Engineering and Tolerance

Learn About: Round Wire Compression Springs

Compression Springs are open-coil helical springs wound or constructed to oppose compression along the axis of wind. Helical Compression is the most common metal spring configuration. These coil springs can work independently, though often assembled over a guide rod or fitted inside a hole. When you put a load on a compression coil spring, making it shorter, it pushes back against the load and tries to get back to its original length. Compression springs offer resistance to linear compressing forces (push), and are in fact one of the most efficient energy storage devices available.

The conventional compression spring, the straight metal coil spring, has the same diameter and pitch for the entire length. This configuration is the standard coil type for Lee Stock Compression Springs. Custom configurations can have variable diameter, pitch, or both such as hourglass (concave), conical, and barrel (convex) types.

Ends: All Lee Spring Stock Compression Springs, except Bantam™ Mini Springs (prefix CB), Instrumentation Series (prefixes CI and CIM) and Lite Pressure™ Series (prefix LP), feature squared and ground ends. Ground ends provide flat planes and stability. Squareness influences how the force produced by the spring can be transferred to adjacent parts. Although open ends may be suitable in some applications, closed ends afford a greater degree of squareness. Squared and ground ends are particularly useful in applications in which 1) high-duty springs are specified, 2) unusually close tolerances on load or rate are needed, 3) solid height must be minimized, 4) accurate seating and uniform bearing pressures are required and 5) a tendency towards buckling must be reduced.

Compression Springs are found in a wide variety of applications ranging from automotive engines and large stamping presses to major appliances and lawn mowers to medical devices, cell phones, electronics and sensitive instrumentation devices. The most basic installation is anywhere requiring a push button. Conical type springs are generally used in applications requiring low solid height and increased resistance to surging.

Key Parameters
Unit of Measures: Lee Spring's Stock Springs are specified in both Imperial (inch and pound) and Metric units.Be sure to select the preferred unit of measure when looking for a Stock Spring using Lee Spring's search engines.

Dimensions: Outside Diameter, Inside Diameter, Wire Diameter, Free Length, and Solid Height.
Free Length is the overall length of a spring in the unloaded (at rest) position. 
Solid Height is the length of a compression spring under sufficient load to bring all coils into contact with adjacent coils.

Spring Rate (stiffness): Spring Rate is the change in load per unit deflection in pounds per inch (lbs/in) or Newtons per millimeter (N/mm).

Stress: The dimensions, along with the load and deflection requirements, determine the stresses in the spring. When a compression spring is loaded, the coiled wire is stressed in torsion. The stress is greatest at the surface of the wire; as the spring is deflected, the load varies, causing a range of operating stress. Stress and stress range govern the life of the spring. The wider the operating stress range, the lower the maximum stress must be to obtain comparable life. Relatively high stresses may be used when the operating stress range is narrow or if the spring is subjected to static loads only.

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