PREVAILING TORQUE VALUES OF METRIC LOCK NUTS


Prevailing Torque Values of Lock Nuts calculator was developed to show prevailing-on torque and prevailing-off torque values of metric lock nuts. This page has been developed according to ISO 2320 : 2008 "Prevailing torque type steel nuts - Mechanical and performance properties" standard.

Some important notes from ISO 2320 standard:

- ISO 2320 specifies performance parameters of lock nuts when tested at an ambient temperature range of 10 °C to 35 °C.

- ISO 2320 applies to prevailing torque all metal type nuts (lock nut with metal insert) and prevailing torque non-metallic insert (lock nut with nylon insert) type nuts

- ISO 2320 applies to lock nuts with metal inserts within the temperature range of −50 °C to +150 °C.

- ISO 2320 applies to lock nuts with nylon inserts within the temperature range of −50 °C to +120 °C.

- ISO 2320 applies to nominal thread diameters up to and including M39 with triangular ISO thread and mechanical properties according to ISO 898-2.

Calculator:

INPUT PARAMETERS
Metric Thread
Property Class

 


RESULTS
Parameter Symbol Value Unit
Designation -- --- ---
Property Class - ---
Thread Series -- ---
Maximum Prevailing-on torque (1st installation)
(Lock nut with metal insert)
TFv,max --- N*m
Maximum Prevailing-on torque (1st installation)
(Lock nut with nylon insert)
---
Minimum Prevailing-off torque (1st removal) TFd,min ---
Minimum Prevailing-off torque (5th removal) ---


Note 1: Prevailing torque performance decreases as number of reuses; the user should take into account the effects of the reduced performance before any reuse.
Note 2: Off torque values given above are required values according to ISO 2320 under laboratory acceptance test conditions. Performance for lock nuts may vary in normal use.

Definitions:

Alloy Steel: A ferrous (or iron-based) alloy that contains appreciable concentrations of alloying elements (other than C and residual amounts of Mn, Si, S and P). These alloying elements are usually added to improve mechanical and corrosion resistance properties.

Prevailing-On torque Torque to rotate the nut on its mating externally threaded component with no clamp force

Prevailing-Off Torque: Torque to rotate after backing off the nut until the removal of the clamp force in the externally threaded component.

Prevailing torque type nut: Nut which is not free-running on a mating thread and has a resistance to rotation independent of clamping or compression forces.

Supplements:



Link Usage
Metric Thread Size and Tolerance Calculator Calculates basic major, minor and pitch diameters of the metric external (bolt) thread and internal (nut) thread according to ISO 724:1993 standard. In addition to basic size calculations, tolerance calculations of different tolerance classes can be done according to ISO 965-1:1998 and ISO 965-2:1998 standards.
Nut Grades, Identification Markings and Strength (Metric) Shows proof strength and Vickers and Brinell hardness values of metric nuts made of carbon steel and alloy steel.

Reference:
  • ISO 2320:2008 – Prevailing torque type steel nuts – Mechanical and performance properties
  • DIN EN ISO 2320:2009-03 – Prevailing torque type steel nuts – Mechanical and performance properties