Compression Spring Various Size 28-32mm Diameter& 20-305mm Length Pressure Small

Measure the inner diameter of the spring seat or guide bore in your assembly. The spring's outer diameter should be 0.5–1.5 mm smaller than the bore to allow free movement without binding. For example, if your bore is 30 mm, a 28 mm or 29 mm OD spring is typically the correct fit.

Free length should be long enough to maintain contact force at maximum extension, yet short enough to avoid coil bind at full compression. As a starting point, choose a free length roughly 1.5–2× the desired compressed (working) length. Refer to your mechanism's travel specification for the exact figure.

Load capacity depends on wire diameter, outer diameter, free length, and number of active coils — all of which interact. The 3 mm wire diameter used here is suited to light-to-medium duty applications. If you have a specific load requirement in Newtons or pounds-force, please contact us to confirm suitability before ordering.

The springs carry a surface treatment that provides resistance to light moisture and humidity typical of indoor workshop conditions. For outdoor, high-humidity, or chemical-exposure environments, additional protective measures (such as a light coat of oil) are recommended. Contact us to confirm the specific finish for your chosen variant.

Yes. The outer diameters (28, 29, 30, 32 mm) and 3 mm wire diameter conform to common metric spring standards, making them compatible with most metric spring seats, guide rods, and pneumatic valve bodies designed for this OD range. Always verify the bore clearance and end-type requirements of your specific assembly.

If you need a single replacement spring, the 1 pc option is the most economical choice. The 2 pc pack is ideal when you need a matched pair (e.g., symmetrical jig fixtures or dual-spring valve assemblies) or simply want a spare on hand. Note that longer lengths (120 mm and above) are available in the 1 pc pack only.

Absolutely. The 28–32 mm OD range and 3 mm wire diameter are commonly specified in DIY automation platforms, CNC Z-axis counterbalance assemblies, and robotic gripper return mechanisms. Select the free length that matches your axis travel and preload requirements.

All four share the same 3 mm wire diameter, so the primary differences are the inner diameter (ID), the spring rate, and the bore size they fit. A larger OD with the same wire diameter generally yields a lower spring rate (softer feel). Choose based on your bore size and the load-deflection curve your application requires.