When designing joints with washers, it is important to understand and use the correct washer for the job. Below are a few tips for making a good selection:
1. When using flat washers, match washer hardness with bolt and/or nut hardness to avoid joint settling.
- 140 HV ≤ 8
- 200 HV ≤ 8
- 300 HV ≤ 9
2. Split lock washers are not intended for use with hardened bolts/nuts, only with property class ≤ 8.
3. Toothed lock washers are designed to permit electric current flow between components, and do not provide much of a locking feature. They are also only used for low property class ≤ 8.
4. Specialty washers exist for high strength joints, for example:
- Rip-Lok – designed for property class 8.8
- Conical spring washer with serrations on top
- Schnorr washer – designed for property class 10.9
- Small OD conical spring washer with serrations on both sides