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Engineers and toolmakers working with stamping dies, injection molds, and progressive tooling know the frustration of springs that fatigue prematurely or deflect inconsistently under cyclic load. These die springs compression springs are engineered for medium load duty applications where reliable, repeatable force is non-negotiable — whether you are building a new die set or replacing worn-out springs in an existing press tool.
Each spring is manufactured from manganese steel (65Mn), a spring-grade alloy known for its high tensile strength and fatigue resistance. Outer diameters span 8 mm to 50 mm (approximately 0.31 in to 1.97 in), inner diameters from 4 mm to 25 mm (approx. 0.16 in to 0.98 in), and free lengths from 15 mm to 350 mm (approx. 0.59 in to 13.78 in). The consistent coil pitch and ground ends ensure stable seating and uniform load distribution across the full compression stroke.
Typical use cases include stamping die cushioning and stripping, injection mold ejector plate return, fixture clamping and workholding, and general industrial machinery where a compact, high-cycle compression spring is required. Long-tail search terms such as "medium load die spring 8mm OD", "65Mn compression spring for stamping die", and "manganese steel coil spring tooling" describe exactly what this product delivers.
| Material | 65Mn Manganese Steel |
|---|---|
| Load Type | Medium Load Duty |
| 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 – 350 mm (0.59 in – 13.78 in) |
| End Type | Closed & Ground |
| Coil Direction | Right-hand (standard) |
| Surface Finish | See variant options |
| Quantity per Order | 1 Piece (per variant selected) |
| Application | Stamping dies, injection molds, industrial fixtures, press tooling |
Measure the bore diameter of your die spring pocket — this determines the maximum outer diameter (OD) you can use. Then measure your guide pin or mandrel diameter — this must be smaller than the spring's inner diameter (ID) to allow free movement. As a general rule, allow 0.5 mm to 1 mm clearance on each side. Select the OD and ID combination from the variant options that best matches your pocket and pin dimensions.
Die springs are typically classified by load rating — light, medium, heavy, and extra-heavy — which corresponds to the spring's wire diameter relative to its OD and the resulting spring rate (force per unit deflection). Medium load duty springs offer a moderate spring rate suitable for stripping, ejection, and cushioning operations where light-duty springs would bottom out too easily but heavy-duty springs would require excessive press force. They are the most commonly specified grade for general-purpose tooling.
Medium load die springs are typically rated for a maximum deflection of approximately 25–35% of their free length before reaching solid height. Exceeding this range accelerates fatigue and reduces service life. For continuous cycling applications, operating at 20–25% deflection is recommended to maximize longevity. Refer to your specific free length variant and calculate the working stroke accordingly.
These springs are manufactured to dimensions consistent with common die spring standards used in stamping and mold tooling. However, if your application requires springs certified to a specific ISO 10243 or JIS B 5012 tolerance class, please contact us to confirm compliance before ordering, as dimensional tolerances may vary by size.
65Mn manganese steel has moderate corrosion resistance. The surface finish applied during manufacturing provides a degree of protection against oxidation in normal indoor workshop conditions. For applications involving exposure to coolants, cutting fluids, or high humidity, consider applying a light coat of oil or grease to the spring surface, or contact us to inquire about alternative finish options.
Yes. Medium load die springs are widely used in injection mold ejector plate return systems. Select an OD that fits your spring pocket, an ID that clears your ejector guide pin, and a free length that provides the required ejector stroke plus adequate preload. Ensure the spring does not reach solid height during the ejection stroke to avoid impact loading and premature failure.
The required free length depends on your working stroke and desired preload. A common approach: Free Length = Working Stroke ÷ Maximum Deflection Ratio + any preload compression. For medium load springs, use a maximum deflection ratio of 0.25–0.30. If you need help sizing, contact us with your stroke, pocket depth, and load requirements.
