a roof rack, an instrument panel, a cable tray — a rivet nut is the right choice. If you're permanently joining two sheets of metal and removal is not required, a pop rivet is faster and cheaper.
For more on blind rivets and how to choose between rivet types for permanent joining, see our Types of Rivets Guide.
Types of rivet nuts
Rivet nuts come in several body configurations. Choosing the right type for your application is just as important as choosing the right size — the wrong type can spin, pull out, or fail to set correctly.
Round body vs hex body
Round body rivet nuts have a cylindrical shank. They are the most common type and work well in steel, where the expansion force of the set fastener is enough to grip the hole wall. The limitation is torque resistance — in softer materials (aluminium, plastic, fibreglass), a round body can spin in the hole when you tighten a bolt against it.
Hex body rivet nuts have a hexagonal shank that cuts into the hole wall during installation, preventing rotation. Use hex body when working in aluminium sheet, fibreglass, or any material where a smooth round body would not grip reliably. For blind-side torque resistance in demanding applications, hex body is the correct choice.
Knurled / ribbed shank vs smooth shank
Knurled or ribbed shank rivet nuts have longitudinal ribs along the body that bite into the hole wall as the fastener sets. They offer significantly better anti-rotation performance than smooth round-body fasteners — without requiring the exact hole shape that a hex body needs. Ribbed shanks are a good middle ground: easier to install than hex body (round hole is fine), and much more resistant to spinning than plain smooth body.
Smooth shank suits standard applications in steel where hole tolerances are precise and spin-out is not a concern.
Open end vs closed end
Open end rivet nuts have an open thread on both the head and the blind side — they allow a bolt to pass through fully, and they are the standard type for most applications.
Closed end rivet nuts are sealed at the blind end. Use closed end when:
- The blind side is exposed to water, dust, or contaminants
- A gas-tight or liquid-tight seal is required
- The fastener is going into a tube or sealed section
Typical applications for closed end: marine fittings, outdoor enclosures, food processing equipment, and any installation where contamination from behind would be a problem.
Low-profile / AET style
Standard rivet nuts form a bulge flange on the blind side as they set. In some situations — installing into round tubing, shallow blind pockets, or tight assemblies — there is not enough clearance for that bulge.
The low-profile (AET) style works differently: the tool separates the body into two halves, expanding the lower section radially to grip the hole wall rather than forming a back flange. This means the installed height on the blind side is minimal. Use low-profile rivet nuts for installations in square or round tubing, where you cannot create clearance for a conventional buckle flange.
Floating rivet nut
A floating rivet nut has a threaded insert that can shift laterally within the outer body — typically ±0.5 mm to ±1 mm in each direction. This is used when bolt hole alignment is critical but panel-to-panel tolerances are not tight enough to guarantee perfect registration. Common in automotive assembly, electrical cabinet manufacture, and electronics enclosures where multiple bolts must line up across several panels.
Rivet nut sizes and grip ranges
The two most important dimensions when selecting a rivet nut are the thread size and the grip range. Get either wrong and the fastener will either fail to set or will not hold adequately.
Metric thread sizes
Rivet nuts in Australia are predominantly metric. The most common sizes in trade and industrial use are M3 through M12. The table below gives standard dimensions and hole sizes for round-body rivet nuts — always check the manufacturer's data sheet for the specific product you are using, as dimensions vary slightly between brands.
| Thread Size | Body OD (mm) | Drill Hole (mm) | Head Flange OD (mm) | Typical Grip Range (mm) |
|---|---|---|---|---|
| M3 | 5.0 | 5.1 | 8.0 | 0.5 – 2.5 |
| M4 | 6.0 | 6.1 | 9.0 | 0.5 – 3.0 |
| M5 | 7.0 | 7.1 | 11.0 | 0.5 – 3.0 |
| M6 | 9.0 | 9.1 | 14.0 | 0.5 – 3.5 |
| M8 | 11.0 | 11.1 | 16.0 | 0.5 – 4.0 |
| M10 | 13.0 | 13.1 | 18.0 | 1.0 – 5.0 |
| M12 | 16.0 | 16.1 | 22.0 | 1.5 – 6.0 |
Note: Imperial thread sizes (UNC and UNF) are available for use with older Australian equipment, American-specification vehicles, and some agricultural machinery. Common imperial rivnuts include 10-32 UNF, 1/4-20 UNC, 5/16-18 UNC, and 3/8-16 UNC. If you are working on newer Australian or European vehicles or machinery, metric is almost certainly correct.
Understanding grip range
Grip range is the range of material thicknesses the rivet nut is designed to clamp. A rivnut specified for a grip range of 0.5–3.0 mm will set correctly when the total panel thickness is between 0.5 mm and 3.0 mm.
This matters enormously in practice:
- Under minimum grip: The rivet nut will not form a proper back flange. It will feel loose, may spin, and will have poor pull-out strength.
- Over maximum grip: The tool cannot pull the mandrel far enough to set the fastener. You will strip the mandrel or crush the body without forming a proper flange.
- Mid-range is best: Aim for the middle of the grip range for the most consistent set and highest pull-out force. If your panel is 1.5 mm thick, use a rivnut with a grip range centred around 1.5 mm — not one rated 0.1–3.0 mm where 1.5 mm is at one extreme.
Many suppliers specify a "short grip" and "long grip" variant of each thread size — use short grip for thin sheet, long grip for thicker substrates or stacked panels.
How to read a rivet nut part number
Part numbers vary by manufacturer but typically encode: body material / thread size / body length / body style / shank type. For example, a part number like RN-M6-SS-H-C might decode as: Rivet Nut / M6 thread / Stainless Steel body / Hex body / Closed end. Always confirm against the manufacturer's catalogue — there is no universal standard for part number format.
Rivet nut materials
The body material of the rivet nut determines its corrosion resistance, strength, and compatibility with the substrate. Use the wrong material and you risk galvanic corrosion, insufficient strength, or a body that is too hard to set properly.
Aluminium
Aluminium rivet nuts are lightweight and corrosion-resistant, and they are the best choice for aluminium panels and structures — using an aluminium rivnut avoids the galvanic couple that would occur between a steel fastener and an aluminium substrate. They are also the right call in plastic, fibreglass, and other soft materials where the softer body deforms more easily during setting.
Limitation: lower pull-out and shear strength than steel. Not suitable for high-load structural applications.
Steel (zinc-plated or plain)
Steel rivet nuts are the standard workhorse for general industrial, fabrication, and automotive work in steel substrates. Zinc plating provides moderate corrosion resistance — adequate for indoor or semi-sheltered environments. Not suitable for marine, food processing, or outdoor applications where sustained moisture or chemical exposure is expected.
Stainless steel (304 / 316)
Stainless steel rivet nuts are the right choice for marine, food-grade, and outdoor applications. Grade 316 stainless provides superior resistance to chloride corrosion (salt water). More difficult to set than aluminium or mild steel — requires a good quality tool, correctly adjusted, and slightly more force. If your tool is struggling to set stainless rivnuts, check that the mandrel stop is set correctly and that you are using the right grip range.
Brass
Brass rivet nuts are used primarily in plastic substrates, electrical enclosures, and electronics assemblies. Brass is soft enough to set without damaging fragile base materials, is non-magnetic, and provides good thread quality for fine threads. Also used in PCB and panel assemblies where electrical conductivity at the fastener point is required.
Rivet nut tools — hand, air, and DIY methods
Setting a rivet nut correctly requires the right amount of pull force, applied consistently. The tool you choose determines whether you can achieve that reliably — and how quickly.
Hand rivet nut tool
A hand rivet nut tool (also called a nut rivet gun) operates by squeezing the handles together, which pulls the mandrel and sets the fastener. Most hand tools accept interchangeable mandrel heads to suit different thread sizes — typically M3 through M12 are covered with a set of three to four mandrels.
Hand tools are the right choice for site work, occasional use, small volumes, and anywhere compressed air is not available. Look for:
- A mandrel depth stop that can be adjusted per fastener size — this controls how far the mandrel pulls and prevents over-crush
- A knob or release mechanism to back the mandrel out of the set fastener
- Handles long enough to generate adequate force for M8 and M10 in steel or stainless
A well-set hand tool will handle M3–M8 in aluminium and steel comfortably. For M10–M12 stainless, a pneumatic tool is a better choice if you have volume work.
Pneumatic / air rivet nut tool
Air-powered rivet nut tools set fasteners faster and with more consistent force than hand tools, making them the right choice for production line work, bodyshop use, or any situation where you are setting more than 20–30 rivnuts per day. They also reduce operator fatigue significantly when working with M8 and above in steel or stainless.
Pneumatic tools require a compressor capable of sustaining the tool's rated CFM at the required pressure — typically 6–7 bar (90–100 psi) and 3–5 CFM. Most air rivet nut tools are also adjustable for mandrel stroke, which is critical for setting different sizes correctly.
DIY method — bolt and two nuts
If you do not have a rivet nut tool and need to install one or two fasteners in a pinch, the bolt-and-two-nuts method works as follows: thread a bolt through the rivet nut, then thread two nuts onto the end of the bolt and tighten them against each other (jam nut). Insert the rivet nut into the hole, hold the bolt head stationary, and tighten the inner nut with a spanner — pulling the rivet nut body up to set it. Once set, loosen and remove the bolt assembly.
This method works but has limitations: it is slow, the setting force is inconsistent (difficult to judge when the fastener is properly set), and it is easy to over-crush smaller rivnuts. Use it only for one-off situations. For any volume of work, the correct tool is worth the investment.
Setting the mandrel depth stop
Regardless of which tool you use, setting the mandrel depth stop correctly for each fastener size is critical. The depth stop determines how far the mandrel travels on each stroke — too little travel and the fastener is under-set (weak, likely to spin); too much and you over-crush the body or strip the thread.
The correct method: thread a rivet nut onto the mandrel, insert it into a scrap piece of the same material thickness you will be working in, set the fastener, and inspect the back side. The back flange should be even and fully formed, with the body not excessively crushed. Adjust the stop and repeat until the set is consistent. This takes five minutes on a scrap piece — it is not optional.
How to install a rivet nut — step by step
The following steps assume you are using a hand rivet nut tool. The process is the same for an air tool; the pneumatic tool handles the pull force automatically once triggered.
What you will need
- Rivet nut tool with correct mandrel for your thread size
- Drill and correct drill bit (see sizing table above)
- Deburring tool or step drill
- Centre punch and hammer
- Rivet nuts (correct size, material, and grip range for your application)
- Bolt to test thread engagement after setting
- Safety glasses — mandatory when drilling and setting
For drilling noise, consider hearing protection if working in an enclosed space or with a noisy drill.
Step 1 — Mark and centre punch
Mark the hole position clearly and use a centre punch to create a dimple. The punch prevents the drill bit from wandering when you start the hole, which is critical — an off-centre or oversize hole will cause the rivet nut to sit crooked or spin.
Step 2 — Drill to the correct hole size
Use the drill size from the manufacturer's data sheet for your specific rivet nut (refer to the sizing table above for standard dimensions). The hole should allow the rivet nut body to fit snugly — hand pressure to push it in is fine, but it should not drop through freely. Any play in the hole becomes play in the installed fastener.
Drill perpendicular to the surface. A crooked hole produces a crooked fastener, which puts uneven load on the thread and the set flange.
Step 3 — Deburr both sides of the hole
This step is skipped constantly and causes more spinning rivnuts than any other single mistake. Drilling produces a burr on the exit face of the hole. If that burr is not removed, the rivet nut's back flange clamps against a raised ring of raised, weakened material — not the flat panel face. The result is low pull-out strength and a fastener that spins with minimal torque.
Use a deburring tool, a countersink bit run lightly by hand, or the point of a step drill to clean both the entry and exit faces. The surface around the hole should be flat and smooth.
Step 4 — Set the mandrel depth stop
If you have not already done so, set the tool's depth stop using a scrap piece of the same material. Thread a rivet nut onto the mandrel, insert into the scrap hole, set it, and inspect the back flange. Adjust until the set is clean and consistent before moving to the actual workpiece.
Step 5 — Load the rivet nut onto the mandrel
Thread the rivet nut onto the mandrel until the head flange is flush against the tool nose, with the rivet nut body protruding forward. The nut should protrude far enough to engage the workpiece properly — check the manufacturer's guidance for the specific tool and fastener combination.
Step 6 — Insert and set
Push the rivet nut firmly into the hole so the head flange sits flat against the surface. Hold the tool perpendicular to the panel — any angle will produce an uneven back flange. Squeeze the handles fully (or trigger the air tool) until you feel the resistance change — the characteristic "click" or increase in resistance indicates the fastener has set.
Do not release and re-squeeze. Setting a rivnut in two partial strokes produces an inconsistent back flange. If your hand tool requires more force than you can generate in a single stroke for larger sizes, switch to a two-handed grip or upgrade to a pneumatic tool.
Step 7 — Remove the tool
Turn the knob or release mechanism on the tool to back the mandrel out of the set rivet nut. On well-set fasteners this should be smooth. If the mandrel is difficult to remove, the fastener may have been over-crushed — inspect the thread before proceeding.
Step 8 — Inspect and test
Thread a bolt of the correct size into the installed rivet nut by hand. It should engage cleanly with no binding or cross-threading. Check that the rivet nut does not rotate when you apply moderate torque — any rotation indicates the fastener has not set correctly (see troubleshooting section below).
Inspect the back flange if accessible — it should be even and fully formed with no cracks.
Tips and tricks
- Chase the threads after setting: Run a tap of the matching size through the installed rivnut and apply a small amount of anti-seize to the bolt. Setting deformation can slightly distort the threads — a tap cleans them up and ensures smooth engagement. See our lubricant guide for anti-seize product recommendations.
- Practice on scrap first: Every time you start on a new material thickness or switch rivet nut size, run three to four fasteners into a scrap piece of the same material before working on the actual component. This confirms your hole size, grip range, and tool setting before you commit.
- Keep mandrels clean: Built-up aluminium or steel debris on the mandrel thread causes inconsistent engagement and can jam the tool. Clean mandrels with a wire brush and a drop of oil periodically.
Common mistakes and troubleshooting
My rivnut is spinning when I tighten the bolt
Spinning after installation is the most common rivet nut failure. The causes, in order of likelihood:
- Hole too large: Even 0.3–0.5 mm oversize removes the interference fit between the body and the hole. The fastener has no lateral grip and spins freely. Drill a new hole in an adjacent position with the correct bit size.
- Deburring skipped: Back flange clamped on a burr, not the panel. The burr collapses under torque, the fastener rotates. Drill out, clean the back face, re-install.
- Under-set: Mandrel stop not adjusted far enough. The back flange did not fully form. Correct the tool setting, drill out the failed fastener, and re-install in a new hole.
- Wrong body type for material: Smooth round body in soft aluminium or plastic. Switch to ribbed shank or hex body.
- Grip range mismatch: Panel is thinner than the minimum grip of the fastener. The body buckled but did not clamp the panel. Use a rivnut with the correct grip range for your material thickness.
If a spinning rivnut cannot be drilled out cleanly, centre punch the middle of the insert and use a left-hand twist drill bit — the left-hand rotation often winds the spinning insert out as you drill.
The mandrel snapped or stripped
Usually caused by over-torquing with a hand tool or using an incorrect mandrel size for the rivnut thread. Check that the mandrel threads match the rivet nut thread pitch exactly. Replace mandrels when they show wear — a worn mandrel strips easily at the thread engagement point.
The rivet nut pulled through the panel
Pull-through indicates the back flange area is insufficient for the load applied — either the material is too thin, too soft, or the rivnut is too small for the bolt load. Solutions: increase the rivet nut head flange size (large-flange variants available for M5–M10), use a backing washer on the blind side, or use a larger thread size. For general guidance on washers and load spreading, see our Types of Washers Guide.
The thread is damaged after setting
Over-crushing the rivet nut distorts the threaded body. This is most common with smaller sizes (M3, M4) where the mandrel stop was set too deep. If threads are damaged, drill out and replace. Calibrate the tool depth stop carefully on scrap before re-installing.
Rivet nut vs weld nut — when to use which
A weld nut is permanently welded to the base material before assembly. A rivet nut is installed after fabrication, from one side. The right choice depends on your material, access, equipment, and load requirements.
| Factor | Rivet Nut | Weld Nut |
|---|---|---|
| Access needed | One side only | Both sides (for welding) |
| Material | Steel, aluminium, plastic, fibreglass, composites | Steel and weldable metals only |
| Equipment needed | Drill + rivet nut tool | Welder + PPE |
| Heat distortion risk | None | Yes — heat affected zone around weld |
| Removable / reworkable | Yes (drill out and replace) | No — permanent |
| Pull-out strength | Moderate (load-rated per size) | High — structural if welded correctly |
| Best for | Retrofit, thin sheet, non-weldable materials, post-assembly fitment | Structural, high-load, production line fabrication |
For most trade and maintenance applications — van fitouts, panel work, equipment mounting, light fabrication — a rivet nut is the faster, more flexible, and safer choice. Weld nuts are preferred in structural applications (chassis, heavy brackets, high-vibration environments) where the permanent bond and higher load rating justify the welding step.
For a full rundown on nut types including weld nuts, cage nuts, and flange nuts, see our Types of Nuts Guide.
Shop rivet nuts and tools at AIMS Industrial
AIMS Industrial stocks a range of rivet nuts across metric thread sizes M3 to M12 in aluminium, steel, and stainless steel — including round body, hex body, and closed-end variants. We also carry rivet nut tools to suit everything from occasional DIY fitments to regular trade use.
- Browse our full fasteners range — rivet nuts, bolts, nuts, washers, and more
- Shop rivet nut tools — hand tools and accessories
Need advice on the right size, material, or tool for your job? Contact our team on (02) 9773 0122 or email sales@aimsindustrial.com.au.
Frequently asked questions — rivet nuts and rivnuts
What is the difference between a rivet nut and a nutsert?
Rivet nut and nutsert are two names for exactly the same product. Other common names include rivnut, nut insert, and blind rivet nut. All refer to a hollow internally threaded fastener that installs into a pre-drilled hole from one side and expands on the blind side to create a permanent threaded anchor point.
Are rivets and rivnuts the same thing?
No. A standard pop rivet (blind rivet) permanently joins two pieces of material together — it has no internal thread and cannot be used with a bolt. A rivnut (rivet nut) creates a reusable threaded socket in the material so you can bolt and unbolt something repeatedly. They share a similar installation principle but are completely different fasteners serving different purposes.
What are the disadvantages of using rivnuts?
The main disadvantages are: lower pull-out strength compared to welded nuts; susceptibility to spinning if incorrectly installed or if the hole is oversized; requirement for precise hole sizing (even 0.5 mm oversize can cause failure); and the need for a specific installation tool for consistent results. They are also not suitable for very high-load structural applications where weld nuts are preferred.
What is the difference between open end and closed end rivet nuts?
Open end rivet nuts are unsealed at the blind side — a bolt can pass through fully, and they are the standard type for most applications. Closed end rivet nuts are sealed at the blind end, blocking water, dust, and contaminants from passing through. Use closed end for marine, outdoor, food processing, or any environment where contamination from the blind side is a concern.
Why does my rivnut keep spinning?
Spinning is almost always caused by one of four things: the drilled hole is slightly too large (even 0.3–0.5 mm oversize causes loss of grip); the burr on the back face of the hole was not removed before installation (the flange clamps on the burr, not the panel); the fastener was under-set because the tool depth stop was not adjusted correctly; or the wrong body type was used (a smooth round body in soft aluminium or plastic will spin — switch to ribbed shank or hex body).
What size hole do I need for a rivet nut?
The correct hole size is typically 0.1 mm larger than the body OD of the rivet nut — just enough clearance to push the body in by hand without it dropping through. For common metric sizes: M5 requires approximately a 7.1 mm hole, M6 requires 9.1 mm, M8 requires 11.1 mm, and M10 requires 13.1 mm. Always check the manufacturer's data sheet for the specific product, as dimensions vary between brands.
What grip range do I need?
The grip range must match your panel thickness. Measure the total thickness of the material you are fastening into and select a rivet nut with a grip range that includes that thickness — ideally near the middle of the range rather than at the extremes. A rivnut specified for 0.5–3.0 mm will not set correctly in a 0.1 mm panel or a 4 mm panel. Most suppliers offer short grip and long grip variants in each thread size.
Do I need a special tool to install rivet nuts?
A dedicated rivet nut tool is strongly recommended for consistent results. Hand rivet nut tools start from around AUD $50–80 and handle M3–M10 in aluminium and steel. Pneumatic tools suit higher-volume work and M8–M12 in stainless. In an emergency, a bolt and two jam nuts can be used (thread the assembly through the rivnut, insert into the hole, hold the bolt head and tighten the inner nut to draw the body up) — but setting force is inconsistent and it is easy to over-crush smaller sizes.
Can rivet nuts be used in aluminium?
Yes. When installing into aluminium substrate, use aluminium body rivet nuts to avoid galvanic corrosion between dissimilar metals. Hex body or ribbed shank is strongly recommended for aluminium substrate — smooth round-body rivnuts can spin in the softer material. Ensure hole sizing is precise, as aluminium deforms more easily than steel and an oversized hole gives even less grip.
Can rivet nuts be used in plastic or fibreglass?
Yes, with the right selection. Use aluminium or brass body rivet nuts in plastic and fibreglass — steel is too hard and can crack brittle substrates during setting. Hex body or large-flange variants distribute load over a larger area and reduce the risk of pull-through in lower-strength materials. Set carefully with controlled force — plastic and fibreglass can crack if the mandrel stop is too deep.
What is the difference between a round body and hex body rivet nut?
A round body rivet nut has a cylindrical shank — it relies on the expansion force of the set flange to resist rotation. A hex body rivet nut has a hexagonal shank that cuts into the hole wall during installation, providing mechanical anti-rotation resistance. Use round body in steel where interference fit is reliable. Use hex body in aluminium, plastic, fibreglass, and any material where a smooth body would spin under bolt torque.
When should I use a rivet nut instead of a weld nut?
Use a rivet nut when: you only have access to one side of the panel; the material cannot be welded (aluminium sheet, fibreglass, plastic, composite); you want a removable or reworkable fastener; welding equipment is unavailable; or heat distortion from welding would be a problem. Use a weld nut for permanent, high-load structural joints in steel where welding equipment is available and a stronger permanent connection is required.