Curved Split Lockwasher
Our DIN 128 A curved split lock washers are split metal rings formed into a gentle curve rather than a helical coil. As the fastener is tightened, the curved profile compresses flat and stores spring tension between the bolt head and substrate, resisting loosening from light vibration without the gouging action of toothed washers — a good fit for soft or finished surfaces, electronics, and lightweight fixtures.
Disclaimer: Product images are representative. Product specifications and descriptions govern the item you will receive.
Curved Split Lockwasher — Metric Sizes
What Is a Curved Split Lockwasher?
A curved split lock washer is a single-turn metal ring, split at one point and pressed into a shallow curved (bowed) shape rather than a flat helix. Manufactured to DIN 128 Form A, it functions purely as a spring: when the fastener is tightened, the washer flattens and stores elastic energy, which it releases as a constant clamping preload that resists loosening from light vibration and thermal movement. Because the split ends are not bent or chiseled to grip, and the surfaces are smooth, curved split washers leave finished and plated surfaces undamaged — unlike toothed or serrated lock washers. DIN 128 A is commonly specified as a modern replacement for the older DIN 127 helical split washer in light-duty assemblies, and its non-directional curve allows it to be tightened in either rotational direction.
Key Features and Benefits
- Surface-Friendly Locking: A smooth curved profile stores spring tension without biting into the bolt head or work surface.
- Non-Directional Design: Works equally well with right-hand and left-hand threaded fasteners.
- Compact, Low-Mass Construction: Adds negligible weight or stack height to small assemblies.
- Vibration Resistance: More resistant to thrust-induced loosening than a standard helical split washer of similar size.
- Modern Replacement: Frequently specified in place of DIN 127 in new designs.
Materials and Finishes
- Spring Steel, Zinc Plated: Standard option for general-purpose light assemblies.
- Stainless Steel A2: Corrosion resistance for electronics, instruments, and indoor or outdoor enclosures.
- Stainless Steel A4: Marine and chemical-resistant applications.
Standards Compliance
- DIN 128 A — Curved (split) spring washers
- DIN 137 A — Non-split curved spring washer (reference)
- DIN 127 — Standard helical split spring lock washer (reference)
Size Range and Availability
Available in M2 through M24 in metric coarse thread, in zinc-plated spring steel and A2/A4 stainless steel.
Frequently Asked Questions (FAQs)
1. What is a curved split lockwasher used for?
Curved split lock washers are used on light-duty assemblies where a gentle, surface-friendly spring lock is needed — electronics enclosures, instruments, lightweight brackets, and finished or plated surfaces that shouldn’t be marred.
2. What is the difference between a curved split washer (DIN 128 A) and a curved washer (DIN 137 A)?
DIN 128 A is a split ring formed into a curve, combining the spring action of both the split and the curve. DIN 137 A is a solid, uninterrupted ring that relies purely on its curved shape for spring force. Both are light-duty washers, with DIN 128 A often specified as the improved replacement for older split designs.
3. How is this different from a standard split lock washer (DIN 127)?
DIN 127 is a helical coil with cut ends that can dig in slightly. DIN 128 A is curved rather than helical, with smoother, non-directional action, and is generally recommended as the modern replacement for DIN 127 in new designs.
4. Will it damage painted or plated surfaces?
No. The curved split washer has no teeth and relies entirely on spring tension, so it is a good choice where surface damage must be avoided.
5. Can it be used with left-hand threaded fasteners?
Yes. The curved design is non-directional and works with both right-hand and left-hand threads.
6. What materials are available?
Zinc-plated spring steel, plus A2 and A4 stainless steel for corrosion resistance.
7. Is it reusable?
Light reuse is generally acceptable if the spring hasn’t fatigued or flattened permanently; for critical or frequently serviced joints, install a new washer.
8. What sizes do you stock?
M2 through M24 in metric coarse thread.
9. Should it be combined with a flat washer?
On soft or thin materials, pairing a curved split washer with a flat washer beneath it helps spread the load and prevents the spring washer from marking the surface.
10. What standard governs this washer?
Curved split lock washers are manufactured to DIN 128, Form A.
