Question 1

Initial Tension:

Accepted Answer

The force that tends to keep the coils of an extension spring closed and which must be overcome before the coils start to open

Question 2

Load:

Accepted Answer

The force applied to a spring that causes deflection

Question 3

Loops:

Accepted Answer

Coil like wire shapes at the ends of extension springs that provide for attachment and force application

Question 4

Mean Coil Diameter:

Accepted Answer

Outside spring diameter (O.D.) minus one wire diameter (D)

Question 5

Open Ends, Not Ground:

Accepted Answer

End of compression spring with a constant pitch for each coil

Question 6

Open Ends Ground:

Accepted Answer

“Open Ends, Not Ground” followed by an end grinding operation

Question 7

Passivating:

Accepted Answer

Acid treatment of stainless steel to remove contaminants and improve corrosion resistance

Question 8

Permanent Set:

Accepted Answer

A material that is deflected so far that its elastic properties have been exceeded and it does not return to its original condition upon release of load is said to have taken a “permanent set”

Question 9

Pitch:

Accepted Answer

The distance from center to center of the wire in adjacent active coils (recommended practice is to specify number of active coils rather than pitch)

Question 10

Rate:

Accepted Answer

Change in load per unit deflection, generally given in pounds per inch

Question 11

Remove Set:

Accepted Answer

The process of closing to solid height a compression spring which has been coiled longer than the desired finished length, so as to increase the apparent elastic limit

Question 12

Set:

Accepted Answer

Permanent distortion which occurs when a spring is stressed beyond the elastic limit of the material

Question 13

Solid Height:

Accepted Answer

Length of a compression spring when under sufficient load to bring all coils into contact with adjacent coils

Question 14

Spring Index:

Accepted Answer

Ratio of mean coil diameter (D) to wire diameter

Question 15

Squared and Ground Ends:

Accepted Answer

Refer to closed and ground ends

Question 16

Squared Ends:

Accepted Answer

Refer to closed ends

Question 17

Stress Relieve:

Accepted Answer

To subject springs to low temperature heat treatment so as to relieve residual stresses

Question 18

Shot Peening:

Accepted Answer

A cold-working process in which the material surface is peened to induce compressive stresses and thereby improve fatigue life

Question 19

Squareness of Ends:

Accepted Answer

Angular deviation between the axis of a compression spring and a normal to the plane of the ends

Question 20

Total Number of Coils:

Accepted Answer

Number of active coils (n) plus the coils forming the ends

Glossary of Spring Terminology