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The Grooved Pin Principle
The fastener incorporates in its design three
longitudinal grooves swaged or formed into a cylinder of material,
which has the effect of increasing its diameter. In the case
of unheaded pins, this may be over part or all of the length
of the pin and may be of a tapered or parallel form. In the
case of Headed pins, the grooves are always parallel and,
with Blind Drive Pin Rivets, the pin is used to expand the
rivet and is retained in the body of the rivet.
In each product, installation of the grooved
pin causes the grooves to compress, this compression produces
outward pressure on the walls of the hole and in so doing
secures location of the pin. Diagram 1 shows compression taking
place as a section through a grooved pin.
When compared with more traditional
taper pins, plain pins, keys or locating pins which rely on
'interference' at one point on the pin and also require a
reamed or precision formed hole, the grooved pin principle
can be seen to represent a significant improvement. Resistance
to withdrawal occurs wherever the grooved diameter is compressed;
it can be over the whole length of the pin instead of just
at one point as with traditional pins. This advantage is represented
in diagram 2.
Why Use Grooved Pins
Simple
Hole Preparation |
- No reaming or threading of the hole prior to installation
is required
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Resistance
to Shock and Vibration |
- Because the pin is held in position under elastic
tension, it cannot easily be dislodged in harsh environments
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Total
Range |
- Standard pin types are available for many applications,
eliminating the need for more labour intensive or
complex fasteners, or custom designed expensive parts
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They
are Reusable |
- When removed from the application, the grooves recover
their form and can be reused many times with only
minimal reduction in pull out performance
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Simple
Installation |
- Providing correct procedures are followed, there
is no need for special installation equipment for
small volumes. Where high production quantities are
anticipated, the pin can easily be fed and does not
require sophisticated installation equipment
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Strength |
- The Tappex Grooved Pin is a solid steel fastener
giving high shear strength and good wear resistance
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Installation Information
Hole
Preparation |
- When drilling the hole for installation of a grooved
pin, a standard twist drill should be used of the
same nominal diameter as the ungrooved pin. Use hole
tolerance H9 for pins under 3mm and H11 for 3mm and
above, although in steel a slightly larger hole will
only marginally affect withdrawal loads. Tappex Grooved
Pins are produced with a minus tolerance on the ungrooved
diameter to allow easy fit.
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Pin
Strength |
- The tensile strength of the pin must be the same
as or higher than the strength of the component material.
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Installation |
- Parallel groove pins require significantly higher
installation forces than tapered groove pins. To eliminate
the chance of any difficulty during installation,
a 60ยบ counter sink should be incorporated into the
hole and the pin should be slightly lubricated prior
to installation. During installation it is important
to ensure correct alignment between the pin and the
hole.
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Installation Forces
These figures give data on average installation forces required
for tapered and parallel grooves. Generally the force to remove
a pin is slightly more than the force required to install
it.
Tapered Grooves - insertion
force in kgs per length of groove
Parallel Grooves - insertion
force per mm of groove
Standard Tolerances
Body Diameter, dome and
length
Tolerance on body diameter
and dome
d1 = Body diameter C = Height of dome L = Body Length
Tolerance on length 'l'
| The Grooved Pin
designs are subject to certain standard tolerances, which
are listed here. Other specified tolerance information
is provided is provided in our literature. |
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1mm - 3mm |
+/- |
0.200 |
over |
3mm - 6mm |
+/- |
0.240 |
over |
6mm - 10mm |
+/- |
0.290 |
over |
10mm - 18mm |
+/- |
0.350 |
over |
18mm - 30mm |
+/- |
0.420 |
over |
30mm - 50mm |
+/- |
0.500 |
over |
50mm - 80mm |
+/- |
0.600 |
Product Identification
The part number is made up of the nominal diameter
and effective length. The example shown here is for Grooved
Pin S8 - third length centre tapering grooves - DIN 1475.
A standard part number assumes a plain steel material. Other
materials should be noted at the time of specifying by quoting
the appropriate material reference.
Material Specifications
Grooved Pins, Headed Grooved Pins
The Tappex Grooved Pin system is manufactured in West Germany,
consequently material specifications relate to DIN standards.
Various options are available and these are given below together
with DIN reference numbers where appropriate and the corresponding
British Standard number where available. Various Standards
of finish are available where applicable If more information
is required, please contact our Technical department.
These Grooved Pins are produced
in Germany by Kerb-Konus-Gesellschaft and
Tappex Thread Inserts Ltd. are their Sole Distributor in the
U.K. and Eire.
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profile
sample/quotation