Technical Data
1. Difference in hardness: HHEICO > HMaterial
- The surface hardness of HEICO-LOCK® Wedge Lock Washers is greater than that of structural grade and high tensile bolts (e.g. strength classes: 8.8, 10.9,12.9)
- Radial teeth/ridges on the outside of the washers grip into and seat the mating surface in the tightening process
Material information
| Material | Hardness | Corrosion resistance |
|---|---|---|
| Steel (1.1191 / C45E) (through-hardened, zinc flake coated) |
485 ±25 HV0.3 | Min. 600h in neutral salt spray test (acc. to ISO 9227) |
| Stainless Steel A4 (1.4404 / 316L) (surface hardened) |
> 520 HV0.1 |
Min. 1.200h in neutral salt spray test (acc. to ISO 9227) |
2. Difference in angles: α > β
- The wedge angle (α) between the HEICO-LOCK® Wedge Lock Washers is greater than the pitch (β) of the bolt thread
- This angle means the expansion in thickness of the HEICO-LOCK® Wedge Lock Washers is greater than the possible longitudinal movement of the bolt along the thread
3. Difference in friction: μa > μi
- The wedge-shaped surfaces have a considerably lower friction coefficient μi than the toothed outside of the washers (friction coefficient μa)
- Loosening caused by dynamic stresses causes movement between the two washers in the region of the wedged surfaces
4. Difference in preload: Fdyn > Fstat
- An expansion in thickness of the HEICO-LOCK® Wedge Lock Washers as a result of loosening leads to an increase in the clamping force
- This causes an increase in the preload compared to when in a static state and thus causes the bolt to self-lock
5. HEICO-LOCK® Wedge Lock Washers with a large outside diameter
Large O.D. HEICO-LOCK® Wedge Lock Washers are recommended for use on large/long holes (for example with flange nuts or screws), painted surfaces or soft materials, for example aluminum.