Red-Medium Duty Load Compression Spring Die Springs O.D:8-22mm Length:20-175mm

Measure the spring pocket bore in your die plate — the spring O.D. should be 0.5 mm to 1 mm smaller than the bore for a sliding fit. For free length, add the required working stroke to the compressed (solid) height and select the next standard length above that total. Use the variant selector above to pick your O.D. × Length combination.

Per ISO 10243 and JIS B 5012, die springs are color-coded by load class: yellow = light duty, red = medium duty, blue = heavy duty, and green = extra-heavy duty. Red medium-duty springs offer a balanced spring rate suitable for blank holders, stripper plates, and ejector systems where moderate, consistent force is needed without the stiffness of heavy-duty springs.

Yes. Red-medium duty die springs are commonly used for ejector-plate return in injection molds. Select an O.D. that fits your ejector-plate spring pocket and a free length that provides adequate return stroke. Ensure the spring is not compressed beyond its rated maximum deflection (typically 30–40% of free length for medium-duty springs) to maintain service life.

These springs are made from alloy spring steel with a surface treatment suitable for dry and lightly lubricated die environments. For high-humidity or wet environments, applying a light machine oil or die lubricant to the spring surface is recommended to extend service life. They are not rated for immersion or highly corrosive chemical exposure.

Absolutely. The rectangular-wire construction provides a higher load-to-length ratio than standard round-wire coil springs, making these a compact choice for DIY CNC fixtures, workholding clamps, and automation jigs where bore space is limited. Select the O.D. and length that match your fixture pocket dimensions.

The 1-piece option is ideal for prototyping, single-die replacement, or testing a size before committing to a full set. The 5-piece pack is suited for production tooling, multi-cavity molds, or keeping spares on hand. Both options ship the same spring — only the quantity differs. The 5-piece pack offers a lower per-unit cost.

Replace a die spring when you observe: (1) visible cracking or fracture, (2) a measurable reduction in free length (set) of more than 3–5% compared to the original, (3) inconsistent press force or part quality, or (4) the spring has reached its rated cycle life. Regular inspection during die maintenance is recommended.