ISO 4579-2021 pdf free download – Aerospace — Drives, internal, TORX PARALOBE drive — Geometrical definition, gaging and technical requirements.
This international standard specifies basic dimensions, characteristics and engineering requirementsfor TORXR PARALOBERrecesses in aerospace fasteners.
2Normative references
The following documents are referred to in the text in such a way that some or all of their contentconstitutes requirements of this document. For dated references,only the edition cited applies. Forundated references, the latest edition of the referenced document (including any amendments) applies.ISO4580,Aerospace —Internal drive,TORX@PARALOBERdriver bit —Geometrical definition, gaging andtechnical requirements
NASM1312-25,Fastener Test Methods – Method 25 – Driving Recess Torque Quality Conformance Test
3Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:-ISO online browsing platform: available at https://www.iso.org/obp
—IEC Electropedia: available at http://www.electropedia.org/
3.1 Recess
Geometry in a fastener that allows attaching a tool in order to induce a torque to enable tightening anduntightening of a fastener
3.2 Driver bit
Tool to induce a torque into a fastener’s recess
3.3 Configuration
Shape and geometry of the cross section of a recess or external drive
3.4 Optimum recess torque
The optimum torque in a recess is reached when the recess is able to transfer the ultimate torque of thedriver bit
4Basic fastener recess configuration
The basic recess configuration shall be in accordance with Figure 1.
5 Recess inspection
5.1 Gaging equipment
The recess is inspected with a penetration gage (see Figure 2).
5.2 Gaging procedure Using the appropriate size gage (see Table 2), check the zero adjustment against a known flat surface. Insert the gage element into the recess and firmly push the top of the recess against the bottom of the gage body. Measure and record the gage depth. The reading shall be within acceptable limits per application fastener standard.
6 Fastener recess torque test
6.1 Fixture The test fixture shall be capable of maintaining alignment with the fastener axis, ensuring non- rotation of the fastener, applying a specified end load and applying torque in both clockwise and anti- clockwise directions. The fixture shall not resist any tendency of the driver bit to cam out of the recess during the test.
6.2Torque wrench/torsion machine
Hand torque wrench shall conform to applicable requirements.
Torsion machines or other power tools shall conform to applicable requirements.6.3 Driver bit
The driver bit shall be appropriate for the recess being tested and shall be in accordance with therequirements of ISO 4580.
6.4Test specimen
The shank of the fastener or fastener head may be modified to ensure non-rotation during testing.Therecess has to be gaged after fastener modification.
6.5Fastener recess torque test procedurea)Place fastener in a suitable test fixture.
b) Mate the driver bit with the recess of the fastener, ensuring that the bit is free to move in or out of the
recess and the bit axis is constrained within 1 degree of angular alignment with the fastener axis.c)
Apply an end load as specified in NASM1312-25 or other applicable document. The total end loadshall be effective at bit/fastener juncture.
d) With the bit mated to the recess and the end load applied (but no torque applied),zero the torque
measuring device if applicable.
e) Apply the torque slowly in the installation direction at a smooth, continuous rate until the minimum
torque, as specified in the applicable fastener standard, has been reached.The optimum recesstorque values can be found inTable 3.
fRecord the applied torque and mode of failure, if any.g) Disengage the fastener and driver.
h) Repeat 6.5 a) through 6.5 g), applying torque in the removal direction, using the same driver bit
and fastener.
6.6Fastener recess torque values
The torque values given in Table 3 represent the minimum torsional strength values of the driverbit according to ISo 4580.The torque values that the drive system in the fastener can transfer aredependent on drive size, material and penetration depth. The deeper the recess the higher the drivesystem strength.However head and fastener geometry have to be considered to select the appropriatepenetration depth.Refer to specific fastener standards for specific torque test values.ISO 4579 pdf download.