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Armthorpe
Doncaster
South Yorkshire DN3 3FE
England
+44 (0)1302 836010
+44 (0)1302 831555
sales@npfasteners.com
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© Northern Precision Ltd.
NORTHERN PRECISION LTD
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Company number 3275391
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GB 684 1384 17
NORTHERN PRECISION LTD
Specialist Fasteners
for Sheet Metal
+44 (0) 1302 836010
+44 (0) 1302 831555
Tel:
Fax:
sales@npfasteners.com
Quality
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Self-Clinching Fasteners
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development
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testing
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SERVICES & SUPPORT
Clinch Nuts
Flush Nuts
Blind Nuts
Miniature Nuts
Nyloc Nuts
Locking Nuts
Floating Nuts
Flush Head Studs
Flush Head Studs for
Stainless Steel
Reduced Flush Head Studs
Thin Panel Non-Flush Studs
High Strength Studs
Thin Panel High Strength
Studs
Flush Head Pins
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Panel Fasteners
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Low-Profile Panel Fasteners
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Self-Clinching fastener
Do’s and Don’ts
Self-Clinching fastener
problem solving guides
Self-Clinch in harder panels
Testing Method
Hardened bush.
A minimum of 6 fully
engaged threads is
recommended on
both sides.
Test panel held
firmly in vice.
Applied torque
from dial measuring
torque wrench.
Minimum grade 5
bolt (grade 8 for
NHTS & NHFE
fasteners).
Torque-out testing of Self-Clinching Flush Head Studs should
be performed by the gradual application of torque as shown
while the test panel is securely held in a vice. The bolt must be
of a sufficient grade to resist thread stripping.
Torque must be gradually applied until failure is observed and
a maximum applied torque reading is recorded. Failure mode
is the stud turning in the panel, cam-out, or dependent on
stud type/size, thread failure.
Pull-through test for Self-Clinching Flush Head Studs should be performed by the gradual application of an axial load
as shown.
A hardened bushing with a through-hole 0.5mm greater than the diameter of the thread should be centred over the
stud and inserted into the test rig lower link. A hardened threaded bushing should be inserted into the test rig upper
link and screwed down onto the stud. An axial load is then gradually applied on a tensile testing machine to separate
the links until a failure point is reached.
Please note that the pull-through values obtained during this test do not indicate the axial strength of the stud threads.
Pull-through values pertain only to the amount of force required to pull the stud through the panel.
Tensile testing rig
upper link
Tensile testing rig
lower link
Hardened bushing
Hardened threaded bushing.
A minimum of 6 fully engaged
threads is recommended.
Applied Load.
Performance
Thread
size
Max. nut
tightening
Torque (Nm)
M2.5
0.42
Fastener
Type
NFH (ZI)
NFH (A2)
NFH (AL)
Installation
(kN)
Torque-out
(Nm)
Pushout
(N)
Aluminium
Test sheet
material
9.0
9.5
-
11.0
Pull-thru
(N)
460
460
-
0
0.9
0.8
-
0
2610
1830
-
2790
NFH (ZI)
NFH (A2)
Steel
12.0
0
0
1820
-
0.42
M3
0.75
NFH (ZI)
NFH (A2)
NFH (AL)
Aluminium
12.5
12.5
10.5
14.5
610
600
580
820
1.7
1.6
0.5
1.7
3150
2570
1500
3840
NFH (ZI)
NFH (A2)
Steel
14.5
810
1.5
2440
0.44
0.75
M3.5
1.20
NFH (ZI)
NFH (A2)
NFH (AL)
Aluminium
15.5
15.5
-
22.1
800
790
-
1340
1.7
1.7
-
2.9
3790
3440
-
3780
NFH (ZI)
NFH (A2)
Steel
22.4
1335
2.2
3440
-
1.20
M4
1.75
NFH (ZI)
NFH (A2)
NFH (AL)
Aluminium
19.9
22.4
14.5
28.5
970
970
780
1780
2.9
2.9
1.3
4.2
4450
4170
2000
5660
NFH (ZI)
NFH (A2)
Steel
26.9
1750
3.0
4770
1.02
1.75
M5
3.75
NFH (ZI)
NFH (A2)
NFH (AL)
Aluminium
24.3
24.4
15.0
33.8
1080
1075
890
2050
3.6
3.6
2.6
6.6
5170
4760
2500
6280
NFH (ZI)
NFH (A2)
Steel
33.5
2040
6.3
6010
2.10
3.75
M6
5.95
NFH (ZI)
NFH (A2)
NFH (AL)
Aluminium
29.9
28.8
24.5
44.6
1670
1660
1500
2560
7.4
7.3
5.3
11.5
10100
9100
4500
11400
NFH (ZI)
NFH (A2)
Steel
44.3
2560
10.0
10600
3.54
5.95
M8
14.50
NFH (ZI)
NFH (A2)
NFH (AL)
Aluminium
29.7
29.7
-
45.0
1910
1900
-
2900
11.4
11.3
-
19.8
10500
9500
-
15400
NFH (ZI)
NFH (A2)
Steel
49.0
2870
17.6
13600
-
14.50
- No data available at this time.
All performance figures are averages obtained over a range of installations and should be used as an indicator
only. Panel material, hole preparation, installation tooling and method can affect part performance. We always
recommend that you carry out your own tests in the actual application. Please call our sales team and we will be
happy to provide you with samples as well as offering technical assistance.
First punch or drill the correct size hole. Do not deburr or chamfer
the hole prior to installation as this will remove material required
during the clinching process. It is preferable to install the fastener
from the punch side of the panel.
Place the fastener in the prepared hole in the panel and then locate
the fastener in the anvil, ensuring that you are using the appropriate anvil type for the panel thickness like in
the diagram above.
With the panel held level, apply a parallel squeezing force until the head is installed flush to the panel surface.
Do not over squeeze the fastener into the panel as this will result in panel deformation.
When installing Self-Clinching fasteners, please pay attention to the minimum hole centreline to edge and
parent material hardness limitations.
Anvil Dimensions
B
+0.1
3.6
3.1
4.1
4.6
A
+0.08
3.03
2.53
3.53
4.03
Thread size
M3
M2.5
M3.5
M4
6.6
5.6
8.6
6.03
5.03
8.03
M6
M5
M8
A
Length of stud
+3.2mm min.
A
Length of stud
+3.2mm min.
90°
B
Countersunk hole style anvil for
1.50mm or less panel thickness
for thread sizes M2.5 - M5 and
2.40mm or less panel thickness
for thread sizes M6 - M8.
Straight thru hole style anvil for
1.51mm minimum panel
thickness for thread sizes M2.5 -
M5 and 2.41mm minimum panel
thickness for thread sizes M6 -
M8.
Do not remove any extra material or
chamfer the hole as this could result in
improper installation or reduced
performance.
HRB (ROCKWELL HARDNESS B SCALE)
Ensure that you are installing into a
panel that is ductile and at or below the
published maximum recommended
hardness for the fastener.
Ensure that attention is paid to the
minimum hole centreline to edge
dimension for each fastener. Installing
too close to an edge or bend could result
in improper installation or reduced
performance. Minimum centreline to
edge dimensions shown for each
fastener apply to one edge only. If this
distance is applied on multiple sides
there will be significant panel distortion
unless the panel edges are supported
during installation.
Material & Finish
Electro Zinc Plated Carbon Steel (ZI) parts are suitable for installation in ductile panels
with a maximum recommended hardness of 80 HRB.
300 Series Stainless Steel (A2) parts are suitable for installation in ductile panels with a
maximum recommended hardness of 70 HRB.
Aluminium (AL) parts are suitable for installation in ductile panels with a maximum
recommended hardness of 50 HRB.
Part Number Examples
Part number is made up as follows:
(Type)-(Thread)-(Length)-(Material/Finish code)
For example:
NFH-M3-10-ZI (Flush Head Stud-M3-10mm long-electro zinc plated carbon steel)
NFH-M4-12-A2 (Flush Head Stud-M4-12mm long-stainless steel)
NFH-M6-20-AL (Flush Head Stud-M6-20mm long-aluminium)
Use part designation NFHD to specify a dog-point thread lead-in (special order).
Info
Self-Clinching Flush Head Studs provide strong reusable captivated male threads in thin panels.
Utilising a special proven castellated clinch feature, this fastener has excellent torque-out, pull-through and push-
out characteristics whilst providing a flush finish on the underside of the panel, meaning that minimal surface
finishing is required after installation.
Like all self clinching fasteners they are installed using a parallel squeezing action, so require access to both sides of
the panel.
Flush Head Studs are available in a range of thread sizes and lengths, manufactured from electro zinc plated steel,
300 series stainless steel and aluminium and are suitable for installation in ductile steel and aluminium panels with
a recommended maximum hardness of 80 HRB for steel parts, 70 HRB for 300 series stainless steel parts and 50
HRB for aluminium parts.
Flush Head Studs can also be supplied with a dog-point thread lead-in to aid component assembly.
Dimensional Data
Self-Clinching fastener
Do’s & Don’ts
Self-Clinching fastener
problem solving guides
Downloadable
Data Sheet
Back
Installation
Type NFH
SELF-CLINCHING
FLUSH HEAD STUDS
Hardened bushing with
sufficient wall thickness
to withstand applied
compression load.
Head Dia.
+ 1.6mm
Test panel.
Compression rig base.
Push-out testing of Self-Clinching Flush Head Studs should be
performed by the gradual application of a load as shown
above.
Bushing height should be sufficient to allow free downward
movement of the stud during testing. The bushing bore must
be centred on the head of the stud.
Torque-through testing of Self-Clinching Flush Head Studs should be performed by the gradual application of torque as
shown while the test panel is securely held in a vice. The hex nut must be of sufficient grade to resist thread stripping.
Torque must be gradually applied until failure is observed. Failure mode may vary depending on fastener type, size, length
and the properties of the panel the part is installed into. The fastener may actually fracture instead of the head pulling
through the panel.
Please note that the torque-through values obtained during this test do not indicate the axial strength of the stud threads,
the allowable nut tightening torque or the design loading of the assembled component. Torque-through values pertain only
to the amount of torque required to pull the stud through the panel.
Major Thread
Dia. + 0.08mm
Nominal Major Thread
Dia. + 0.5mm
At Least 2 x minimum
recommended panel
thickness for part.
Axial pull-through (kN) load can be calculated by dividing the torque result (Nm) by (0.2 x major dia. of thread).
Hardened Hexagon Nut
Hardened counter-bored
bushing.
Test panel held
securely in vice.
