Die Spring Calculator

What this calculator does

Die springs, also called mould springs, use rectangular wire, which packs more energy into a given envelope than round wire. The allowable compression is limited — typically 15–25% of free length for long life — so the calculator reports the load at the recommended compression ratio as well as at full stroke.

Inputs and outputs

Inputs

Outside diameter and inner diameter
Free length
Wire cross-section
Load class: light, medium, heavy or extra heavy
Required stroke
Material and colour class

Results

Spring rate and load at stroke
Compression ratio
Stress compared with the allowable
Recommended maximum compression
Expected service-life band

Typical applications

Stamping dies
Injection moulds
Die-casting dies
Fixtures and clamps
Automation equipment

Design notes

Never compress a die spring to solid. Choose the lightest load class that meets the requirement so the spring runs below its fatigue limit, and guide the spring on a mandrel when stroke rates are high.

The interactive calculator interface is currently in Chinese. Enter your values there, or send us the load, travel and space constraints and our engineers will return a checked calculation sheet in English.

Frequently asked questions

What compression ratio should I use?

For long service life, keep die springs at or below about 15% of free length. Medium and heavy classes allow more compression but at the cost of fatigue life; the calculator shows the trade-off.

Are colour classes standard?

Colour coding follows the common ISO die-spring convention: light, medium, heavy and extra heavy. Confirm the load class on the supplier datasheet because colours are not fully interchangeable between brands.

Can you match a brand part number?

Yes. Send the original brand and part number and we will cross-reference the dimensions, load class and free length before quoting.