ISO 23886-2021 pdf free download – Aerospace — Collar, threaded, self- locking — Test method for torque and preload.
This document describes torque and preload test method for threaded collars.This test method is usedto measure the locking torque, breakaway torque, torque off and preload of threaded collars.
2Normative references
There are no normative references in this document.
3Terms and definitions
For the purposes of this document, the following terms and definitions apply.
IS0 and IEC maintain terminological databases for use in standardization at the following addresses:- ISO online browsing platform: available at https:.//www.org/obp
—IEC Electropedia: available at https://www.electropedia.org/
3.1
locking torque
highest torque value obtained in the installation direction prior to contact with the bearing surface3.2
breakaway torque
torque required to start threaded collar rotation from its installed position
Note 1 to entry:The breakaway torque shall be measured after twisting off the hex portion and after removal ofthe preload.
Note 2 to entry: The breakaway torque is for seated breakaway test only.3.3
test bolt
bolt to be used in conjunction with the collar during the test
4 General requirements
4.1Test apparatus
A torque tension test bench, torsion machine or the equivalent precision machine shall be used for thetest, which shall have been calibrated within a period of 12 months prior to the test date.
4.2Test bolt
Test bolt shall be in accordance with product specification.
4.3Test accessories
The material of the collar bearing surface (see Figure A.2, item 8) shall be alloy steel; the roughness ofthe interface contacting with the collar shall be between Ra = 0,4 um and Ra = 0,8 um. The hardnessshall be 50 HRC to 60 HRC.
5Detail requirements
5.1Test procedures
a) Install the test bolt on the torsion machine; install the threaded collar finger tight against the locking element; install the threaded collar hex head into the socket adapted to the machine drivemechanism. See Figure 1.Measure the distance between the end surface of the bolt and threadedcollar; then calculate the cycling number.
b) Rotate the threaded collar at the rate of (10 ± r/min. Continue applying the torque until the threaded collar seats (the hex portion of threaded collar twists off), as shown in Figure 2. ISO 23886 pdf downoad.