Anti-Loosening Options: Nylon Insert vs All-Metal Lock Nut vs Threadlocker
Bolts loosen through transverse slip, not vibration as such. This comparison covers the three mainstream locking routes - nylon-insert lock nut (DIN985), all-metal lock nut (DIN980) and threadlocker - on transverse-vibration behaviour, remakes, temperature ceiling and relative cost, with a three-step decision path.
Overview
When clamped parts slip transversally, thread friction vanishes for an instant and the nut ratchets back one thread at a time; preload collapses within tens of cycles. Only three philosophies exist: stop it turning, block it backing off, or lock it permanently. The performance ranking follows general behaviour under ISO 16130 (Junker) testing; actual results vary with size, surface and load - critical joints need their own or third-party vibration tests.
Parameter Comparison Table
| Property | Nylon Insert (DIN985) | All-Metal (DIN980) | Threadlocker |
|---|---|---|---|
| Locking principle | Nylon collar grips stud | Metal deformation grips thread | Adhesive fills thread gap |
| Transverse-vibration resistance | Good | Good | Excellent |
| Removability | 5-10 remakes | Few remakes | Heat-removable / permanent |
| Temperature range | -40 ~ +120°C | 至 300°C+ | 150°C+ 视型号 |
| Relative cost | 低 | 中 | 低 |
| Typical scenario | Vibration / frequent maintenance | Engines / hot piping | Safety parts / maintenance-free |
Selection Conclusion
Decide in three steps: check service temperature first - above 120°C nylon is out; pick all-metal locking or threadlocker for hot equipment. Then ask about disassembly - frequent maintenance takes removable types (nylon insert / double nut); safety and maintenance-free joints take threadlocker as permanent (medium-strength removable grades release around 150-200°C but need re-application; high-strength grades are non-removable by design). Finally weigh budget and space. Spring washers contribute little against transverse vibration and should not be your primary lock; if a joint keeps loosening, verify preload and structural removal of transverse slip first.
FAQ
Change the scheme rather than stack it. A spring washer is mostly axial elasticity, helps little against rotation from transverse slip, and its small bearing face destabilizes friction torque. Where locking matters, use nylon-insert lock nuts, double nuts or serrated flange hardware instead.
All-metal lock nut (DIN980): good transverse-vibration resistance to 300°C+ by local metal deformation, at the cost of few remakes. Nylon inserts age out above 120°C and do not belong in the hot zone.
Medium-strength removable grades release when heated to about 150-200°C, but the cured layer is destroyed - re-apply on reassembly. High-strength permanent grades are non-removable by design. Frequently opened inspection points should use mechanical removable locks.
Run type testing to ISO 16130 (Junker transverse vibration) and rely on your own or third-party data for critical joints - behaviour shifts with size, surface and load, so a generic ranking should not be copied blind.
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