Rivet Nut & Blind Nut Guide for Hollow Metal Frames | Sinsun
Rivet Nuts / Blind Nuts / Threaded Inserts for Hollow Metal Frames
Industrial manufacturing, metal fabrication, and commercial assembly have always dealt with hollow metal frames and blindside applications. Weak threads, thin walls, and inaccessible back sides hinder traditional fastening methods.
● Welding a nut inside a hollow section requires both‑side access, distorts thin metal, and adds high labor cost.
● Clinch nuts (PEM‑style) also need backside access and an expensive press.
● When self-tapping screws are used in thin sheets less than 1.5 mm thick, they are highly prone to stripped threads (thread damage) and have poor pull-out resistance.
● Standard nuts and bolts cannot be used if the back is sealed or inaccessible.
There is no thread provided by pop rivets, so they are permanent.
The rivet nut (also called blind nut or threaded insert) solves all these problems. It installs from one side, creates a strong reusable thread, and protects thin metal from deformation. Below is a direct comparison with traditional methods.
| Fastener Type | One‑Side Installation | Reusable Thread | Thin‑Wall Friendly | Tool Cost | Typical Pull‑Out Strength (M6 in 2mm steel) |
| Weld nut | No | Yes | Poor (heat distortion) | High | 4,000–6,000 N |
| Clinch nut (PEM®) | No | Yes | Yes | Medium‑High | 3,000–5,000 N |
| Self‑tapping screw | Yes | No | Poor (strips) | Low | 500–1,500 N |
| Pop rivet | Yes | No | Yes | Low | N/A (no thread) |
| Rivet nut / Blind nut / Threaded insert | Yes | Yes | Yes | Low‑Medium | 5,000–8,000 N |
Core Advantages of Rivet Nuts for Hollow & Blind Assembly
Professional Single‑Sided Blind Installation
Normally, the back side of hollow metal frames, aluminium profiles, equipment casings, and closed pipe structures is not accessible. Rivet nuts completely solve this problem by being installed only from the outer surface. Workers can perform the entire process without touching the inner cavity – ideal for blind threaded fastener for hollow steel frames.
Protect Thin‑Wall Metal from Deformation & Damage
Thin metal panels can be easily cracked, torn or burnt by direct tapping or welding. The rivet nut when installed expands uniformly and seats tightly against the wall of the hole spreading bearing pressure over a large area. This avoids deformation of the substrate, slippage of the thread and damage to the structure, greatly reducing the product scrap rate.
Reusable Standard Thread for Easy Maintenance
Rivet nuts provide standard internal threads after installation, unlike pop rivets which are a permanent fastener. The mating bolts can be removed and re-installed many times – ideal for equipment inspection, component replacement and product upgrades. This avoids the expense of later repair and replacement.
High Efficiency for Mass Industrial Production
Rivet nuts are compatible with both hand and pneumatic riveting tools. Operation is simple, setting is fast, and installation effect is consistent. No welding. No secondary hole cleaning. No polishing. This greatly increases the efficiency of assembly for wholesale bulk orders of rivet nuts.
Diversified Materials for Long‑Term Anti‑Corrosion Performance
Rivet nuts are available in zinc plated carbon steel, stainless steel (304/316) and aluminium alloy, to suit different metal frame materials and prevent electrochemical corrosion. For outdoor use, choose corrosion resistant rivet nut with stainless steel material and passivation treatment for outdoor or coastal use.
Professional Tool & Die Matching Guide
Even the best fasteners need the right tools for installation. Most damage to fasteners and loose connections on-site is due to the improper use of universal tools. Rivet nut / blind nut / threaded insert standard tool matching scheme is shown below.
Manual Hand Tools for Small Batches
Hand-held manual rivet nut tools are portable and lightweight. They are ideal for manual rivet nut tool for small batch applications: on-site renovation, outdoor engineering installation and small workshop processing. For sizes M3 to M8 .
Pneumatic Rivet Nut Guns for Mass Production
Pneumatic rivet nut guns are the ideal choice for factory batch assembly lines. They provide stable pulling force and high efficiency, greatly shorten the assembling cycle. These pneumatic blind nut gun for mass production models are for M4 to M12 and can set 20-30 nuts per minute.
Hydraulic Tools for Large Diameters or High‑Strength Materials
Hydraulic tools provide consistent setting of stainless steel rivet nuts or sizes M10 and above without damaging the threads.
All our tools are provided with hardened mandrels and nose pieces matching each size from M3 to M12, avoiding nut head deformation, thread extrusion and unstable locking.
Choose the Right Rivet Nuts for Your Application
Not all rivet nuts are the same. Depending on the assembly requirements – waterproofing, anti‑rotation, or load distribution – you can select from the following specialized designs.
1.Closed End vs Open End Rivet Nuts – Sealing and Waterproofing
Closed end rivet nuts (also known as sealed blind nuts) are completely closed on the bottom. This design stops moisture, dust and air from passing through the fastener making them ideal for use into outdoor electrical enclosures, automotive underbody components, marine equipment and any application needing waterproof blind nut for outdoor use.
Open end rivet nuts have a hole through them for the bolt to go all the way through the nut. They are suitable for normal blind threading where sealing is not required. They are marginally easier to mount as there is no trapped air to interfere with the setting process.
When to choose which:
Use closed end for waterproof, dustproof, or pressurized systems.
Use open end for general blind threading in dry, indoor environments.
2. Knurled Shank vs Hex Body vs Slotted Shank – Anti‑Rotation for Soft Materials
If you’re installing a rivet nut in soft materials like aluminium, plastic, fibreglass or wood, the nut can spin inside the hole as you tighten the bolt. Special shank designs do not allow this.
The rivet nut with knurled shank rivet nut has a series of straight or diagonal knurls rolled into the body. These grooves dig into the wall of the hole and increase the friction and resistance to rotation. Best on moderately soft metals and plastics.
Hex body rivet nut (full or half hex) with a hexagonal cross section. The six corners cut into the hole wall give the highest anti-rotation torque. Ideal for very soft material like pure aluminium, nylon or thin plastic panels. Full hex body for maximum grip . Half hex body for easier install but effective .
The slotted shank rivet nut has one or more longitudinal slots. When the edges of the slot bite into the substrate and prevent spin. This design is usually used in composite or thin walled materials.
Recommendation: Always use hex body rivet nuts when working with plastic or fibreglass. Knurled shank is generally good enough for aluminium sheets.
Common Installation Mistakes & Professional Solutions
Even with high‑quality fasteners, irregular tool matching and incorrect operation lead to installation failure. Here are the most common on‑site problems and how to solve them.
| Mistake | Consequence | Solution |
| Using a universal pop rivet gun | Insufficient stroke and wrong die size squeeze the rivet nut thread, causing unsmooth bolt assembly or scrapping. | Use a dedicated rivet nut tool with size‑matched mandrel and nose piece. |
| Oversized or irregular hole | Loose press‑fit; the insert falls off after short use. | Use a precision punch and die set to drill a standard‑diameter hole. |
| Applying ordinary tools to sealed blind nuts | Extrusion cracks the closed bottom, destroying waterproof and anti‑corrosion performance. | Equip a dedicated long‑stroke blind nut pull gun to protect the sealed structure. |
| Material thickness outside the grip range | Bulge forms incorrectly; nut is loose. | Always check the grip range specification before ordering. Test on scrap first. |
For more information on surface treatment and coating compatibility, ask us about our corrosion resistant rivet nut for outdoor use options.
Installation Checklist – Installation Steps
Drill the correct size hole.Use the hole specified by the manufacturer.Deburring hole for rivet nut installation strongly recommended – sharp edges can prevent flush seating.
●Select the correct mandrel and nose piece for the rivet nut size.
●Ensure the material thickness falls within the fastener’s grip range.
●Insert the rivet nut into the hole and thread it onto the mandrel.
●Actuate the tool fully until the mandrel automatically releases (for pneumatic tools) or you feel a distinct stop (for manual tools).
●Inspect: The head should be flush (or countersunk) to the surface, and the blind‑side bulge should be uniform.
Common errors to avoid:
●Hole too large → fastener spins in place.
●Material too thin for grip range → loose nut.
●Over‑setting → deformed threads.
Always test on a scrap piece before starting the actual production run.
Why Buy from Sinsun Fasteners?
We manufacture and stock a full line of rivet nuts / blind nuts / threaded inserts for B2B customers – metal fabricators, OEMs, electrical panel builders, HVAC manufacturers and hardware distributors.
What we offer:
● Sizes: M3 to M12 (metric) and imperial equivalents
● Head styles: flat, countersunk, thin, dome
● Body types: round, knurled, hex
● Materials: zinc‑plated carbon steel, stainless steel (304/316), aluminum
● Packaging: boxes, cartons, pallets; custom labeling
● Installation tools: manual, pneumatic, and hydraulic – with matching mandrels and nose pieces
● Sample packs available for testing before bulk orders
Need a Reliable Thread in Hollow Metal Frames?
Add rivet nuts / blind nuts / threaded inserts to your standard parts list when you manufacture sheet metal enclosures, light steel frames, electrical cabinets or any hollow section assembly. They are superior to any other alternative for the blind-threading problem – from one side, with simple tools, and at lower total installed cost than welding or clinch fasteners.
Call us for a wholesale rivet nut or custom size order. Order a sample pack today. Please provide your material thickness, thread size and environment. We’ll send you the fasteners we recommend, along with matching mandrels, so you can test them on your own assembly line.
Looking for other formats? Check out our Insert Rivet Nut page for alternative designs.