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When a mechanism fails because a tiny spring loses tension or snaps under load, the whole project stalls. Engineers, hobbyists, and repair technicians who work with compact assemblies — electronics, precision instruments, small appliances, and DIY gadgets — need a reliable source of accurately sized compression springs that fit exactly where they're needed.
These spring steel small compression springs feature a wire diameter of 0.5 mm and are available in outer diameters (OD) of 3, 4, 5, 6, 7, 8, 9, and 10 mm (approximately 0.12–0.39 in). Free lengths range from 5 mm to 100 mm (approximately 0.20–3.94 in), with shorter lengths sold in packs of 10 and longer lengths in packs of 5, giving you the right quantity for prototyping or small-batch production.
Typical use cases include spring-loaded battery contacts in portable electronics, return mechanisms in miniature switches and valves, tension-balancing assemblies in precision instruments, and custom jig or fixture components for small-scale manufacturing and maker projects.
| Material | Spring Steel |
|---|---|
| Wire Diameter | 0.5 mm (0.020 in) |
| Outer Diameter (OD) | 3 / 4 / 5 / 6 / 7 / 8 / 9 / 10 mm (0.12–0.39 in) |
| Free Length | 5–100 mm (0.20–3.94 in) — see variant options |
| Spring Type | Compression (closed ends) |
| Coil Direction | See variant options |
| Surface Finish | See variant options |
| Spring Rate | See variant options |
| Pack Size | 5 pcs (lengths 60–100 mm) / 10 pcs (lengths 5–50 mm) |
Measure the bore or housing your spring will sit inside, then select an OD that is slightly smaller than the bore to allow free movement without binding. For a spring that wraps around a rod, choose an ID (inner diameter = OD minus twice the wire diameter) slightly larger than the rod. With a wire diameter of 0.5 mm, the ID ranges from approximately 2 mm (OD 3 mm) to 9 mm (OD 10 mm).
The free length should be longer than the maximum extended position in your assembly. A common rule of thumb is to choose a free length roughly 20–30% longer than the compressed working length, so the spring is never fully coil-bound during normal operation. Review your mechanism's travel distance and select the closest available length from the variant options.
Load capacity depends on the specific OD, free length, and number of active coils. With a 0.5 mm wire diameter, these are designed for light-duty applications — typically in the range of a few grams to a few hundred grams of force depending on the variant. If you need exact spring rate or load data for a specific size, please contact us to confirm before ordering.
Spring steel provides good mechanical properties but has limited inherent corrosion resistance compared to stainless steel. For indoor, dry, or low-humidity environments these springs perform reliably. For outdoor, humid, or chemically exposed environments, consider applying a protective coating or contact us about stainless steel alternatives.
Yes — the closed-end coil geometry provides a flat seating surface compatible with standard spring seats and counterbored housings. Verify that your housing bore matches the selected OD and that the seat depth accommodates the compressed length of the spring you choose.
A larger OD with the same wire diameter and free length will generally produce a lower spring rate (softer feel) and lower load at a given deflection, because the coil diameter increases the lever arm. A smaller OD produces a stiffer spring for the same wire and length. Choose based on the force your mechanism requires and the space available.
Yes — the small wire diameter (0.5 mm) and compact OD range (3–10 mm) make these well-suited for battery contacts, push-button return mechanisms, connector pins, and other PCB or electronics assembly applications where space is limited and precise, repeatable force is needed.
