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Hardness Conversion Table
 
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Typical Assemblies

Technical Data 

1. Differences in hardness HHEICO > HMaterial

  • The surface hardness of the Heico-Lock® wedge lock washers is greater than that of structural grade and high tensile bolts (8.8, 10.9 & 12.9) and should always exceed the hardness of the mating surface. 

  • Radial teeth on the outside of the washers grip into and seat the mating surface in the tightening process.

Heico-Lock® Hardness Table

Material

Sizes

Zinc Laminate Finish

    Non Coated

Standard Steel
(through hardened)

H-HLS-3 to H-HLS-42 
H-HLB-3 to H-HLB-42

485 ±25 HV0.5

 

316L Stainless Steel
(surface hardened)

H-HLS-3 to H-HLS-42S 
H-HLB-3 to H-HLB-42
S

 

>520 HV0.05












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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.


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3. 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.
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4. 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.
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5. HEICO-LOCK® with 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 aluminium.
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