There are basically four (4) types of ends on helical compression springs: closed & ground, closed & not ground ends, open & ground ends and open & not ground ends.

A spring with closed ends and not ground is the most economical to manufacture and often performs well when the wire size is smaller than .020 and/or the spring index exceeds 12:1.

Closed and ground end springs offer better seating (squareness), which also influences how the axial force produced by the spring is transferred to its mating part, or the mechanism that it works in. Buckling is reduced when the ends of the spring are closed and ground.

Springs that are open and ground are usually produced this way when it is necessary to have a lower solid height and/or more active coils are required to affect the needed rate. Springs with open ends, which are not ground, are normally produced this way when the solid height and rate are not an issue and where the design allows for more generous length tolerance. Open ends are also specified when the spring screws onto a threaded part.

There are several considerations to make when specifying the types of ends on compression springs, including required length tolerances, packaging/tangling issues associated with open wound springs and the ratio of the diameter of the spring to its length.

Additionally, combinations of the types of ends are also available on the same spring, which should be discussed with the springmaker.

-The 18th China(Guangzhou)Int’l Springs Industry Exhibition