Helical Spring Design Guide.xls

Outline Calculation Procedure

1. Purpose of calculation
   The design of a helical spring using mechanical design formula and material lookup tables.
   Check dimensional limits, strength limits and buckling limits against the operational requirements.
   
   
2. Calculation Reference
   https://roymech.org/Useful_Tables/Springs/Springs_helical.html
   http://www.thecartech.com/subjects/machine_elements_design/helical_springs.htm
   
   
3. Calculation Validation
   Formulas checked using the XLC add-in
   
   
4. Calculation Units
   
   
5. Sketch
   
   
6. Main Input Parameters
   Wire diameter
   Spring mean diameter
   Free length
   Number of turns
   % length on installation and operational max compression
   
   
7. Spring Ends
   Number of inactive turns due to closed and ground ends
   Effective number of turns
   Length modifier
   Inactive Length
   Active Length
   Pitch (unloaded).
   Solid Length
   
   
8. Material Properties
   Material Constant
   Material index
   Ultimate Tensile Stress
   Torsional yield to tensile ultimate strength factor
   Torsional yield stress
   Conversion Factor from Mpa to selected system of units
   Torsional yield stress converted to select system of units
   Young's Modulus
   Modulus of rigidity assuming a Poisson's ratio of 0.3
   
   
9. Spring Deflection Characteristics
   Spring Index
   Spring Rate
   Force to close the spring
   
   
10. Spring Strength Characteristics
    
    Wahl factor
    Torsional Stress Rate
    Force to yield spring
    Spring extension to yield spring
    
    
11. Spring Buckling
    
    Buckling critical compression length
    Buckling force
    
    
12. Operational Limits
    Installed Length
    Installed force
    Operating Length
    Maximum working load

    Calculation Reference
    Machine Design
    

Elements of Mechanical Design

Design of Springs