Compression Springs Resources | Helical Compression Spring Design

Common Compression Spring Design Terms

Per Spring Manufacturers Institute Handbook of Spring Design, commonly used compression spring terminology includes:

d wire diameter
I.D. Inside Diameter
O.D. Outside Diameter
D. Mean coil diameter = (O.D. + I.D.)/2 or O.D. – d
L_f Free Length = The overall length of a compression spring in the unloaded position.
P Pitch = The distance from center to center of the wire in adjacent active coils. Recommended practice is to specify the number of active coils rather than pitch.
C Spring Index = D/d = ratio of mean coil diameter (D) to wire diameter (d). The preferred index range is 4 to 12. Helical springs with high indexes tangle and may require special packaging. Springs with indexes lower than 4 are difficult to form.
e_s Squareness = Angular deviation between the axis of a compression spring and a normal to the plane of the ends. Squareness can be measured by standing a sample spring on end on a horizontal flat plate and bringing the spring against a straightedge at right angles to the plate. The helical compression spring is rotated to produce a maximum out-of-square dimension es. Normally squared and ground springs are square within 3º when measured in the free position.
e_p Parallelism refers to the relationship of the ground ends, and is determined by placing a spring on a flat plate and measuring the maximum difference in free length around the spring circumference.
Bearing Surface: To improve squareness and reduce buckling during operation, a bearing surface of at least 270º is required. Squared and ground compression springs are normally supplied with a bearing surface of 270º to 330º. Additional grinding results in thin sections.

Compression Spring Design Capabilities and Resources

Compression Spring Wire Diameter

Whatever your compression spring design needs, Master Spring has the capabilities to match. We have a wide range of CNC coiling machines that can manufacturer custom compression springs with wire diameters as small as 0.006” or as large as 0.276” (0.15 mm to 7.0 mm) and any size wire in between.

Compression Spring Materials

We manufacture custom compression springs from all types of material. The most common material types for compression springs are music wire, stainless steel (type 302, type 316 and type 17-7 PH), hard drawn, chrome silicon, and phosphor bronze. With our diverse selection of springs and wire forms and our industry expertise, we can create intricate custom springs other manufacturers simply will not quote.
Common Compression Spring Materials Include:

High Carbon Spring Wire
Carbon and Alloy Wire
Hard Drawn Wire
Alloy Steel Wire
Stainless Steel Wire
Non-ferrous Alloy Wire
And Many More!

Download Properties of Materials Guide

Body Shapes of Compression Springs

Master Spring manufactures four different shapes of compression springs. The parameter that differs from one shape to the next is the spring’s outside diameter.

Straight Cylindrical Compression Springs (constant outside diameter)
Conical or Tapered Compression Springs
Barrel Compression Springs
Hourglass Compression Springs

Compression Spring Design Considerations

Within each of these compression spring shapes outlined above, three additional parameters will determine the shape and, more importantly, the function of the compression spring:

Ends Closed or Open: The ends can either be closed or open. The most common end types are closed. Closed coil springs have the last 2 coils on each end touching each other so that the spring stands up straight. The last closed coil on each end is called a dead coil because it is not free to deflect under load.
Ends Ground or Not Ground: For closed coil springs, the ends can be ground or not ground. Ends may be ground to decrease the solid height of the spring and/or to help the spring stand up straight.
Constant or Variable Pitch: The pitch can be constant or variable. The pitch is the distance from center to center of the wire in adjacent active coils. Recommended practice is to specify the number of active coils rather than pitch. Active coils are the coils which are free to deflect under load. The number of active coils determines the spring’s rate and loads.

Compression Spring Production

As a leading compression spring supplier, we use state-of-the-art CNC coiling machines with in-line monitoring cameras and sorters. Our in-line cameras and sorters monitor the outside diameter and free length of each spring and sort out any springs that are out of tolerance. We grind the ends of compression springs if ground ends are required.

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Need a custom wire form or coil spring? We make it work. Fill out the contact form and a representative will respond within 1 business day. Please attach a PDF or CAD file with your request to quote.

Custom Compression Spring Resources

Common Compression Spring Design Terms

Compression Spring Specification Checklist

Compression Spring Design Capabilities and Resources

Contact Master Spring