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When a standard spring simply won't hold up under repeated cycling loads, engineers and serious makers reach for heavy load compression die springs. Whether you're building a press tool, a fixture jig, or a mechanical assembly that demands consistent return force, these ISO-rated springs deliver the controlled deflection and fatigue resistance your project requires — without the guesswork of undersized components.
Each spring in this range features a cylindrical coil body wound from high-grade spring steel wire, finished with a colour-coded powder coat that indicates load class at a glance. Outside diameters span 27 mm (~1.06 in) and 30 mm (~1.18 in), with inside diameters of 13.5 mm (~0.53 in) and 15 mm (~0.59 in) respectively. Lengths run from 25 mm (~0.98 in) up to 300 mm (~11.81 in), giving you a wide selection for both compact and extended-travel applications.
Typical use cases include die and mould tooling (compression die spring replacement), industrial press fixtures requiring repeatable spring-back force, and custom mechanical assemblies such as valve actuators, clamp returns, and robotic end-effectors where a heavy load compression spring with precise ISO deflection characteristics is specified.
Available in Yellow, Blue, Red, Green, and Brown finishes — each indicating a distinct load rating for fast visual identification in multi-spring tooling setups.
Wound and finished to ISO heavy load specifications, ensuring consistent spring rate, deflection limits, and interchangeability with other ISO-compliant die spring systems.
Outside diameters of 27 mm (ID 13.5 mm) and 30 mm (ID 15 mm) cover the most common die spring pocket sizes in standard tooling plates and press fixtures.
Free lengths from 25 mm to 300 mm let you match stroke requirements precisely — from short-travel clamp returns to long-travel ejector pin assemblies.
Spring steel construction with surface treatment supports extended service life under repeated compression cycles, reducing downtime from spring fatigue failure in production tooling.
Standardised OD, ID, and free-length dimensions allow direct substitution in existing die sets without modification to the tooling pocket or guide pin.
| Standard | ISO 10243 Heavy Load |
|---|---|
| Outside Diameter | 27 mm (1.06 in) / 30 mm (1.18 in) |
| Inside Diameter | 13.5 mm (0.53 in) / 15 mm (0.59 in) |
| Free Length Range | 25 mm – 300 mm (0.98 in – 11.81 in) |
| Load Class | Heavy Load |
| Available Colours | Yellow, Blue, Red, Green, Brown |
| Material | Spring Steel (high-carbon alloy) |
| Surface Finish | Colour-coded powder coat |
| End Type | Closed & ground ends |
| Max Deflection | See variant options |
| Spring Rate | See variant options |
| Operating Temperature | See variant options |
Select a free length that gives you the required working stroke plus a safety margin. ISO heavy load die springs are typically rated for deflection up to 30–40% of free length. For example, if you need 30 mm of travel, a 100 mm free length spring provides comfortable operating range. Always confirm the maximum deflection specification for your chosen variant before finalising your design.
The colour identifies the load class within the ISO 10243 die spring system. In this listing, all springs are Heavy Load rated. The colour variants (Yellow, Blue, Red, Green, Brown) are offered as finish options within the heavy load class — useful for colour-coding different spring positions in a multi-cavity tool for quick visual identification during maintenance.
The 27 mm OD spring has an inside diameter of 13.5 mm and fits tooling pockets bored to 27 mm. The 30 mm OD spring has an inside diameter of 15 mm and fits 30 mm pockets. Both are heavy load class but will have different spring rates due to the difference in wire diameter and coil geometry. Choose based on your existing pocket size and the load requirement of your application.
The powder coat finish provides a degree of surface protection against light moisture and handling. However, these springs are designed primarily for dry tooling environments. For applications involving coolant, cutting fluid, or high-humidity conditions, consider additional protective measures or consult the specification sheet for your chosen variant to confirm suitability.
Yes — provided the OD, ID, and free length match your existing spring. ISO 10243 heavy load springs are standardised, so these are designed as drop-in replacements for worn or fatigued springs in compatible die sets. Always verify the spring rate and maximum deflection of the replacement matches the original specification to maintain tooling performance.
ISO heavy load die springs are engineered for extended fatigue life. Cycle life depends on the operating deflection as a percentage of free length — operating at lower deflection percentages significantly extends service life. For production tooling, it is common practice to replace springs at scheduled intervals rather than waiting for failure. Refer to the ISO 10243 standard or the variant datasheet for specific cycle life curves.
For the 27 mm OD spring (ID 13.5 mm), a guide pin of approximately 12–13 mm diameter is typical, leaving a small clearance to prevent binding. For the 30 mm OD spring (ID 15 mm), a guide pin of approximately 13–14 mm is recommended. Always allow at least 0.5 mm radial clearance between the guide pin and the spring ID to avoid friction-induced fatigue.
