Spring Washer DIN 127 A2 A4 — Why Choose Grade Stainless Steel Anti Loosening Washer for Bolts and Nuts
Spring Washer DIN 127 — How to Prevent Fastener Loosening in Machinery?
Spring washers (also called split lock washers) are a small, often overlooked component that plays a big role in keeping bolted joints secure. This article explains why spring washers matter, how to choose the right grade and size, proper installation tips, and quick inspection checks you can apply on the shop floor.
- Common spec
- Standard: DIN 127 (split lock washer)
- Materials: stainless steel (A2/A4), carbon steel, alloy steel
- Sizes: typical range M2–M20
Why do spring washers matter?
In assemblies that experience vibration or thermal cycling, threaded fasteners can slowly back off due to small relative movements. A spring washer provides a flexible preload and a bite into the mating surface that helps resist rotation. For many applications, this is a simple, low-cost measure that greatly reduces maintenance and unexpected downtime.
How spring washers work — a practical view
The split design gives the washer a slight helical shape. When the nut or head is tightened, the washer compresses and exerts an elastic force against the joint. This maintains friction between the threads and helps the fastener resist loosening. Keep in mind it is a mechanical aid — not a miracle; correct torque, surface condition and material choice remain essential.
When to use a spring washer vs other locking methods
Spring washers are best for medium-duty vibration environments where reworkability and cost matter. Alternatives include nylon-insert lock nuts, nylon patch screws, mechanical lock washers, and chemical threadlockers. Each has pros and cons:
- Spring washer: inexpensive, reusable, good for general machinery.
- Nylon patch screw / nylon insert: built-in locking without extra parts — see our nylon patch screw range for anti-loosening fasteners.
- Chemical threadlocker: strong hold but not ideal when parts must be frequently removed.
Selection: grade, finish and size
Choose material and grade based on environment and load. Stainless steel (A2/A4) is preferred for corrosion resistance; carbon or alloy steel can be used where higher strength and protective plating are acceptable. Match washer outer and inner diameters to the bolt size per DIN recommendations — a correct fit ensures proper spring action and seating.
Installation tips for reliable performance
- Clean mating surfaces — dirt or paint under the washer reduces bite.
- Use the specified torque for the bolt grade and size. Over-tightening flattens the washer and reduces effectiveness.
- Inspect at first maintenance interval — if the washer is deformed or corroded, replace it rather than reuse.
- For critical assemblies, consider combining a spring washer with a secondary locking device (e.g., lock nut) for redundancy.
Inspection & quality checks
Quick checks help avoid failures: confirm correct washer type, check for even compression around the circumference, verify corrosion resistance of the finish, and sample-test torque retention on a production batch. Request batch traceability and material certificates from suppliers where needed.
Buyer’s checklist
When sourcing spring washers, ask for: DIN-based dimensional data, material grade (A2/A4 or specific alloy), finish details (zinc, phosphate, passivation), and test reports. A reliable supplier will provide clear MOQ, lead times and technical sheets — which helps you plan assembly lines and inventory.
Short FAQ (for quick answers)
Q: Can spring washers be reused?
A: They can be reused a few times in non-critical assemblies, but for safety-critical or highly vibratory applications, replacement is recommended.
Q: Do spring washers prevent all loosening?
A: No single method is perfect. Spring washers reduce loosening risk in many cases but combine with proper torque and material choice for best results.