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Info Letter No. 80 - July/August 2003

by Fritz Ruoss

New European Spring Standards

Edition Beuth (www.beuth.de) released two new DIN books "Federn 1" (No. 29, edition Feb.2003) and "Federn 2". "Federn 1" contains standards about calculation, "Federn 2" about spring materials, heat treatment, quality definitions. The essential standards for calculation and materials are now defined in Euronorms (EN). The contents are identical with the former German DIN standards.

DIN 2089-1 EN 13906-1 Calculation of Helical Compression Springs
DIN 2089-2 EN 13906-2 Calculation of Helical Extension Springs
DIN 2088 EN 13906-3 Calculation of Helical Torsion Springs


Changes of Material Names:

EN89-71 EN 10089 hot-rolled spring steel wire
EN 1654 EN 12166 copper and copper alloys

Material database fedwst.dbf was modified due to changes of material names. You can download fedwst.dbf at the customer site of www.hexagon.de.

FED2+ Loop Types

Reference for loops of extension springs are now the pictures at EN 13906-2, appendix A. images are identical with DIN 2097, but index begins with A.1 (instead of pic.2 at DIN 2097).

FED1-3 Reference to EN Standards at Printout

Headings of the printout refers now to new EN standards, i.e. "helical compression spring calculation EN 13906-1" instead of "helical compression spring calculation to DIN 2089".

FED3+ Tolerance for Torque, Leg Length, Leg Angle

No new Euronorm is available for tolerances of torsion spring dimensions until now, but a newer edition of DIN 2194 was released (Aug.2002). Calculation of max. deviation for torque, leg length and leg angle has been adapted to the latest standard in FED3+.

FED1+ Reduced Life Expectation of Buckling Springs

Bending stress overloads torsion stress (shear stress) if spring begins buckling (sk < s2, error message in FED1+). Goodman diagram and life expectancy calculation cannot consider this effect, real life expectancy is less than the program reports ! There is no known method to calculate influence of buckling for life expectancy. For dynamic applications, you should avoid buckling of the springs at any case !

FED1+ Choice Dimensioning or Recalculation after Change of Material

Now you can select if FED1+ should recalculate number of coils (Dimensioning, spring load unchanged), or spring loads for new material (Recalculation, dimensions unchanged).

SR1 - Bolt Length

Input of bolt length was limited to 1000mm. Now bolt length until 100000 mm is possible.

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