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Compression Springs Compression Springs

Enter your Outside Diameter and Free Length
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Inside Diameter
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Free Length
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Wire Diameter
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Total Coils
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Rate
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Material Type
Max. Load
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Max. Deflection
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Solid Height
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*Required Field
Extension Springs Extension Springs

Enter your Outside Diameter and Length Inside Hook
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Outside Diameter
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Length Inside Hook
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Wire Diameter
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Max. Load
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Max. Deflection
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Initial Tension
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Rate
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Material Type
*Required Field
Torsion Springs Torsion Springs

Enter your Outside Diameter and Total Coils
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Inside Diameter
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Total Coils
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Free Position
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Wire Diameter
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Body Length
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Max. Torque
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Max. Deflection
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Rate
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Leg Length
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Material Type
*Required Field
Conical Springs Conical Springs

Enter you Small Outside Diameter, Large Outside Diameter and Free Length
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Small Outside Diameter
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Large Outside Diameter
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Free Length
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Rate
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Total Coils
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Solid Height
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Wire Diameter
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Material Type
*Required Field

Helical Spring Formulas and Equations

There are several different helical compression spring formulas and equations required to complete a design. First, you must focus on your spring’s requirements when it comes to physical dimensions, material type, and working loads. After you’ve set those parameters, the next step is to match the dimensions correctly to achieve the spring’s required function in your application.

When you’ve measured your spring’s surroundings and figured out its environmental requirements, you must set your spring’s tolerances and work within them to achieve the ideal spring design. To the right is a diagram pointing out the term for each dimension. You will also find the formulas used to calculate certain spring dimensions which will help you stay within limits.

How To Measure Helical SpringsHow To Measure Helical Springs

Wire Diameter

 

You can measure the tolerances on outer diameter and inner diameter, but your maximum wire diameter must be calculated. You do this by subtracting the minimum inner diameter from the maximum outer diameter and dividing the result by 2.

d = (Douter – Dinner) ÷ 2

  • d = wire diameter
  • Douter = outer diameter
  • Dinner = inner diameter

 

Solid Height

 

Then you have total coils, which you want to keep at an intermediate number so you can have elasticity. If you have too many, your spring may be elastic but weak. However this is an option some opt for because it allows for a taller solid height. The formula to calculate solid height is total coils plus 1, multiplied by the wire diameter.

 

With all types of ends (except ground):

Lsolid = d(N+1)


With ground ends:

Lsolid = dN

  • Lsolid = solid height
  • d = wire diameter
  • N = total coils
 

Pitch

 

You can then calculate the pitch in between the coils using the free length and the amount of coils you decided to use. You do so by subtracting the amount of wires in the closed coils from the free length and then dividing the result by the active coils.

 

Closed Ends

p = (L–3d) ÷ Na

Closed and Ground

p = (L–2d) ÷ Na

Double Closed Ends

p = (L–5d) ÷ Na

Open Ends

p = (L–d) ÷ Na

  • p = pitch
  • L = free length
  • d = wire diameter
  • Na = active coils

Use these coil spring calculation equations to make sure your spring fits.

closed and squared ends of compression springclosed and squared ends of compression spring

Working Loads and Rate

 

After setting and calculating the physical dimensions, you must move on to your working loads. Your spring’s working loads will determine your spring rate. Find out how much load you will be placing on your spring as well as how much you expect it to deflect under that force.

Both of these factors make up the formula to calculate the required coil spring rate. This formula is dictated in Hooke’s Law where he states “as the extension, so the force”. Hooke’s law simply means that, as your spring compresses/deflects, the load increases proportionally.

 

  • k = L ÷ x
  • k = Rate
  • F = Load
  • x = Travel
working loads and rate of compressino springworking loads and rate of compressino spring

The full equation to calculate the rate of an already established spring design is the following. This formula requires more information than the previous. The material type and its properties have a lot to do with your spring’s rate.

 

D = D outer – d
G = E ÷ 2(1 + V)
k = Gd^4 ÷ (8D^3 x na)

 

  • d = Wire Diameter
  • D outer = Outer Diameter
  • D = Mean Diameter
  • E = Young's Modulus of Material
  • G = Shear Modulus of Material
  • k = Spring Rate
  • na = Active Coils
  • V = Poison's Ration of Material
Robert Hooke - as the extension, so the forceRobert Hooke - as the extension, so the force

If you have a hard time gathering the information, you may simply enter your spring’s dimensions and material type into our spring calculator. Spring Creator will calculate all of the above formulas as well as the elastic limit and maximum load. You may also contact our team to schedule a consultation with our engineers if you’re having a hard time adjusting the design.