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F E D 9 +

Spiral Spring Design Software

(C) Copyright 1999-2024 by HEXAGON Software, Berlin


FED9 calculates torque and bending stress of spiral springs of flat steel or round wire. Characteristic curves and scale drawings can be displayed graphically and exported as DXF files to CAD.


In pre-dimensioning, only the torque and the elevation angle are entered. FED9 then roughly calculates the dimensions of the appropriate spiral spring.


In dimensioning, FED9 calculates an appropriate spiral spring form spring torque elevation angle, interior and exterior coil diameter and working temperature.


To check an existing spiral spring, enter its dimensions and spring angle in re-calculation. FED9 then calculates the torque for different angles of twist.


The result printout incudes all input and result data. The excerpt shows the most important spring data, abbreviated, on one page. There is also a feature for output of a HTML document for Intranet/Internet and OLE interface for MS-Excel.

Spring Drawing

FED9 generates true-scale spiral spring drawings which can be exported to CAD as DXF or IGES files.


Spring characteristic curves and diagrams of tensile strength and bending stress dependent on the wire thickness are shown on screen. The diagramms can be printed or exported to CAD.

Goodman Diagram

The working area of the selected materials for the calculated spiral spring is shown in the fatigue strength diagram. You can see whether or not the permissable travel tension has been adhered to for dynamically stressed springs. The curves for fatigue strength (>10 million), as well as for 1 million and 100,000 load cycles are shown.

Quick Output

The Quick output allows the characteristic spring curve to be displayed on one screen along with the most important spring data.

Material Data Base

The characteristic data of the most important spring materials (tensile strength, perm. shearing stress in relation to bar diameter, shearing modulus, E-modulus, density) is taken by FED9 from the integrated data base. The DBF file can be edited and appended by the user.

Production Drawing, Animation, Quick4

FED9+ generates a production drawing of the spiral spring. In an animation you can simulate movement of the spiral spring between different position angles. Quick4 generates drawings, tables and diagrams in an ISO 7200 drawing frame.

Help System

You can display a help window for each input value. There are also auxiliary pictures for each symbol used, and each calculation formula. FED9 displays warnings when values are exceeded. For each error message you can display a more detailed description of the error and a remedy suggestion.

Hardware and Software requirements

FED9 is available as 32-bit or 64-bit application for Windows 11, Windows 10, Windows 7.

Scope of Delivery

The FED9 program (incl. sample data, auxiliary pictures, help texts), user manual (pdf), license for unlimited time use.


HEXAGON gives a 24 month guarantee on full functionality of the software.

Information and Update Service

HEXAGON Software is continuously improved and updated. Customers are regularly informed about updates and new editions.

Download FED9 Demo (641 kB)