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2026
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Coil Spring or Nitrogen Gas Spring? Choosing the Right Mold Spring
Author:
Timould
Not sure whether to use coil springs or nitrogen gas springs in your mold? Learn how force consistency, lifespan, and cost per part differ — and which one fits your application.
What's the Difference?
Coil springs are the classic choice — cheap, simple, and available everywhere. They work fine for light, low-cycle ejection jobs.
Nitrogen gas springs use compressed gas to deliver force. They cost more up front, but they last far longer and hold consistent force throughout their entire stroke.
The Key Differences
Force consistency. A coil spring's force rises as it compresses. A gas spring delivers nearly constant force from start to finish — which means smoother, more predictable ejection.
Lifespan. Coil springs fatigue and break over time, especially at high cycle counts. Gas springs are designed for millions of cycles, with little loss in performance.
Space. Gas springs pack much higher force into a smaller size, freeing up room in the mold for cooling lines and ejector layout.
Cost. Coil springs win on price per unit. But gas springs win on cost per part over the mold's life — fewer replacements, less downtime, less scrap.
When to Choose Which
Go with coil springs for simple, low-volume molds, small ejection forces, or tight budgets.
Switch to nitrogen gas springs when you need high, consistent force, run high cycle counts, or deal with large and deep parts where even ejection force matters.
A Simple Rule
If your mold runs more than a few hundred thousand cycles, or your parts are large and heavy, gas springs almost always pay for themselves.
mold springs,gas springs,coil springs,injection molding,mold components
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