0.3/0.4/0.5/0.6/0.7/0.8/0.9mm 304 Stainless Steel Compression Springs L=60-100mm

Wire diameter directly affects spring rate and load capacity — thicker wire produces a stiffer spring. For light-duty return or preload applications (switches, sensors, small levers), 0.3–0.5 mm wire is typically sufficient. For applications requiring more force or resistance to set under sustained load, select 0.6–0.9 mm wire. If you know your required load and deflection, use a spring rate calculator with the OD and free length to confirm the wire size before ordering.

The outside diameter of the spring should be slightly smaller than the bore or pocket it sits in — typically 0.2–0.5 mm clearance on the OD is a good starting point. For a shaft-guided spring, the inside diameter (OD minus 2× wire diameter) should be slightly larger than the shaft. Use the OD options (3–12 mm) in the variant selector and verify against your mechanical drawing before ordering.

304 stainless steel has good fatigue resistance for light-to-medium cyclic loads when the spring is not compressed beyond its solid height. To maximize service life, design your assembly so the spring operates within 80% of its maximum deflection range. Avoid compressing to solid height repeatedly, as this causes set (permanent length reduction) over time.

304 stainless steel offers significantly better corrosion resistance than standard carbon steel springs. It performs well in humid indoor environments, light outdoor exposure, and mild chemical contact (dilute acids, cleaning agents). It is not suitable for prolonged immersion in chloride-rich environments (e.g., saltwater) — for those conditions, 316 stainless would be more appropriate. For typical workshop, electronics, and instrument use, 304 is a reliable choice.

Yes — the OD range of 3–12 mm covers the most common spring pocket sizes used in FDM 3D-printed assemblies and CNC-machined fixtures. When designing a pocket for a 3D-printed part, add 0.3–0.5 mm clearance to the nominal OD to account for print tolerances. For CNC parts, standard H7 bore tolerances work well. Always confirm the free length (60–100 mm) fits within your available travel before selecting a variant.

304 stainless steel provides good resistance to atmospheric corrosion and humidity, making these springs suitable for outdoor enclosures, garden equipment mechanisms, and marine-adjacent (but not direct saltwater) applications. For direct saltwater or highly corrosive chemical exposure, consider upgrading to 316 stainless steel springs. In typical outdoor or humid workshop conditions, 304 will outlast carbon steel springs significantly.

Select the free length based on your required working length plus the compression travel your assembly needs. A spring compressed to 70% of its free length is a common design target. For example, if you need 20 mm of travel and want to work at ~70% compression, a 100 mm free-length spring compressed to 80 mm gives you that range. Always leave at least 10–15% of the free length as a buffer above solid height to prevent coil clash.