Best Lock Washers
Lock washers resist loosening under vibration — but not all of them actually work. Pick the type for the joint, not just the cheapest ring in the bin.
What to Look For
- Type: split (helical) for general anti-loosen, tooth for electrical grounding and soft surfaces, Belleville for controlled preload.
- Material: stainless for outdoors, plain steel for dry indoor use.
- Fit: the washer must match the bolt or screw size exactly.
- Serration: internal teeth bite the screw head; external teeth bite the panel.
Top Picks
1. Stainless split lock washer assortment Best overall
The everyday choice for keeping general bolted joints tight, in a full range of sizes.
Check price on Amazon →2. External tooth lock washer kit For grounding
Teeth dig into the mating surface for electrical continuity and anti-rotation on terminals.
Check price on Amazon →3. Belleville disc spring washers For heavy preload
Hold a near-constant clamp force under heat cycling and vibration where split washers flatten.
Check price on Amazon →What to Avoid
Avoid
- Reusing a flattened split washer — once it is flat, it is not locking anything.
- Lock washers on high-strength structural bolts — proper torque is what holds the joint.
- Oversized washers that cock the fastener.
Bottom line: Stainless split washers cover most general work; tooth washers for grounding and anti-rotation; Bellevilles where the clamp load must stay controlled.
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