Universal Fastening System – 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.

Groove compression

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.

Simple, Reusable, Resistant to Shock and Vibration

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?

Installation Information

Installation Forces

These figures give data on the 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’

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 center tapering grooves – DIN 1475. A standard part number assumes a plain steel material. Other materials should be noted at the time of specification by quoting the appropriate material reference.

Material Specifications
Grooved Pins, Headed Grooved Pins
The Tappex Grooved Pin system is manufactured in 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  Sales office.

Grooved Pins

Headed Grooved Pins

These Grooved Pins are produced in Germany by Kerb-Konus-Gesellschaft and Tappex Thread Inserts Ltd. are their Sole Technical Distributor in the U.K. and Eire.