Spring

An human-friendly guide to Delta Robotics’ Nitinol Tension Springs — covering specs, control, cooling, and how not to accidentally cook your actuator.

Nitinol Tension Springs: Tiny Coils with Big Pull

At Delta Robotics, we don't just sell wire — we also sell wire that’s been coiled into little powerhouses. Meet our Nitinol Tension Springs, precision-formed from shape memory alloy, ready to yank, lift, and contract with muscle-like motion. They’re like the wire’s gym-rat cousin: more compact, still ripped.

This page walks you through what they are, how they work, and how to keep them springing instead of snapping.


📦 What’s in the Coil (Product Overview)

Here’s what you’re getting:

  • Material: Shape Memory Alloy (Nitinol)

  • Form: Precision tension spring, trained to contract when heated

  • Actuation Method: Joule heating (yep — just run current through it)

  • Length: 50mm

  • Spring ODs: 5 mm, 10 mm, 20 mm

  • Wire Diameters: 0.5 mm, 1.0 mm, 2.0 mm

  • Activation Temp: ~90 °C (like a hot cup of tea, but way more useful)

  • Mounting: Each spring comes pre-mounted with 5052 aluminum fixtures on both ends — electrically conductive, mechanically overbuilt, and ready to plug into your project

These aren’t passive mechanical springs — they’re active, electrically actuated devices.


🧪 Spring Stats (By Size)

Spec

0.5 mm Spring

1.0 mm Spring

2.0 mm Spring

Wire Diameter

0.5 mm

1.0 mm

2.0 mm

Outer Diameter

5 mm

10 mm

20 mm

Max Force (Estimated)

2–3 N

8–10 N

25–30 N

Stroke Length (Est.)

15–20 mm

30–40 mm

40–50 mm

Resistance (Ω)

0.79 Ω

0.41 Ω

0.17 Ω

Contraction Current

4 A

16 A

60 A

Actuation Power

12 W

105 W

600 W

Cooling Time (Air)

5–15 s

20–30 s

60 s

Cooling Time (Fan)

2–6 s

8–15 s

20–30 s

Cooling Time (Water)

1 s

2–3 s

5–7 s

Efficiency

2–5%

2–5%

2–5%

Cycle Life (at 3–5%)

100,000–1,000,000

100,000–1,000,000

100,000–1,000,000

Operating Temp Range

0 °C – 120 °C

0 °C – 120 °C

0 °C – 120 °C

⚠️ We’re still validating these values, so don't take them at face value. Spot something weird — let us know!


🔄 How Long Will It Bounce Back?

Spring fatigue is real — but manageable. Stay within the strain limits, and these springs can run laps for months:

Strain

Cycle Life

2%

1,000,000+ cycles

4%

100,000+ cycles

6%

10,000–20,000 cycles

8%

2,000–5,000 cycles

>8%

💀 Umm like maybe a few.

Pro tip: Springs tend to settle in. Run a few warmup cycles to stabilize force output.


🧠 How to Control It (Like a Spring Whisperer)

Just like our wire, these springs love the ThermoFlex™ Node Controller:

  • 60 A output — enough to boss around 2 mm springs

  • USB & CAN control for scripting and sync

  • Built-in current sensing for over-temp protection

  • Works with custom ramp profiles for smooth motion


❄️ Cooling It Down (100% Faster Than Watching Paint Dry - we tested it.)

Like all shape memory alloys, these springs can only cycle as fast as they can cool:

  • Air Cooling: 5–60 s depending on spring size

  • Fan Cooling: Much better — think 2× to 5× faster

  • Water Cooling: Instant noodle fast — 1–7 s depending on size

We’re working on integrated cooling gear. Until then, BYOF (bring your own fan).


🔧 Mounting Tips (From People Who've Broken Stuff)

These aren’t passive springs — they fight back. Mount them accordingly:

Physical Mounting

  • Comes with pre-installed 5052 aluminum mounts — no additional brackets, no fuss

  • Seriously, just bolt it in and go

Electrical Connection

  • Aluminum mounts are conductive — clamp them or screw them into your terminals

  • Soldering is possible but tricky. The large surface area of the aluminum spring mount makes it hard to get the solder to the right temp.


Best Practices

  • ✅ Pre-tension the spring slightly for faster response

  • ✅ Use mechanical mounting over adhesives

  • ✅ Stay under 5% strain for high cycle life

  • 🚫 Don’t overheat — target 90 °C, not lava

  • 🚫 Don’t cut your spring unless you know what you’re doing (ask us, we'll tell you)


Last updated

Was this helpful?