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Engineers and toolmakers working with stamping dies, injection molds, and CNC fixtures know the frustration of springs that lose tension under repeated cycling or fail to meet dimensional tolerances. These heavy load compression die springs are built for demanding environments where consistent force output and dimensional accuracy are non-negotiable — whether you're maintaining clamp pressure in a progressive die or providing return force in an automated assembly jig.
Each spring is manufactured to JIS B 5012 heavy load (red stripe) classification, with outer diameters ranging from 8 mm (0.31 in) to 40 mm (1.57 in) and inner diameters from 4 mm (0.16 in) to 20 mm (0.79 in). Free lengths span 20 mm (0.79 in) up to 250 mm (9.84 in), giving you a wide selection matrix to match your guide pin diameter and stroke requirements precisely.
Typical use cases include die and mold spring replacement for stamping and forming tooling, stripper plate return springs in progressive dies, and compression elements in CNC workholding fixtures and robotic end-of-arm tooling — all applications where a long-tail search for "JIS heavy load die spring 20mm OD" or "red stripe compression spring for stamping die" leads engineers here.
| Spring Type | Compression Die Spring |
|---|---|
| Load Class | Heavy Load (JIS B 5012 Red) |
| Outer Diameter Range | 8 mm – 40 mm (0.31 in – 1.57 in) |
| Inner Diameter Range | 4 mm – 20 mm (0.16 in – 0.79 in) |
| Free Length Range | 20 mm – 250 mm (0.79 in – 9.84 in) |
| Material | See variant options |
| Surface Finish | See variant options |
| Spring Rate | See variant options |
| Solid Height | See variant options |
| Max Deflection | See variant options |
| End Type | Closed & Ground (typical for die springs) |
| Standard | JIS B 5012 |
Match the inner diameter (ID) to your guide pin diameter with a small clearance — typically 0.5 mm to 1 mm larger than the pin. The outer diameter (OD) must fit within the spring pocket or counterbore in your die plate. For example, if your guide pin is 9.5 mm, choose the 10 mm ID variant and confirm the OD fits your pocket. Always verify both dimensions before ordering.
JIS B 5012 classifies die springs by load color: light (yellow), medium (blue), heavy (red), and extra heavy (green). Heavy load springs have a higher spring rate — they generate more force per millimeter of deflection than light or medium grades. Choose heavy load when you need strong return force in a compact free length, or when your application requires high clamping or stripping force.
Free length should be selected so that the spring operates within 20%–30% of its maximum deflection under working load, and never exceeds the maximum deflection at solid height. Measure your available pocket depth and required stroke, then add a pre-load deflection allowance. If your stroke is 15 mm and you want 10% pre-load, a free length of approximately 50–60 mm is a common starting point for shorter-stroke applications.
Yes. These springs follow JIS B 5012 dimensional standards, which are widely compatible with standard die sets, mold bases, and guide pin systems used in stamping, forming, and injection molding tooling. Always cross-reference the OD, ID, and free length against your specific die set drawing to confirm fit before installation.
The surface treatment provides resistance to light oxidation and exposure to water-based cutting fluids and lubricants typical in die shop environments. For aggressive chemical environments or prolonged immersion, consider additional protective measures or contact us to confirm suitability for your specific conditions.
When operated within the rated deflection range (typically up to 30% of free length for heavy load grade), these springs are designed for high-cycle fatigue life consistent with JIS B 5012 standards — commonly rated for hundreds of thousands to millions of cycles depending on deflection percentage. Operating beyond the rated deflection significantly reduces fatigue life. Contact us to confirm cycle life data for your specific variant and operating conditions.
Absolutely. While die springs are named for their origin in stamping tooling, their precision dimensions, consistent force output, and compact form factor make them well-suited for CNC workholding fixtures, robotic end-of-arm tooling, pneumatic actuator return mechanisms, and any application requiring a reliable, repeatable compression spring in a standardized size envelope.
