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)
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