# Conical Springs Nomenclature

### Definition: Conical springs are compression springs which are helically coiled round wires forming a tapered or conical shape. They are used to provide balance and reduce the solid height by the coils telescoping into each other.

##### Tapered

The diagonal shape of a conical spring’s sides.

##### Wire Diameter (WD)

The thickness of the round wire which the compression spring is made of.

##### Large Outer Diameter

The thickness of the larger coil at one end of the compression spring’s body.

##### Small Outer Diameter

The thickness of the smaller coil at the other end of the compression spring’s body.

##### Inner Diameter (ID)

The width of the inside of the smallest coil. Calculate by subtracting two wire diameters from the small outer diameter.

##### Mean Diameter (MD)

The medium or intermediate diameter that is located right in the middle of inner diameter and outer diameter. Calculate by subtracting one wire diameter from the outer diameter or by adding one wire diameter to the inner diameter.

##### Free Length (FL)

The free, unloaded length of a tapered spring.

##### Total Coils (T/C)

The total amount of coils including open and closed coils.

##### Active Coils (A/C)

The open/active coils in your cone spring. You may calculate the active coils by subtracting the closed coils from the total coils.

##### Solid Height (LH)

The length/height of your conical spring when it is fully compressed and all of the coils are touching or have fully telescoped.

##### Pitch (P)

The distance between your spring’s coils.

##### Rise Angle of Coils

Because, there is pitch in between the coils, the wire which the coils are made of rises. This is the measurement of how much the angle of the coil is raised.

##### Index (I)

The proportional ratio between your spring’s wire diameter and mean diameter (measured from both the small and large outer diameters). It specifies the tightness of your compression spring’s coils and the level of manufacturing difficulty.

##### Telescope (Nesting):

When the conical compression spring’s coils perform a telescope effect when being compressed due to the different diameters. The smaller diameter from the top compresses into the next coil’s inner diameter and so on.

##### Travel (F)

The motion in which a conical spring is compressed. The distance traveled is the difference between the free length and the loaded height.

The force being applied on the spring in order for it to travel.

##### Closed Ends

Closed coils without any pitch in it at the edges of the conical springs. (first and/or last coils)

##### Closed and Ground Ends

Closed coils without any pitch in it at the edges of the tapered springs which are ground to help the spring stand straight on a flat surface. (first and/or last coils)

##### Double Closed Ends

Two closed coils without any pitch in it at the edges of the cone springs. (first and/or last coils)

##### Open Ends

All coils of the spring have pitch in between them, including the edges.

##### Endurance Limit

Maximum stress at which your compression spring will perform indefinitely without failure for a given minimum stress limit.

##### Permanent Set

The product of exceeding the elastic properties of a conically tapered cone spring thus keeping it from returning to its original free length once the load has been released.