What is initial tension (extension spring)?
Extensions springs require a certain amount of force to be applied before any deflection is realized. Deflection is the point where the coils start to separate and the spring extends. Once the initial tension is reached and the spring will start to expand at the predetermined rate of the spring. For example if a spring has an initial tension of 20 lbs. and the spring rate is 15 lbs./in.. It will take 35 lbs of force to pull the spring apart one inch, 20 lbs. of initial tension and 15 lbs of spring rate. To expand it to two inches it will take 50 lbs of force, 20 lbs of initial tension and 15 lbs for each inch. And so on and so on. • How long will a spring last? A correctly designed spring, without any extraordinary stress will last indefinitely. Designing a spring based on its operating environment is necessary to increase the life of the spring. If the spring is in a corrosive environment, or under extreme temperatures, the proper material must be used in the design of the spring. Usi
