For optimal performance and maximum locking effect, a Schnorr washer is installed with its convex side against the bolt head or nut, and its concave side facing the component material. This specific orientation is crucial to leverage the washer's unique design and prevent bolted joints from loosening under vibration and dynamic loads.
Understanding Schnorr Washers
Schnorr washers, also known as serrated safety washers or conical spring washers, are precision-engineered locking devices designed to maintain tension in bolted joints. Unlike standard flat washers, they feature a conical shape and radial serrations on both surfaces. When tightened, these washers flatten, creating a powerful spring force while their serrations bite into both the fastener and the mating surface, resisting rotation.
The Importance of Correct Orientation
The effectiveness of a Schnorr washer hinges significantly on its correct installation. Installing the washer in the recommended orientation ensures that its conical spring action and serrated grip are maximized. Using the washer "up-side down" can diminish its locking capabilities, potentially leading to reduced preload retention and an increased risk of self-loosening.
Key Principle for Maximum Locking Effect:
The primary goal is to ensure the washer's conical shape can effectively exert its spring force against the tightening fastener while the serrations securely engage.
- Convex Side: This is the outer, domed side of the cone. It should face the underside of the bolt head or the nut.
- Concave Side: This is the inner, bowl-shaped side of the cone. It should face the surface of the component being fastened.
This setup allows the washer to be compressed and flatten against the fastener, providing constant spring tension, while its serrations prevent relative movement between the surfaces.
Practical Installation Guide
Follow these steps for proper Schnorr washer installation:
- Preparation: Ensure the mating surfaces on both the fastener (bolt head or nut) and the component are clean, flat, and free from burrs or excessive coatings.
- Positioning: Place the Schnorr washer over the bolt.
- If installing under a bolt head, orient the washer so its convex side faces the bolt head.
- If installing under a nut, orient the washer so its convex side faces the nut.
- The concave side will naturally face the surface of the part being secured.
- Assembly: Assemble the rest of your bolted joint (e.g., bolt, washer, component, nut).
- Tightening: Torque the fastener to the manufacturer's specified value. As you tighten, the Schnorr washer will flatten, its serrations will embed into both mating surfaces, and the conical spring will generate axial force, locking the joint.
Visual Aid: Schnorr Washer Orientation
| Side | Faces | Purpose |
|---|---|---|
| Convex (Outward Curve) | Bolt Head or Nut | Allows conical spring action to exert force against the fastener, preventing loosening. |
| Concave (Inward Curve) | Component Surface | Ensures serrations securely bite into the material being clamped. |
Why This Orientation Works Best
- Optimal Spring Action: When the convex side faces the fastener, the washer's conical form is optimally positioned to be compressed by the tightening torque. This compression stores potential energy, which is then released as a continuous spring force, counteracting any tendency for the fastener to loosen.
- Secure Serration Engagement: The serrations on both sides of the washer embed into the softer material of the fastener and the component, creating a positive lock that resists rotation. This is particularly effective against vibrations and dynamic loads.
- Preload Retention: By maintaining a consistent clamping force, the Schnorr washer helps to retain the initial preload of the bolted joint, which is critical for joint integrity and preventing fatigue failures.
Common Applications
Schnorr washers are highly effective in applications where vibration, thermal expansion, or dynamic loads might cause standard fasteners to loosen. They are frequently used in:
- Automotive and heavy machinery
- Industrial equipment and robotics
- Construction and infrastructure
- Electrical and electronic assemblies
- Any application requiring high-reliability bolted connections
By adhering to the correct installation orientation, you ensure that these innovative safety washers deliver their intended maximum locking effect, safeguarding your critical assemblies.
