EN ISO 2320:2015

European foreword
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols
5 Thread
6 Lubrication
7 Mechanical properties of prevailing torque nuts
8 Functional requirements for prevailing torque properties
9 Test method
Annex A (normative) - Temperature influence on prevailing
        torques of nuts with nonmetallic insert
Annex B (informative) - Principles for the evaluation of the
        total coefficient of friction, [mu]tot
Annex C (informative) - Test clamp force and prevailing
        torques for prevailing torque nuts M3 and M4 in
        property classes 8 and 10
Bibliography

ISO 2320:2015 specifies the functional properties for prevailing torque steel nuts when tested at an ambient temperature range of +10 °C to +35 °C. It includes a combined test method to determine the prevailing torque properties and the torque/clamp force properties at the same time.It applies to prevailing torque all metal type nuts and prevailing torque non-metallic insert type nuts:- with triangular ISO thread in accordance with ISO 68‑1;- with diameter/pitch combination in accordance with ISO 261 and ISO 262;- with coarse pitch thread M5 to M39 or with fine pitch thread M8 × 1 to M39 × 3;- with thread tolerances in accordance with ISO 965-2;- with mechanical properties in accordance with ISO 898‑2;Prevailing torque values specified in this standard are based on laboratory test conditions.NOTE 1 Actual prevailing torques in practical application can vary.NOTE 2 All metal type nuts conforming to the requirements of this International Standard are used in applications ranging from −50 °C to +150 °C.NOTE 3 Non-metallic insert type nuts conforming to the requirements of this International Standard are used in applications ranging from −50 °C to +120 °C.WARNING ? Temperatures outside the ambient temperature range can influence the functional properties (torque/clamp force and prevailing torque properties), see Annex A.