Understanding Compression Spring End Types
For compression springs there are two basic end type options – closed or open, with both options having either ground or not ground ends. The most commonly used type is a closed or squared off at the end. On closed ended springs, the space between the last two coils is reduced so they touch each other. This squares off the ends so it sits flat. Open ended springs are not squared off and typically need a rod or other form of support to hold it upright. Typically open ends are used only in special applications.
Grinding the ends of compression springs is a secondary operation. While it is more expensive, grinding helps springs sit more flat to reduce buckling. It also makes the free length and spring rate more precise. Typically, grinding is not needed on smaller springs and it is usually avoided on large commercial production runs to reduce costs.
Closed and ground compression spring ends are the most common and sit the most flat, but they are the most expensive. They are ideal for larger springs and precision applications. Closed and not ground springs are best used on smaller springs and large production runs.
Open and ground springs are used in special applications. They will typically need some form of support to stand up. Open and not ground springs are also only used in special situations and require some manner of support.