Compression Spring Component Generator dialog box - Calculation tab

Sets parameters for calculation of a compression spring. You can calculate generator data based on selections made in the Design tab.

Access:

Ribbon: Design tab Spring panel Compression and click the Calculation tab.

Spring Strength Calculation

Compression Spring Design	Dimension design of compression spring for the specified spring load.
Spring Check Calculation	Calculation of assembly dimensions and a compression spring strength check for the specified load and spring dimensions.
Work Forces Calculation	Calculation of forces induced by the compression spring of specified dimensions.

Calculation Options

Select the options for spring calculation.

Design Type	Note: This option is available only if you select Compression Spring Design in the Spring Strength Calculation area.
	F, Assembly Dimensions d, L 0 , n, D	Suitable wire diameter, number of coils, and spring diameter are designed for the specified load F 1 , F 8 and assembly dimensions L 1 , L 8 , H of the compress spring.
	F, D d, L 0 , n, Assembly Dimensions	Suitable wire diameter, number of coils, length, assembly dimensions L 1 , L 8 , H of the spring are designed for the specified load F 1 , F 8 and the compress spring diameter.
	F 8 , D, Assembly Dim. d, L 0 , n, F 1	Suitable wire diameter, number of coils, spring length and required force F 1 in the pre loaded state are designed for the specified working force F 8 , diameter, assembly dimensions L 1 , L 8 , H of the compress spring.
Method of Stress Curvature Correction	Use the drop-down list to select the method of stress curvature correction.
	With helical springs, the stress appearing in the spring coils at the given loading is calculated for simple torsion. Additional bending stress appears in the coil due to its rounding. Therefore, the stress is corrected in the calculation using a correction coefficient. As several different coefficients are commonly used, choose from the list the correction coefficient which meets your local usage or recommendations of standards.
	Note: From the view of strength check of a spring exposed to static loading, using the correction coefficient from Gahner gives the best results.
	Hint: With springs exposed to static loading, corrections are usually not executed.
Design of Assembly Dimensions	Note: This option is available only if you select Compression Spring Design in the Type of Strength Calculation area and F, D d, L0, n, Assembly Dimensions in the Design Type drop-down list.
	Design of All Assembly Dimensions L 1 , L 8 , H	Pre loaded Spring Length L1 is Specified.
	Min. Load Length L 1 is Specified	Suitable wire diameter, number of coils, length, assembly dimensions L 1 , L 8 , H of the spring are designed for the specified load F 1 , F 8 and the compression spring diameter.
	Max. Load Length L 8 is Specified	Designs corresponding working deflection and length of pre loaded spring for the specified load, diameter and length of fully loaded spring.

Load

Used for input forces specifications.

Note: This option is not available in case of Work Forces Calculation.

Dimensions

Enter or measure the spring dimensions.

Spring Coils

Rounding of Coil Number	Set the value for rounding the coil number value.
Active Coils	Specify the spring number of active coils.

Spring Material

Select the spring material and its properties. Click to open the Material Database where you can select the appropriate material.

Warning: Strength parameters of material are determined empirically and reflect minimum values applicable for a group of materials. Although these values are close to the values obtained using measurement of particular materials, it is recommended in cases of final calculations to use the parameters of material according to the material sheet or specifications of the producer.
Material	Specify material or select it from Material Database.
	If a material is selected from the Material Database, its values are inserted automatically into the following edit fields, and the edit fields are locked. To unlock the fields clear the box.
Ultimate Tensile Stress	Enter the ultimate tensile stress of the spring material.
Allowable Torsional Stress	Enter the allowable torsional stress of the spring material.
Modulus of Elasticity in Shear	Enter the modulus of elasticity of the spring material.
Density	Enter the density of the spring material.
Utilization Factor of Material	Enter the utilization factor of the spring material. Click next to the edit field to open a dialog box where you can set the value.
	The coefficient gives a relation between the torsion stress of a spring in the fully loaded state and the allowable torsion stress, such as u S » τ 8 / τ A . If a greater value is selected, less material is needed for spring production, the spring dimensions and the space for mounting are less, but the securing of spring stability during its function is lower, and vice versa. Therefore this coefficient is in fact a reciprocal value of the safety rate. For common operational conditions, the value of the utilization factor of the material is recommended to be within the u S = 0.75 ... 0.95 range. Lower values may be used for springs working in aggressive surroundings, at high temperatures or loaded with impacts.
	The value of the utilization factor of the material is selected in a dialog box where a range of recommended values is designated.

Check of Buckling

Check the box to enable to input or measure values.

Use the drop-down list to select an option.

Fatigue Loading

Check the box to enable to input or measure values.

Use the drop-down list to select an option.

Safety Factor

Enter the safety factor of the spring material. Click next to the edit field to open a dialog box where you can set the value. The coefficient is used when calculating dynamically loaded springs (cyclic fatigue load for life N > 10 5 working strokes). Is given by a ratio between the endurance limit of spring and the torsional stress of spring material exposed to full load, such as k f » τ*** e / τ 8 . For standard operating conditions the recommended value of safety factor at fatigue limit k f is recommended to be in the range of 1.1 ... 1.5. In general, use higher k f values for springs working in corrosive environment, at high temperatures or under impact loads. The effect of a corrosive environment has a significantly serious influence on the spring fatigue strength, since it can reduce the spring loading capacity down to one fifth, depending on the material and type of corrosive environment. The value of the safety factor at the fatigue limit is selected in a dialog box where a range of recommended values is specified.

Assembly Dimensions

The drop-down list is not enabled if you select the F, D d, L ₀ , n, Assembly Dimensions in the Design Type drop-down list. Work Forces Calculation must be selected in the Spring Strength Calculation area.

H, L 1 L 8	Length of a fully loaded spring is calculated for the specified working deflection and the length of the pre loaded spring.
H, L 8 L 1	Length of a pre loaded spring is calculated for the specified working deflection and the length of fully loaded spring.
L 1 , L 8 H	Working deflection is calculated for the specified lengths of a pre loaded spring and fully loaded spring.

(More)

Displays additional options for spring design. To display the More Options area, click More in the right lower corner of the Calculation Tab.

Design of Working Deflection
Note: Available only if you select Compression Spring Design in the Spring Strength Calculation area, and F, D d, L0, n, Assembly Dimensions in the Design Type drop-down list.
Not Specified	Designs suitable spring working deflection for the specified load and spring diameter.
Minimum Working Deflection	Designs suitable spring working deflection that is larger than the minimum allowable value H min , for the specified load and spring diameter.
Maximum Working Deflection	Designs suitable spring working deflection that is smaller than the maximum allowable value H max , for the specified load and spring diameter.
Deflective Range	Designs suitable spring working deflection that is the nearest to the demanded deflection H', for the specified load and spring diameter.
Design of Spring Diameter
Note: Available only if you select Compression Spring Design in the Spring Strength Calculation area, and F, Assembly Dimensions d, L0, n, D in the Design Type drop-down list.
Not Specified	The smallest suitable spring diameter is designed for the specified load and spring assembly dimensions.
Minimum Diameter	The smallest suitable spring diameter larger than the minimum allowable value D2 min is designed for the specified load and spring assembly dimensions.
Maximum Diameter	Designs suitable spring outside diameter smaller than the maximum allowable value D1 max for the specified load and spring assembly dimensions.
Diameter Range	Designs suitable spring diameter nearest to the demanded diameter D' for the specified load and spring assembly dimensions.

Results

To display the Results area on the right side of the Calculation and Design tabs, double-click the double line on the right or click the chevron.

Displays the calculated dimensions values such as spring mass or wire length. Click Calculate to display the values. The units of the results values can be changed. Double-click the specified value you want to change.

Following output parameters are displayed in the Results pane:

• Space between Springs of Free Coils (a)
• Pitch of Free Spring (t)
• Wahl Correction Factor (K _w )
• Spring Constant (k)
• Min. Load Spring Deflection (s ₁ )
• Total Spring Deflection (s ₈ )
• Limit Spring Deflection (s ₉ )
• Working Spring Deflection (s _work )
• Max. Allowable Spring Deflection (s _max )
• Limit Test Length of Spring (L _minf )
• Theoretical Limit Length of Spring (L ₉ )
• Spring Limit Force (F ₉ )
• Min. Load Stress (τ ₁ )
• Max. Load Stress (τ ₈ )
• Solid Length Stress (τ ₉ )
• Critical Speed of Springs (v)
• Natural Frequency of Spring Surge (f)
• Deformation Energy (W ₈ )
• Wire Length (l)
• Spring Mass (m)

Note: For further description of the calculated parameters in metric or English units, see Engineer's Handbook.

Summary of Messages

Displays the reports about calculation. To open the Summary of Messages area at the bottom of the Calculation and Design tabs, double-click the double line at the bottom of tabs or click the chevron at the bottom of the tabs.

Toolbar commands