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When a worn or undersized spring causes mold flash, misalignment, or premature tool failure, the cost goes far beyond the part itself. Engineers, toolmakers, and serious hobbyists who work with injection molds, stamping dies, and precision fixtures need compression springs they can spec with confidence — not guess at. These heavy-duty compression mold springs are engineered to deliver consistent, repeatable force across a wide range of bore and length combinations.
Each spring is manufactured from high-carbon spring steel wire, finished with a close-wound, ground-end construction for stable seating. Outer diameters span 6 mm to 30 mm (approximately 0.24 in to 1.18 in), inner diameters from 3 mm to 20 mm (approximately 0.12 in to 0.79 in), and free lengths from 15 mm up to 200 mm (approximately 0.59 in to 7.87 in). Bearing weight ratings range from 3.3 KG to 48 KG depending on the selected variant.
Typical use cases include injection mold ejector-pin return systems, progressive die stripper plates, jig and fixture clamping mechanisms, and custom automation tooling where a specific spring rate and travel must be maintained over thousands of cycles.
OD 6–30 mm × ID 3–20 mm with lengths from 15 mm to 200 mm — one listing covers the most common mold spring pocket sizes.
Each variant carries a published bearing weight from 3.3 KG to 48 KG, so you can match spring force to your ejection or clamping requirement without guesswork.
Flat-ground ends provide a stable, perpendicular seating surface that reduces lateral deflection and uneven load distribution in tight pockets.
Spring steel construction maintains consistent spring rate across repeated compression cycles — resisting set and fatigue in continuous-duty tooling environments.
Dimensional tolerances follow standard mold spring conventions, making these a straightforward swap for worn or broken springs in existing tooling without pocket modification.
Order exactly the quantity you need — no forced multi-packs. Select your outer diameter × inner diameter, length, and bearing weight from the variant options above.
| Spring Type | Compression Mold Spring |
|---|---|
| Material | High-carbon spring steel |
| End Type | Close-wound, ground ends |
| Outer Diameter (OD) | 6 mm – 30 mm (0.24 in – 1.18 in) |
| Inner Diameter (ID) | 3 mm – 20 mm (0.12 in – 0.79 in) |
| Free Length | 15 mm – 200 mm (0.59 in – 7.87 in) |
| Bearing Weight | 3.3 KG – 48 KG (varies by variant) |
| Surface Finish | See variant options |
| Wire Diameter | See variant options |
| Spring Rate | See variant options |
| Quantity per Order | 1 piece |
The outer diameter (OD) should be slightly smaller than your mold pocket bore to allow free movement without binding. The inner diameter (ID) should be slightly larger than your guide pin diameter — typically 0.2–0.5 mm clearance on each side. Check your tool drawing for pocket and pin dimensions before selecting a variant.
Bearing weight refers to the rated load capacity of the spring at a specified compression. It indicates the force the spring can reliably exert without permanent deformation. Match this to your required ejection or clamping force. If your application requires a specific spring rate (N/mm), contact us to confirm before ordering.
Yes. These compression mold springs are designed for exactly this application. Select the OD and ID that fit your ejector plate pocket and guide pin, then choose a free length that provides adequate pre-load and travel within your mold's open/close stroke.
The springs are manufactured from high-carbon spring steel. For environments with coolant exposure or humidity, consider applying a light machine oil coating during installation. If your application requires stainless steel or a specific corrosion-resistant finish, contact us to confirm availability before ordering.
Yes. These springs are commonly used in stripper plate and blank holder applications in stamping and progressive die tooling. Verify that the selected bearing weight and free length match your die's required stripping force and stroke. For high-cycle stamping (over 500,000 cycles), inspect springs regularly for fatigue set.
Free length is the spring's natural, unloaded length — the dimension listed in the variant options. Compressed length (solid height) is the minimum length when fully compressed coil-to-coil. Your application's working stroke must stay within the range between pre-loaded length and solid height to avoid over-compression and permanent set. If you need solid height data for a specific variant, contact us to confirm.
Each order is for one (1) spring. If you need multiple springs for a multi-cavity mold or a full ejector plate, simply set the quantity in your cart to match your requirement.
