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When a mechanism fails because a tiny spring loses tension or collapses under load, the cost is far greater than the part itself. Engineers, repair technicians, and precision hobbyists who work with miniature assemblies need small compression springs they can rely on — parts that hold their rated load cycle after cycle without set or fatigue. These small compression springs are wound from 0.4mm wire and cover a broad selection matrix to keep your bench stocked for whatever comes next.
Each spring is wound from 0.4mm (approx. 0.016 in) round wire. Outer diameters span 2.0 mm to 5.0 mm (approx. 0.079–0.197 in), and free lengths run from 5 mm to 25 mm (approx. 0.197–0.984 in). The full size matrix — 42 distinct Size combinations across 6 OD groups — lets you dial in the exact spring rate and travel your design requires. Packs of 10, 50, or 100 pieces are available to match prototype or production quantities.
Typical applications include electronic device button mechanisms requiring consistent return force, precision instrument assemblies such as calipers and gauges, miniature valve and actuator returns in pneumatic or hydraulic micro-systems, and RC model or robotics linkage preloading where a compact spring with a defined free length is essential.
42 distinct Size combinations: OD 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 mm × free lengths 5, 8, 10, 12, 15, and 25 mm — one listing covers a full range of miniature spring needs.
Consistent 0.4 mm (0.016 in) wire gauge across all sizes ensures predictable spring rate behavior and uniform coil geometry for repeatable assembly.
Tightly wound end coils provide flat, stable seating surfaces that distribute load evenly and reduce lateral buckling in confined spring pockets.
Choose 10 pcs for prototyping, 50 pcs for small-batch production, or 100 pcs for ongoing maintenance stock — all from the same verified size variant.
Surface treatment helps resist oxidation in typical indoor environments, extending service life in instruments, electronics enclosures, and light mechanical assemblies.
Each batch is wound to consistent free-length and OD tolerances, reducing the need for hand-selection when fitting springs into tight-tolerance bores or seats.
| Wire Diameter | 0.4 mm (0.016 in) |
|---|---|
| Outer Diameter (OD) Range | 2.0 mm – 5.0 mm (0.079 – 0.197 in) |
| Free Length Range | 5 mm – 25 mm (0.197 – 0.984 in) |
| Available OD Options | 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 mm |
| Available Length Options | 5, 8, 10, 12, 15, 25 mm |
| Spring Type | Compression (open-coil, closed ends) |
| Coil Direction | See variant options |
| Spring Rate | See variant options |
| Material | See variant options |
| Surface Finish | See variant options |
| Pack Quantities | 10 pcs / 50 pcs / 100 pcs |
Match three key dimensions to your assembly: outer diameter (OD) must fit inside the bore or over the guide pin with clearance, free length must exceed your required working length, and wire diameter determines spring rate. For this listing, OD runs 2.0–5.0 mm and free length runs 5–25 mm. Select the Size variant that fits your bore and travel, then verify the spring rate meets your load requirement before committing to a production quantity.
Spring rate varies by OD and free length combination — a shorter spring with a smaller OD will be stiffer than a longer spring with a larger OD at the same wire diameter. Exact rate values per size are not listed here; if your application requires a specific rate in N/mm or lbf/in, please contact us with your size selection and we can provide available data or direct you to the appropriate variant.
These springs carry a surface treatment that provides resistance to light oxidation in typical indoor environments — suitable for electronics enclosures, instruments, and light mechanical assemblies. For continuously wet, salt-spray, or chemically aggressive environments, a stainless steel spring would be more appropriate. Contact us to confirm material and finish details for your specific environment before ordering.
Yes — the OD range of 2.0–5.0 mm is designed to seat in standard miniature spring pockets. For guide-pin mounting, the inner diameter (ID) equals OD minus twice the wire diameter (0.4 mm × 2 = 0.8 mm), so a 3.0 mm OD spring has an approximate ID of 2.2 mm. Ensure your guide pin diameter is at least 0.1–0.2 mm smaller than the ID to allow free compression without binding.
The 10-piece pack is ideal for prototyping, repair, or low-volume builds where you need a small quantity to validate fit and function. The 50-piece pack suits small-batch production runs or maintenance kits. The 100-piece pack offers the best per-unit value for ongoing production, stocking a service bench, or applications where springs are consumable items replaced at regular intervals.
Yes — the 2.0–5.0 mm OD range and 5–25 mm free lengths are well-suited for button return mechanisms, battery contact springs, connector retention, and PCB-mounted spring contacts. The consistent wire diameter and coil geometry ensure repeatable actuation force across a production batch, which is important for tactile consistency in consumer electronics.
The minimum order is 10 pieces per size variant. Bulk pricing is built into the 50-piece and 100-piece pack options — the per-unit cost decreases as quantity increases. For quantities beyond 100 pieces or custom size requirements, please contact us directly to discuss volume pricing and lead times.
