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When a standard off-the-shelf spring fails to fit your assembly — too short, too wide, or too soft — you lose time hunting for a replacement and risk delaying your build. Engineers, makers, and maintenance technicians who work with custom jigs, automation fixtures, or mechanical assemblies need a reliable source of precisely sized compression springs they can order by exact dimension.
These compression springs are manufactured from spring steel wire with a wire diameter of 3mm (0.118 in). The outer diameter spans 16–25mm (0.63–0.98 in) and the free length ranges from 20–200mm (0.79–7.87 in). The black surface finish is consistent across the range and provides a degree of corrosion resistance suitable for indoor mechanical environments.
Typical use cases include return-force mechanisms in industrial tooling, plunger and valve assemblies in fluid control systems, and load-bearing suspension elements in robotics and 3D printer Z-axis carriages — all applications where a 3mm wire dia compression spring with a defined OD and free length is specified by design.
Made from spring steel wire (3mm diameter) for consistent elastic return and resistance to permanent set under repeated compression cycles.
OD 16–25mm and free length 20–200mm available as selectable variants — find the exact dimension your design calls for without custom fabrication.
Uniform black surface treatment across all sizes provides a clean appearance and a baseline level of corrosion protection for indoor applications.
3mm wire diameter maintained across the full OD and length range, ensuring predictable spring rate scaling as you move between sizes.
End coil geometry provides a flat seating surface for stable load transfer in spring seats and guide assemblies — reduces lateral buckling tendency.
Available in 1Pcs pack size so you can source exactly the quantity you need for prototyping, repair, or low-volume production without over-ordering.
| Wire Diameter | 3mm (0.118 in) |
|---|---|
| Outer Diameter (OD) | 16–25mm (0.63–0.98 in) |
| Free Length | 20–200mm (0.79–7.87 in) |
| Material | Spring Steel |
| Surface Finish | Black |
| Spring Type | Compression |
| End Type | See variant options |
| Spring Rate | See variant options |
| Max Load Capacity | See variant options |
| Pack Size | 1Pcs |
Match the outer diameter (OD) to your spring seat or bore ID with a small clearance (typically 1–2mm). Select a free length that allows sufficient compression travel while maintaining a minimum solid height margin. The 3mm wire diameter in this range suits medium-load applications — confirm the spring rate and load requirements against your design spec before ordering.
Spring rate varies by OD and free length combination. Shorter springs with smaller OD will generally have a higher spring rate; longer springs with larger OD will be softer. Exact spring rate values are not listed per variant — if your application requires a specific rate, contact us to confirm before ordering.
The black surface finish provides a baseline level of corrosion resistance suitable for dry indoor environments. These springs are not recommended for prolonged exposure to moisture, salt spray, or aggressive chemicals without additional protective measures such as coating or housing. For outdoor or wet environments, consider stainless steel alternatives.
The size format follows Wire Diameter × Outer Diameter × Free Length. For example, 3x16x20mm means: 3mm wire diameter, 16mm outer diameter, 20mm free length. Select the variant that matches all three dimensions required by your assembly.
Yes. These compression springs are compatible with guide rod assemblies where the rod diameter is smaller than the spring's inner diameter (ID = OD minus 2× wire diameter). For example, a 3x20x50mm spring has an approximate ID of 14mm, so a guide rod up to ~12–13mm diameter would be appropriate to allow free movement without binding.
The OD determines how the spring fits into a bore or onto a guide rod. A 16mm OD spring fits into a tighter bore and is suited for compact assemblies, while a 25mm OD spring provides a larger contact area and is better for applications requiring higher lateral stability or where a larger spring seat is available. Both use the same 3mm wire diameter.
Currently, these springs are listed in 1Pcs pack size. If you require larger quantities for production or bulk use, please contact us directly — we can discuss volume availability and pricing for your specific size requirements.
