Lock washers are essential to military-grade fastener systems due to their ability to resist vibration, shock, and rotational loosening. Whether used in aircraft, ground vehicles, or naval platforms, they help protect critical assemblies against failure in harsh conditions.
What Are Lock Washers?
Lock washers are specially designed washers—such as split, tooth, or spring types—placed under bolt heads or nuts to prevent back-out and maintain clamp load over time. Unlike plain washers, they resist rotation by increasing friction or providing spring action:
- Split lock washers create an axial spring tension that keeps the joint tight.
- Tooth lock washers (internal or external) bite into the surface and fastener, resisting loosening through serration.
- Spring/Belleville lock washers offer compressive elasticity to maintain preload under vibration.
Why They Matter in Military Applications
Military platforms are often subjected to extreme vibration, shock, and dynamic loading. These forces can loosen fasteners over time—posing serious safety risks. Lock washers provide dynamic resistance:
- Vibration resistance maintains clamp force during constant operational vibrations in aircraft and armored vehicles.
- Shock and impact resistance disperses sudden forces from explosive or rough-terrain events, preserving structural integrity.
Innovation in Lock Washer Design
Military fastener technology is continuing to evolve:
- Smart lock washers with embedded sensors now monitor tension in real time.
- Composite lock washers, which combine metal strength and lightweight properties, are being explored for naval and aerospace applications.
Why It Matters
Lock washers play a small but crucial role in mission reliability. Inadequate locking leads to fastener loosening, with potential consequences from system misalignment to total equipment failure. Partnering with a DFARS-compliant supplier like Metric Bolt ensures lock washers meet military standards and are traceable—protecting mission integrity.
| Washer Type | Function | Key Benefit | Material/Finish | Military Spec |
|---|---|---|---|---|
| Split (Helical) | Axial spring preload | Simple & lightweight vibration resistance | Steel, zinc/CAD plated, SS | NASM 35338, MS 35338 |
| Tooth (Internal/External) | Serrated locking bite | High torque resistance, especially on soft surfaces | Carbon/SS, zinc plated | NASM 35333, MS 35333 |
| Belleville (Conical) | Compression spring action | Maintains preload under cyclic high-loads | Hardened steel, SS | MS 35338 L, NASM 1676 |
