# Helical Extension Spring Design Calculator

## Definition: A helical extension spring design calculator is a spring calculation software which calculates spring rate (spring constant), safe maximum deflection, safe maximum loads, and other important spring specifications using your tension spring’s physical dimensions like wire diameter, outer diameter, length inside hooks and material type.

#### What is an Extension Spring?

Extension springs are helically coiled wires wound tightly one on top of the other to absorb energy or maintain tension between two objects. Therefore containing or releasing energy when a load is applied.

Extension springs are used in many devices which serve several different purposes. This means that the design of your helical extension spring is very critical when it comes to the force it exerts as well as its physical dimensions. Even the smallest change to a dimension can critically affect the way your spring functions when it comes to tension spring rate (or spring constant), maximum safe load, and maximum safe travel. For this reason, you must follow certain spring equations or formulas and do various tension spring calculations when it comes to your extension spring design. This is where our helical tension spring design calculator, Spring Creator, comes in to avoid you the trouble of calculating all the formulas and equations by hand.

Below you will find all the information you need to design your helical extension spring including formulas, how-to-measure diagrams, and tips from our spring engineers.

#### Step 1.) What environment will your spring have to resist?

If your spring is required to tolerate high temperatures, moist environments, or needs to be non-magnetic, you must make your design using the correct material or wire type. The material types provided in our helical extension spring design calculator are Music Wire (Spring Steel) ASTM A228, Oil Tempered MB A229, Carbon Valve A230, Hard Drawn ASTM A227, Stainless 17-7 A313, Stainless 316 A316, Chrome Silicon A401, Phosphor Bronze Grade A B159, and Beryllium Copper B197. Different material types have different tensile strengths, therefore this step must be done before going into your helical extension spring design’s calculations due to the fact that changing the material or wire type later on in the process can greatly affect your helical tension spring’s force as well as load and travel tolerances. The most common wire type is Music Wire, also known as Spring Steel. This wire type is also the most economical. If there is no need for high temperature resistance, corrosion resistance, or any other special requisites, this is the material or wire type you want to use.