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When a stamping press, injection mold, or automated fixture demands consistent return force cycle after cycle, an undersized or mismatched spring becomes the weakest link in the entire system. Engineers and toolmakers who need a heavy-load compression die spring that holds its rated deflection across thousands of cycles will find this red-coded series purpose-built for that demand.
Each spring in this series is precision-wound from high-tensile alloy steel wire and finished with a distinctive red powder coat that signals the heavy-load force class at a glance. Outer diameters span 8 mm (0.31 in) to 50 mm (1.97 in), inner diameters from 4 mm (0.16 in) to 25 mm (0.98 in), and free lengths from 15 mm (0.59 in) to 450 mm (17.72 in), covering the full range of standard die-set and tooling pocket dimensions.
Typical applications include progressive die stamping where consistent stripping force is critical, injection-mold ejector-pin return systems requiring repeatable stroke, hydraulic press safety returns, and custom automation fixtures where a compact heavy-load compression die spring must fit a defined bore and rod. The wide size matrix also makes these springs a reliable choice for maintenance engineers replacing worn springs in existing tooling without custom fabrication.
Color-coded red per ISO 10243 heavy-load designation, delivering higher spring rates than light or medium classes for demanding press and tooling applications.
OD 8–50 mm, ID 4–25 mm, free lengths 15–450 mm — a single listing covers the most common die-set pocket and guide-rod dimensions without custom orders.
Wound from high-tensile alloy steel wire with close pitch tolerances, maintaining consistent spring rate and minimizing lateral deflection under load.
Red powder-coat surface treatment provides a protective barrier against workshop moisture and light coolant exposure, extending service life in typical toolroom environments.
Designed for repetitive compression cycles; squared and ground ends ensure flat, stable seating on die plates and ejector housings for uniform load distribution.
Available in 1-piece quantities so you can replace exactly the spring you need without purchasing a full pack — ideal for maintenance and prototype tooling.
| Spring Type | Compression Die Spring |
|---|---|
| Load Class | Heavy Load (Red) |
| Standard Reference | ISO 10243 Heavy-Load Class |
| Material | High-tensile alloy steel wire |
| Surface Finish | Red powder coat |
| Outer Diameter (OD) | 8 mm – 50 mm (0.31 in – 1.97 in) |
| Inner Diameter (ID) | 4 mm – 25 mm (0.16 in – 0.98 in) |
| Free Length | 15 mm – 450 mm (0.59 in – 17.72 in) |
| End Type | Squared and ground |
| Spring Rate | See variant options |
| Maximum Deflection | See variant options |
| Quantity per Order | 1 piece |
Measure the guide-rod diameter (this becomes your minimum ID clearance), the pocket or bore diameter (this becomes your maximum OD), and the available free-length space in the open die. Choose an OD that fits the pocket with a small radial clearance, an ID that clears the guide rod by at least 0.5–1 mm per side, and a free length that allows your required working stroke without exceeding the spring's maximum deflection rating. When in doubt, consult your tooling engineer or contact us to confirm.
The red finish indicates the heavy-load force class per ISO 10243 die-spring standards. This class produces a higher spring rate than light (yellow) or medium (blue) class springs of the same size, making it suitable for applications that require strong stripping, ejection, or return forces. Always match the color class to your load calculation — substituting a lighter class can cause insufficient force, while a heavier class can overload tooling components.
The red powder-coat finish provides a protective layer suitable for typical toolroom conditions including light coolant splash and workshop humidity. For continuous immersion in aggressive cutting fluids or high-humidity environments, consider additional protective measures such as periodic re-lubrication or stainless-steel alternatives. Inspect springs regularly for surface corrosion as part of your tooling maintenance schedule.
Yes. These compression die springs are widely used in injection-mold ejector-pin return systems. Select an OD and ID that match your ejector housing pocket and guide pin, and choose a free length that provides the required return stroke with adequate preload. Verify the spring rate against your ejector plate weight and required return force to ensure reliable cycling.
Service life depends on operating deflection as a percentage of free length. Heavy-load class springs are typically rated for a defined cycle life at their recommended working deflection (commonly around 15–25% of free length for extended life). Operating beyond the recommended deflection percentage significantly reduces cycle life. Follow ISO 10243 guidelines and your tooling engineer's recommendations for deflection limits specific to your application.
Tooling maintenance often requires replacing one specific spring that has fatigued or broken, without needing a full set. Single-piece ordering lets you match the exact OD, ID, and length of the failed spring and get back into production quickly without excess inventory. For new tooling builds requiring multiple identical springs, simply increase the quantity at checkout.
Die springs are manufactured to tighter dimensional tolerances and higher load ratings than general-purpose compression springs. They follow standardized color-coded force classes (ISO 10243), have squared and ground ends for flat seating, and are designed for the repetitive high-cycle demands of stamping dies, molds, and industrial tooling. Standard compression springs are suitable for lighter-duty or less precise applications where ISO die-spring tolerances are not required.
