Coiled Spring Pins

Featured Product from SPIROL

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Coiled Spring Pins are shock-absorbing fastening elements that provide flexibility, uniform strength, equal stress distribution, closer diameter tolerances, no interlocking, trouble-free automatic feeding, and they reduce costs. Heavy, standard, and light duty coiled spring pins provide combinations of strength and flexibility to meet the specific engineering objectives of your pinning applications.

Our objective is to provide our customers with the best value; the lowest installed pin cost. To achieve this objective, our sales strategy focuses on the application engineering approach.

Starting with an analysis of your needs and objectives, our application engineers determine the best SPIROL® coiled pin for the application. Consideration is not only given to the pin but also to the specifications of the components to be assembled and potential assembly problems. Recommendations and samples are provided for your evaluation.

The versatility of the SPIROL® coiled pin makes it the ideal fastener to meet the specific engineering and economic objectives of pinning applications. Our broad range of standard pins is designed to meet most requirements. If a special diameter, length, duty, material, tolerance or pin configuration is needed, we are ready to assist you. Only coiled pins utilize the spiral spring concept…a recognized superior spring design. It imparts to SPIROL® coiled pins unique features not found in other spring pins. More than fasteners, SPIROL® coiled pins are also shock absorbing elements which are integral, active components of a total assembly.


The spiral spring concept represents broad design latitude in the control and development of pin flexibility. The engineered flexibility of SPIROL® coiled pins provides for compression of the pin into the hole and for continued flexibility after insertion. Without this flexibility, the total load applied to the pin would be transmitted to the hole wall without dampening the impact. Since the hole material is normally softer than the pin, elongation or enlargement of the hole would result. The fit between the hole and the pin would become loose, increasing the impact force and accelerating the rate of hole damage. The inevitable result would be premature failure of the assembly. In properly engineered applications, the flexibility of SPIROL® coiled pins dampens shock and vibration, thus eliminating hole damage on all the components of the assembly resulting in maximum product life.


Force direction does not affect the flexibility and shear strength of the SPIROL® coiled pin. Compression causes the pin to coil from the outer edge inwardly towards the center. When loads are applied and relieved, as happens in shock and vibration, the pin contracts and expands in unison. Application of an excessive load compresses the pin into a solid tube. Further loading causes shear failure. In properly engineered applications, this condition should not occur.


Stresses imparted to the pin during installation compression, as well as stresses resulting from applied loads, shock and vibration, are distributed equally throughout the SPIROL® coiled pin cross section. This concept and uniform flexing and strength are related and inherent features of the spiral design. Stress concentration results in a weak point where progressive shear failure starts and premature fatigue occurs. SPIROL® coiled pins have no weak points of stress concentration.


Flexibility, strength, and diameter must be in the proper relationship to each other and to the mating host materials to maximize the unique features of the SPIROL® coiled pin. Strength and flexibility must be balanced. A pin too strong for the applied load would not flex, causing damage to the hole. A pin not strong enough would flex too much and fatigue. Balanced strength and flexibility must be combined with a large enough pin diameter to transmit applied loads without damaging the hole wall. That is why SPIROL® coiled pins are offered in different provide a variety of combinations of strength, flexibility and diameter to suit different mating host materials.

Download the 2D/3D drawings of SPIROL's Coiled Spring Pins