Explanation of Terms - Compression Springs
Matl. Spec. - The type of spring wire used.
Dir. of Coil (R/L) - Coil direction can be either right-hand or left-hand. A right-hand spring looks the same as a right-hand thread on a bolt. If two springs are used inside one another, one should be right-hand and the other should be left-hand to avoid tangling.
Wire Diam. (d) - The size of spring wire used.
Coil O.D. - The outside diameter of the coil.
Coil M.D. - The mean (average) of the outside and inside diameters.
Coil I.D. - The inside diameter of the coil.
Spring Index (D/d) - The ratio of coil M.D. to wire diameter. For ease of manufacturing, this value should stay between 5 and 10 if possible.
Free Length - The length of the spring when no force is being applied.
Solid Height - The height of the spring when fully compressed.
Solid Travel - The amount of travel from free length to solid height.
Set Height - The height of the spring at which it will take a "set". "Set" refers to the condition where the spring is compressed so far that its elastic properties have been exceeded and it won't return to its free length when the compressive force is removed; the new free length will be shorter than the original free length.
Set Travel - The amount of travel from free length to set height. As long as the travel of the spring in application doesn't exceed the set travel, it won't take a "set".
Active Coils - The number of coils affecting the load rate of the spring.
Total Coils - The number of active coils plus the end coils.
Pitch - The distance from a point on one coil to the corresponding point on the next adjoining coil.
Spring Weight - The weight of the spring.
Load Rate - The amount of force exerted by the spring for every one inch of travel. It depends upon the wire diameter, coil M.D. and number of active coils.
Type of Ends (O/C P/G) - The type of ends used on each end on the spring.
Finish - The type of finish to be applied to the spring; painted, etc.
