Understanding Spring End Options
An important consideration when selecting springs is choosing the right end type for your spring.
The spring end type you choose depends on the application in which the spring will be used. In some cases, a spring may need to have two different end types. In order to select the right end type or types for your springs it is important to understand each end type and how they function.
Spring end type affects the pitch, solid height, number of active and total coils, free length, and seating characteristics of the spring. The following is an introduction to the basic end types available.
There are two basic end types used for compression springs – closed and open. Each option offers the choice of either ground or not ground ends. The most widely used type is a closed or squared off end type. In the case of closed ended springs, the space between the last two coils is minimal so that the coils actually touch and it sits flat. Conversely, open ended springs are not squared off and tend to need some form of support, such as a rod. Open ends are usually only specified in special applications. Grinding the ends of compression springs helps springs sit more flat to reduce buckling. Grinding is a secondary operation, and therefore makes springs more expensive.
Watch our video on compression spring end types
Hooks and loops are the two basic end type options used with extension springs. Loops are fully closed all the way around, and hooks have a gap. In most cases, stock extension springs are made with loop ends. If a hook is required, a gap can easily be cut in the loop to create the hook. Hooks and loops are available in a few different style options to match application needs. The most widely used end styles for extension springs are crossover, machine style, side style, and double loop ends.
Watch our video on extension spring end types
In the case of torsion springs, the most common and versatile end type is a plain straight leg, with no bends. Customized designs are available for applications that require a torsion spring with bends. A sample, print, photo, or sketch is all that a good spring manufacturer will require to determine the torsion spring design that is needed.
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