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When a loose fit, inconsistent return force, or corroded spring causes a mechanism to fail, the entire assembly pays the price. Engineers, hobbyists, and repair technicians who work with miniature devices, precision instruments, or compact mechanical assemblies need compression springs they can rely on — springs that hold their rated dimensions and resist environmental degradation over repeated cycles.
These 304 stainless steel compression springs feature a wire diameter of 0.4 mm and are available across a range of outer diameters (OD) from 3 mm to 10 mm (approx. 0.12 in to 0.39 in) and free lengths from 5 mm to 50 mm (approx. 0.20 in to 1.97 in). Each spring is formed from 304-grade stainless steel wire, wound to a consistent pitch with squared and ground ends for stable seating. Available in packs of 10 or 50 to suit both prototyping and production runs.
Typical applications include miniature electronic enclosures requiring button return force, small valve assemblies in fluid control systems, pen and stylus mechanisms needing consistent click-action compression springs, and precision jig fixtures where repeatable spring deflection is critical.
| Material | 304 Stainless Steel |
|---|---|
| Wire Diameter | 0.4 mm |
| Outer Diameter (OD) | 3 mm – 10 mm (0.12 in – 0.39 in) |
| Free Length | 5 mm – 50 mm (0.20 in – 1.97 in) |
| End Type | Squared ends |
| Spring Rate | See variant options |
| Surface Finish | Bright (natural stainless) |
| Pack Size | 10 pcs / 50 pcs |
| Operating Temperature | See variant options |
| Coil Direction | Right-hand wound (standard) |
Measure the bore or housing your spring will sit in — the spring OD should be slightly smaller than the bore diameter to allow free movement without binding. The free length should exceed your required compressed length by at least the travel distance you need. Check the variant options table for the exact OD and free length combinations available.
Spring rate depends on wire diameter, OD, and number of active coils. With a 0.4 mm wire diameter, these springs are designed for light-duty applications — typically suited for return forces in the range of a few grams to a few hundred grams depending on the specific OD and length. For precise load requirements, contact us to confirm.
Yes. 304 stainless steel offers good corrosion resistance against moisture, mild acids, and atmospheric exposure. It is widely used in outdoor, marine-adjacent, and food-adjacent applications. For highly corrosive environments (e.g., saltwater immersion), 316 stainless steel would be a stronger choice.
Yes. The small wire diameter (0.4 mm) and compact OD range (3–10 mm) make these springs well-suited for button contacts, battery terminals, connector pins, and other PCB-level spring applications where space is constrained and consistent contact force is needed.
Both packs contain identical springs — the only difference is quantity. The 10-piece pack is ideal for prototyping, repair, or low-volume use. The 50-piece pack offers a lower per-unit cost and is suited for production runs, maintenance kits, or stocking multiple sizes.
Yes. The 0.4 mm wire diameter and short free length options (5–15 mm) are commonly used in pen click mechanisms, retractable styluses, and similar consumer product assemblies. Select the OD that fits your pen barrel bore and the free length that matches your required click travel.
Check three dimensions: (1) OD — must be smaller than your housing bore; (2) free length — must be longer than your compressed length by at least the required travel; (3) wire diameter — must clear any guide pin or mandrel used. If you are unsure, order a 10-piece sample pack of the closest size to test fit before committing to a 50-piece order.
