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When your project demands consistent spring force in a compact footprint, finding the right compression spring can be frustrating. Hobbyists, electronics engineers, and precision DIY makers often struggle with springs that are too stiff, too loose, or simply the wrong size. These compression springs are engineered for exact-fit applications where wire diameter, outer diameter, and free length all matter.
Each spring is wound from carbon steel wire with a uniform helical coil structure. Wire diameters range from 0.2 mm to 0.4 mm (approximately 0.008–0.016 in), outer diameters span 1.5 mm to 12 mm (approximately 0.06–0.47 in), and free lengths cover 5 mm to 305 mm (approximately 0.2–12 in). Springs are sold in packs of 10 pieces per variant.
These compression springs are well-suited for miniature electronics assemblies requiring button or contact preload, robotics and automation mechanisms needing return-force elements, and precision instrument or sensor housings where space is limited. Long-tail use cases include small compression spring for PCB contact, micro coil spring for pen clicker mechanism, and miniature return spring for sensor actuator.
| Spring Type | Compression (helical coil) |
|---|---|
| Wire Diameter Range | 0.2 mm / 0.3 mm / 0.4 mm (0.008–0.016 in) |
| Outer Diameter Range | 1.5 mm – 12 mm (0.06–0.47 in) |
| Free Length Range | 5 mm – 305 mm (0.2–12.0 in) |
| Material | Carbon steel |
| Coil Direction | See variant options |
| End Type | See variant options |
| Surface Finish | See variant options |
| Spring Rate | See variant options |
| Pack Quantity | 10 pcs per pack |
Wire diameter directly affects spring stiffness (spring rate). A thicker wire (0.4 mm) produces a stiffer spring with higher load capacity, while a thinner wire (0.2 mm) yields a softer spring suited for light-touch contacts or delicate mechanisms. Match wire diameter to your required load and deflection range. If you are unsure, start with 0.3 mm as a mid-range option.
Wire diameter (0.2–0.4 mm) refers to the thickness of the steel wire used to wind the coil. Outer diameter (OD, 1.5–12 mm) is the overall width of the spring coil from outside edge to outside edge. When fitting a spring into a bore or housing, the OD must be smaller than the bore inner diameter. When fitting over a shaft or pin, the spring inner diameter (OD minus 2× wire dia) must be larger than the shaft.
These springs are made from carbon steel, which offers good mechanical properties but limited inherent corrosion resistance. For indoor, dry, or low-humidity environments they perform reliably. For applications exposed to moisture, chemicals, or outdoor conditions, consider applying a light coating of machine oil or contact us to confirm whether a coated or stainless variant is available for your size.
Yes. The small wire diameters (0.2–0.4 mm) and compact outer diameters (as small as 1.5 mm OD) make these springs well-suited for PCB contact pads, battery terminals, push-button mechanisms, and connector preload applications. Verify that the spring's free length and compressed length fit within your PCB stack height before ordering.
Free length is the uncompressed length of the spring. To select correctly: (1) measure the available travel distance in your assembly, (2) determine how much compression you need under load, and (3) choose a free length that is longer than your compressed target by your required travel. For example, if you need 10 mm of travel and want the spring compressed to 15 mm, select a free length of approximately 25 mm.
All variants are sold in packs of 10 identical springs. Each listing specifies the wire diameter, outer diameter, and free length. Select the combination that matches your requirement from the variant dropdowns above, then add to cart. Bulk quantities beyond 10 pcs can be achieved by ordering multiple packs.
Common applications include: pen clicker return mechanisms, miniature valve springs, sensor actuator return springs, battery contact preload springs, robotics joint return elements, instrument panel button springs, and small mechanical assembly preload components. The wide size range (OD 1.5–12 mm, length 5–305 mm) covers most small-to-medium precision mechanical needs.
