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When a mechanism fails because a spring loses tension too early, the downstream cost in downtime and rework adds up fast. Engineers, makers, and maintenance technicians who need a dependable compression spring with a consistent spring rate turn to wire-formed coil springs made from dedicated spring steel. This listing covers a broad matrix of sizes so you can match the exact free length and outer diameter your design calls for without compromise.
Each spring in this range is wound from 3mm diameter spring steel wire — a carbon-steel alloy selected for its high elastic limit and fatigue resistance. Outer diameters span 26mm to 40mm (approximately 1.02 in to 1.57 in), and free lengths run from 20mm to 100mm (approximately 0.79 in to 3.94 in). The black surface treatment provides a baseline level of oxidation resistance during storage and light-duty service.
Typical use cases include return-force mechanisms in industrial jigs and fixtures, plunger and valve assemblies requiring a defined preload, suspension or damping sub-assemblies in custom robotics and automation rigs, and replacement springs in agricultural or workshop equipment where standard metric coil springs are specified.
| Wire Diameter | 3mm (0.118 in) |
|---|---|
| Outer Diameter (OD) | 26mm – 40mm (1.02 in – 1.57 in) |
| Free Length | 20mm – 100mm (0.79 in – 3.94 in) |
| Material | Spring Steel (high-carbon) |
| Surface Finish | Black (oxidation-inhibiting coating) |
| End Type | See variant options |
| Spring Rate | See variant options |
| Max Load Capacity | See variant options |
| Coil Direction | Right-hand (typical) |
| Pack Size | 1 piece per order |
Start with three key dimensions: outer diameter (OD), free length, and wire diameter. The OD must fit inside your bore or over your guide rod with clearance. The free length should exceed your required working length by enough to generate the preload you need. Wire diameter determines spring rate — a thicker wire produces a stiffer spring at the same coil geometry. Use the Size option above to select the OD and free length combination that matches your design envelope.
Load capacity depends on the specific OD and free length of the variant you select, as these determine the number of active coils and the resulting spring rate. Spring steel with a 3mm wire diameter is suited for moderate-load applications — typically light to medium industrial use. For exact load and deflection data, contact us with your selected size and we can provide further guidance.
The black surface treatment provides baseline oxidation inhibition and is appropriate for indoor, dry, or lightly protected environments. It is not rated for continuous outdoor exposure, salt spray, or high-humidity conditions. For outdoor or corrosive environments, consider stainless steel springs or apply an additional protective coating after installation.
Yes. Springs in the OD 26–40mm range are designed to seat in standard metric spring pockets or over metric guide rods. Ensure your bore diameter is at least 1–2mm larger than the spring OD to allow free compression without side-wall binding, and that your guide rod diameter is at least 1–2mm smaller than the spring's inner diameter.
Spring steel is selected for its fatigue resistance, making these springs suitable for cyclic compression duty in machinery, jigs, and automation equipment. Performance in very high-frequency or extreme-load cycling depends on the specific deflection range and stress level. Avoid compressing beyond the solid height to prevent set and premature fatigue failure.
The inner diameter is approximately equal to the outer diameter minus twice the wire diameter. For example, a 3x30mm OD spring has an approximate ID of 30mm − (2 × 3mm) = 24mm. Exact ID values may vary slightly due to manufacturing tolerances; contact us if you need a confirmed ID for a specific variant.
The current listing is configured for single-piece orders so you can source exactly what you need. If you require larger quantities, please contact us directly — we can discuss volume pricing and fulfillment options for project or production runs.
