Extension Spring Design Help
Extension springs are also very common but they aren’t as economical as compression springs due to the fact that these will usually have hooks. In extension spring design help, the process is similar to that of a compression spring. You still have to take into mind its physical dimensions as well as the extended length you wish your spring to travel too and under what amount of load. Extension spring rate is calculated the same way but there is one extra factor you have to take into mind besides rate. You see, extension springs already have a collected amount of energy before being extended. This huddled energy is called initial tension. So when you extend your spring, you will apply the force indicated by the calculation of rate plus the amount of initial tension. Initial tension does not increase in a linear motion like rate does, it is only added once whether you travel one or two inches. The image below provides the formulas and explanation of this operation. The limitations like maximum safe travel considering hook stress and maximum safe load considering hook stress are also a critical part of your design. Missing these important values can eventually cause the hooks of your spring to break. Spring index for extension springs is the same as it is for compression springs or any other spring so make sure your index is no less than 4 to 1 so it won't be that tight so that your spring is able to travel your required distance traveled freely.