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Compression Springs Compression Springs

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Extension Springs Extension Springs

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Torsion Springs Torsion Springs

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Conical Springs Conical Springs

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Initial Tension in Stock Extension Springs

 

The term “initial tension” indicates the beginning tension that is keeping the extension spring’s coils together. It is the force that it takes to separate the extension spring’s coils just enough for you to see light between them or slip a thin piece of paper in them. This term is related to your spring’s force which is an important factor when selecting the right stock extension spring for the job.

Extension spring rate is the constant force your spring exerts per inch of distance traveled. Initial tension will be added to the load generated by the amount of distance traveled, as calculated with the spring rate. However, it will be added in a non-concurring manner. This means that, unlike rate, initial tension will not increment, it will simply be added to the load determined by the spring rate once.

 

What is Initial TensionWhat is Initial Tension

Here is an example of how you can calculate initial tension.

You have an extension spring with a rate (k) of ten pounds per inch and a working load (F) of 20 pounds at a distance traveled (x) of one and a half inches. If you multiply the rate by the distance traveled and subtract the remaining value from the load, you will get the pounds of force of your extension spring’s initial tension (Ti) as shown in the formula below.

Calculate Initial Tension

Ti = F – kx

Ti = 20 – 10 * 1.5

IT = 20 – 15

IT = 5 lbf

Key Terms

- IT = Initial Tension

- L = Load

- R = Rate

- T = Travel

Example Formula Tension SpringExample Formula Tension Spring

 

Once you know the initial tension, you simply add this to the load calculated by the rate in order to get an accurate answer regarding how much force your spring requires to travel a certain distance. For example, if your spring rate says that your spring requires 10lb. of load to extend one inch of travel, and you will extend your spring 2 inches, then you have to multiply those values together to calculate the load. Once you have calculated the load, no matter how many inches your spring extended, you simply add the initial tension. Let’s say the initial tension is 5lb. then, you would actually need 25lb. for it to travel one inch. The formula to solve this example is shown below.

 

Calculate Extension Spring Load

F = xk + Ti

F = 10 x 2 + 5

F = 20 + 5

F = 25lb

Key Terms

- IT = Initial Tension

- L = Load

- R = Rate

- T = Travel

Spring Rate Extension Spring ExampleSpring Rate Extension Spring Example

 

As you can see, initial tension does play an important role, and it is necessary to factor it in, in order to figure out the correct force you need your spring to have. However, you don’t necessarily have to be calculating initial tension all the time. We have simplified this step and provide you with that information automatically when you use our Spring Creator calculator. All you need to do is enter your spring’s physical dimensions, click calculate, and check the spring analysis where you will see what the initial tension of that specific spring is. Should you need additional help or assistance purchasing the perfect extension spring, be sure to contact us directly at: sales@thespringstore.com.

 

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Created by Alfonso Jaramillo Jr
President Acxess Spring
Over 40 Years of Experience in Spring Engineering and Manufacturing