ISO Die Springs.

What are ISO Die Springs?

ISO die springs, often called metric die springs, are high-load compression springs produced to ISO dimensional tolerances for repeatable force and a precise fit.

They are built for continuous cycling in tooling and machinery where space is limited, but dependable energy storage and return are essential. For example, in press tools and injection moulding, they keep mechanisms moving smoothly by delivering consistent push-back and reducing unplanned stops.

How ISO Die Springs Work

During operation, the spring compresses to store energy and then returns to its free length, providing a steady, predictable force on every stroke. ISO tolerances keep outer diameter and free length uniform from batch to batch, so ISO die springs drop neatly into standard pocket sizes and make maintenance straightforward.

Strength classes, from light through to extra heavy duty, let you balance force and travel for the task at hand: lighter classes accommodate longer working strokes and more delicate components, while heavier classes deliver higher forces over shorter strokes. (Note: ISO ranges do not include an Extra Light class like their counterpart JIS die springs.) The outcome is reliable performance across press tooling, injection moulds and heavy cycle equipment.

Materials ISO Die Springs Are Made From

Our ISO die springs are made from steel, selected for high compressive strength and fatigue resistance under repeated loading, supporting stable performance and dimensional integrity in demanding industrial environments.

Sizes and Types of ISO Die Springs Available

Accu supplies ISO metric die springs in the following sizes and strength classes to help you match pocket size and required force:

• Outer Diameter (OD): 10 mm to 63 mm
• Free Length: 25 mm to 305 mm
• Strength Classification: Light, Medium, Heavy, Extra Heavy

These options simplify selection for a wide range of layouts, forces and duty cycles.

FAQs

Q: What do the colours mean on ISO die springs?

A: Colour markings indicate the strength classification (Light to Extra Heavy), helping technicians confirm spec during maintenance changeovers. For exact colour mapping, please check our colour chart guide for die springs.

Q: What makes ISO die springs different from standard compression springs?

A: They are produced to ISO manufacturing tolerances for outer diameter and free length, giving a consistent fit in standardised spring pockets and predictable force–deflection behaviour across batches.

Q: How do I choose between Light, Medium, Heavy and Extra Heavy?

A: Start with the available envelope (OD and free length) and your working deflection. Select the class that achieves the target force within the recommended travel. Lighter classes suit longer strokes; heavier classes deliver higher force over shorter strokes.

Q: Do ISO die springs suit high-cycle tooling?

A: Yes, provided they are operated within the working deflection recommended for the chosen class and installed square to minimise side-loading.

Q: What measurements do I need to replace an existing ISO die spring?

A: Measure outer diameter and free length with the spring removed and unloaded, then identify the strength class (often by colour or part code) and match those parameters.

Bespoke ISO Die Springs Manufacture.

High precision, bespoke manufacture of ISO Die Springs to customer specification. State of the art facilities specialising in both small batch prototyping and large scale manufacture.