Maintenance Guide for Rivet Nut Guns and Threaded Insert Guns
Introduction: why proper maintenance matters
Rivet nut guns and threaded insert guns are workhorses in many industries, from automotive to aerospace and general manufacturing. They allow fast installation of strong threads in thin materials. But just like any tool, they only perform at their best if properly maintained.
A poorly serviced tool leads to broken mandrels, failed joints, downtime, and higher costs. On the other hand, a structured maintenance plan can extend tool life, reduce spare part spend, and improve fastening quality.
What to expect from this Blog?
This guide is written for both operators/technicians (with hands-on checklists and repair tips) and buyers/managers (with cost planning insights). It also explains why many companies using rivet nut and threaded insert guns are switching to friction drilling as a lower-maintenance alternative.
1. Maintenance schedule for rivet nut and threaded insert guns
Regular maintenance keeps your tool accurate and reliable. The table below shows a schedule:
| Frequency | Tasks |
|---|---|
| Daily | - Visual inspection of nosepiece, mandrel, tool body. - Clean mandrel threads (debris, oil, chips). - Check mandrel straightness, replace if bent. - Lubricate mandrel threads with light oil. - Check air supply (drain compressor water, confirm 5–7 bar). - For cordless tools: check battery charge and overheating. |
| Weekly | - Remove and clean nosepieces, check thread wear. - Verify pull force and adjust stroke length/force if needed. - Remove debris inside housing. - Grease pistons/bearings if specified. |
| Monthly | - Inspect mandrel for stripped threads, cracks, bending. - Inspect seals (hydraulic/pneumatic). - Clean or replace filters in FRL unit (pneumatic). - Clean battery contacts, check charger. |
| Every 6–12 months | - Full strip-down and cleaning. - Replace seals, check piston and hydraulic oil. - Send for calibration or professional rebuild if in continuous use. |
2. Common failures and how to fix them
Even with proper care, rivet nut guns and threaded insert guns are subject to wear. Below are the most common issues, their likely causes, and how to fix them:
| Problem | Likely Cause | Typical Repair |
|---|---|---|
| Mandrel breaking/stripping | Overtightened insert, misalignment, fatigue | Replace mandrel. Inspect stroke setting. Retrain operator. |
| Rivet nut not pulling properly | Worn mandrel threads, low pull force, air pressure drop | Replace mandrel, check stroke, inspect seals. |
| Air leaks (pneumatic) | Worn O-rings/seals, cracked hose, loose fittings | Replace seals, re-fit hose/fittings. |
| Hydraulic oil leak | Damaged piston seals, cracked housing | Replace O-rings, refill hydraulic fluid. |
| Tool won’t cycle/reset | Sticking piston, lack of lubrication, air supply issue | Strip, clean, re-grease, replace seals. |
| Weak pull force | Low air pressure, piston seal wear, weak battery | Increase pressure, service piston, replace battery. |
| Battery tools cutting out | Overheated motor, worn brushes, dead cells | Replace brushes or battery pack. |
3. Typical repair procedures
Mandrel replacement
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Unscrew nosepiece.
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Remove damaged mandrel.
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Clean housing.
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Install new mandrel and lubricate threads.
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Reset stroke if adjustable.
Seal replacement (pneumatic/hydraulic)
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Strip tool according to manual.
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Remove piston assembly.
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Replace worn O-rings and seals.
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Re-grease and reassemble.
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Test under pressure.
Hydraulic oil top-up
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Open reservoir, refill with manufacturer-specified oil.
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Bleed air if necessary.
Air system cleaning
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Drain compressor and lines.
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Replace inline filters.
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Check regulator and lubricator.
Battery repair/maintenance
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Clean battery contacts.
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Replace pack if capacity is reduced.
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Inspect motor brushes and replace if worn.
4. Mandrel life expectancy
Mandrels are consumables. Their lifetime depends on material, size, tool type, and operator technique.
| Insert Type & Size | Typical Cycles | Notes |
|---|---|---|
| Aluminium / steel M4–M6 | 3,000–5,000+ cycles | Long life if alignment is correct. |
| Stainless steel M8–M12 | 500–1,500 cycles | Shorter life, sensitive to misalignment. |
| High-volume stainless (M8+) | ~1 mandrel per shift | Some factories plan one mandrel per shift per gun. |
Rule of thumb: stainless inserts shorten mandrel life by up to 70% compared to aluminium or mild steel.
5. Mandrel replacement cost
Mandrel costs vary by size and design.
| Size Range | Typical Cost (€) | Typical Cost (£ / $) |
|---|---|---|
| Standard M4–M8 | 20–40 | £15–30 / $20–40 |
| Large M10–M12 | 40–80 | £35–70 / $40–80 |
| Specialty/custom | 80–120+ | £70–110 / $80–120+ |
For plants running stainless fasteners in high volume, mandrel costs can outweigh the price of the tool itself over its service life.
6. Cost planning and ROI
For maintenance managers and buyers, planning ahead saves money.
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Rotate mandrels → use one in production, another being cleaned.
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Train operators → poor alignment and overtightening drastically reduce mandrel life.
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Track mandrel life → keep a logbook per tool to predict failure points.
With structured planning, plants can cut unplanned downtime by 30–40% and optimize spare part usage.
7. Why competitor users should rethink their approach
If you are currently relying on rivet nut guns or threaded insert guns, you already know the ongoing costs:
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Regular mandrel replacement
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Seal kits
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Oil refills
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Battery pack replacements
These costs accumulate fast. That’s why many manufacturers are switching to friction drilling (Flowdrill) as an alternative:
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Creates a stronger, longer-lasting thread directly in the base material.
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No rivet nuts or inserts required.
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Reduces tool maintenance and consumable costs.
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Streamlines production — fewer parts, fewer failures.
For high-volume users, the total cost of ownership is often lower with friction drilling compared to maintaining fleets of rivet nut or threaded insert guns.
8. Frequently asked questions
How often should I replace a mandrel in a rivet nut gun?
For aluminium and mild steel, mandrels can last thousands of cycles. For stainless steel, expect 500–1,500 cycles depending on operator care.
What causes weak pull force in a threaded insert gun?
Most commonly low air pressure (pneumatic tools), worn piston seals, or a weak battery (cordless).
What is the average cost of maintaining a rivet nut gun?
Depending on usage, mandrels can cost more than the tool itself over its lifetime. Budget €500–€2,000 per year in consumables for high-volume stainless applications.
How can I extend mandrel life? Keep threads clean, align inserts carefully, avoid overtightening, rotate mandrels, and train operators.
Is friction drilling a better alternative?
Yes, especially for high-volume production. It eliminates rivet nuts and inserts, reduces consumable spend, and creates stronger joints with fewer process steps.
Conclusion
Maintaining rivet nut guns and threaded insert guns properly is essential for uptime and fastening quality. Operators should follow daily and weekly checklists, while managers need to plan ahead for mandrel costs and service intervals.
However, if your production line consumes large numbers of mandrels and seals, it’s worth comparing the total cost of ownership with friction drilling. Many manufacturers have already reduced costs and improved quality by eliminating rivet nuts and inserts altogether.
Want to see if friction drilling can work in your application? Contact Flowdrill for expert advice and a free sample.
Changing the way the world achieves stronger and quicker fastening connections.
Flowdrill is a tungsten carbide friction drill that provides a cost effective and reliable connection alternative to traditional fastening methods such as rivet, insert and weld nuts.
