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Unit 3 Durham Lane
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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SERVICES & SUPPORT
Clinch Nuts
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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
Test panel held
firmly in vice.
Applied torque
from dial measuring
torque wrench.
Flat washer
2 pitch min.
Bolt (Grade 5 min.) Ensure
full thread engagement
(min. 6 threads
recommended).
Torque-out testing of Self-Clinching Standoffs 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 standoff turning in the panel or cam-out.
Pull-through test for Self-Clinching Standoffs 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 hexagon head and inserted into the test rig lower link. A hardened bushing should be inserted into the test rig
upper link and a bolt screwed down into the standoff. 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 threads.
Pull-through values pertain only to the amount of force required to pull the hexagon head through the panel or for
head failure.
Tensile testing rig
upper link
Tensile testing Rig
lower link
Hardened bushing
Hardened bushing.
Applied Load.
Bolt (Grade 5 min.)
Ensure full thread
engagement (min. 6
threads recommended).
Performance
Thread
size
Max. nut
tightening
Torque (Nm)
M3
0.33
Installation
(kN)
Torque-out
(Nm)
Pushout
(N)
Aluminium
Test sheet
material
Pull-thru
(N)
Steel
0.44
0.55
Standoff
material
Aluminium
Steel
300 Stainless
Steel
300 Stainless
400 Stainless
Stainless
5.0
5.0
5.0
10.0
10.0
25.0
0.55
0.55
0.44
725
725
725
1000
1000
1500
1.25
1.25
1.25
2.25
2.25
2.35
750
1250
1000
1475
1200
2650
5.4M3
0.33
Aluminium
Steel
0.44
0.55
Stainless
7.5
7.5
7.5
15.0
15.0
43.0
0.55
0.55
0.44
1350
1350
1350
1860
1860
2900
2.85
2.85
2.85
3.95
3.95
3.10
825
1100
830
1700
1350
3050
M3.5
0.55
Aluminium
Steel
0.73
0.91
Stainless
7.5
7.5
7.5
15.0
15.0
43.0
0.91
0.91
0.73
1350
1350
1350
1860
1860
2900
2.85
2.85
2.85
4.00
4.00
3.10
825
1100
850
1700
1350
3050
M4
1.20
Aluminium
Steel
1.60
2.00
Stainless
10.5
10.5
10.5
18.0
18.0
47.0
2.00
2.00
1.60
1800
1800
1800
2500
2500
4000
5.10
5.10
5.10
8.50
8.50
8.90
1550
2600
2100
3100
2500
6400
M5
2.16
Aluminium
Steel
2.88
3.60
Stainless
10.5
10.5
10.5
18.0
18.0
47.0
3.60
3.60
2.88
1800
1800
1800
2500
2500
4000
5.10
5.10
5.10
8.50
8.50
8.90
1550
2600
2100
3100
2500
6400
Aluminium
Steel
300 Stainless
Steel
300 Stainless
400 Stainless
Aluminium
Steel
300 Stainless
Steel
300 Stainless
400 Stainless
Aluminium
Steel
300 Stainless
Steel
300 Stainless
400 Stainless
Aluminium
Steel
300 Stainless
Steel
300 Stainless
400 Stainless
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.
With the panel held level, apply a parallel squeezing force until the hexagon 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.
A
Length of standoff
+6.35mm min.
Anvil Dimensions
A
+0.08
5.49
4.30
7.22
Thread code or
Thru-hole dia.
5.4M3|M3.5|63.1|63.6
M2.5|M3|43.1
M4|M5|83.6|84.1|85.1
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 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.
400 Series Stainless Steel (400) parts are suitable for installation in ductile panels with a
maximum recommended hardness of 88 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 or Thru-Hole code)-(Length)-(Material/Finish code)
For example:
NSO-M3-10-A2 (Thru-threaded standoff-M3 thread-10mm long-stainless steel)
NSO-5.4M3-8-AL (Thru-threaded standoff-M3 thread (larger body)-8mm long-aluminium)
NBSO-M4-12-ZI (Blind-threaded standoff-M4 thread-12mm long-electro zinc plated steel)
NSO-43.1-6-A2 (Clearance-hole standoff-3.1mm dia.-6mm long-stainless steel)
Info
Self-Clinching Standoffs provide strong captivated reusable female threads in a spacer format in panels as thin as
1.0mm.
Utilising a hexagon head and a special proven 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.
Self-Clinching Standoffs are available in a range of thread sizes and lengths, in through-threaded, blind-threaded
and clearance-hole styles. Manufactured from electro zinc plated carbon steel, 300 and 400 series stainless steel,
aluminium and are suitable for installation in ductile panels with a recommended maximum hardness of 80 HRB
for steel parts, 70 HRB for 300 series stainless steel parts, 88 HRB for 400 series stainless steel parts and 50 HRB for
aluminium parts.
Dimensional Data
Self-Clinching fastener
Do’s & Don’ts
Self-Clinching fastener
problem solving guides
Downloadable
Data Sheet
Back
Installation
Type NSO & NBSO
SELF-CLINCHING
STANDOFFS
Hardened bushing with
sufficient wall thickness
to withstand applied
compression load.
Head Dia.
+ 1.6mm
Test panel.
Applied Load from
compression gauge.
Compression rig base.
Push-out testing of Self-Clinching Standoffs 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 standoff during testing. The bushing bore
must be centred on the hexagon head of the standoff.