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Nitinol · NiTi Shape Memory

Shape memory.
Superelastic.
Biocompatible.

Nitinol (nickel-titanium 50/50) exhibits shape memory effect and superelasticity — unique metallurgical properties enabling medical stents, dental archwires, actuators, and self-deploying aerospace structures. FDA-approved for implantable medical devices.

01 · Grades & variants

Nitinol compositions.

Small composition changes dramatically alter transformation temperature and properties. Medical grade, actuator grade, and superelastic grade optimize different behaviors.

Superelastic

Af < body temp

Austenitic at body temperature — exhibits superelasticity. Used for stents, guidewires, dental archwires that recover shape.

Shape Memory

Thermal trigger

Martensitic at room temp, transforms at specific heat. Used for thermal actuators, deployment mechanisms.

Body-Temperature SMA

Af ~ 30-35 °C

Transforms near body temperature. Used for orthodontic archwires that adjust their shape with oral temperature.

Actuator Grade

High force output

Optimized for repeatable cycling under mechanical load. Used for precision actuators, aerospace deployment.

Medical Grade

ASTM F2063

Medical implant grade. FDA certified. Tight composition control for biocompatibility. Used for cardiovascular stents, orthopedic devices.

Non-Magnetic

MRI compatible

Certified non-magnetic for MRI safety in medical implants.

02 · Why this material

Unique Nitinol properties.

No other material combines superelasticity, biocompatibility, and programmable shape change.

Superelastic up to 8% strain

Conventional metals: 0.1-0.5% elastic strain before permanent deformation. Nitinol: 8% strain fully recoverable. Enables flexibility in medical devices.

Shape memory effect

"Remembers" programmed shape — deform cold, heat triggers return to memorized shape. Used for thermal actuators, self-deploying structures.

Biocompatibility

FDA-approved for implantable medical devices. Non-toxic nickel release, excellent corrosion resistance in body fluids.

Fatigue resistant

Can cycle millions of superelastic cycles — dental archwires last years under cyclic loading.

03 · Applications

Nitinol applications.

Cardiovascular stents

Self-expanding vascular stents — crimped for delivery, expand to permanent shape at body temperature

Surgical guidewires

Flexible guidewires for catheterization — navigate torturous vasculature, recover shape

Dental archwires

Orthodontic archwires that apply constant corrective force as teeth move

Orthopedic staples

Shape-memory staples that close bone fractures when warmed to body temperature

Eyeglass frames

Flexible eyeglass frames that recover shape after bending

Aerospace actuators

Self-deploying mechanisms in spacecraft — thermal trigger replaces mechanical/explosive actuators

Thermal actuators

Industrial thermostat actuators — simpler than bimetallic designs

Firefighter hardware

Temperature-activated fire sprinkler components

Basket retrieval devices

Flexible surgical retrieval devices — collapse for delivery, expand for use

04 · Finishing

Nitinol processing.

Machined

Difficult but possible. Sharp carbide, slow speeds, specialized techniques. Often combined with EDM.

Wire EDM

Preferred for complex 2D features in Nitinol sheet. Fine features, no heat damage.

Laser cut

Standard for Nitinol stent tubes — precision strut patterns cut directly from tubing.

Shape set

Critical step: program memorized shape by heating to 500 °C in fixture. Defines the shape it "remembers."

Electropolished

Required for medical devices — smooth surface, reduced nickel release, enhanced corrosion resistance.

Oxide removed

Surface oxide layer cleaned after processing — standard for medical applications.

Passivated

Bright-dip acid passivation to standardize surface condition.

Cannot weld

Conventional welding disrupts nitinol phase transformation. Specialty laser welding possible with careful technique.

FAQ

Nitinol questions.

Shape memory: material deformed cold remains deformed; heating above transformation temperature causes return to memorized shape. One-way effect. Superelasticity: material is above transformation temperature in service; loading causes reversible phase transformation; unloading returns to original shape immediately without heat input. For medical stents deploying at body temperature, superelasticity is the relevant behavior. For thermal actuators, shape memory.
Nitinol raw material: $300-600/kg for medical grade, $150-300/kg for industrial. Premium reflects: (1) precise composition control required (50/50 Ni-Ti with ±0.1% tolerance), (2) specialty processing, (3) limited global production. Machining cost: 5-10× equivalent stainless due to difficulty. Medical-grade finished part: often $500-2000 per small stent or guidewire. Cost justified by enabling applications no other material supports.
ASTM F2063 standard for implantable Nitinol. Composition control, surface finish requirements, nickel release testing. Medical devices require: electropolishing for smooth surface, oxide removal, bioburden control, documentation chain from raw material to finished implant. FDA 510(k) approval depends on following established manufacturing practices.
Nitinol work-hardens during cutting — work hardens from cold-worked to harder condition during machining. Tools wear rapidly. Preferred approach: laser cutting for 2D features in sheet/tube, wire EDM for internal features, CNC only for simple external features. For CNC: sharp carbide tooling, slow speeds (20-40 m/min), continuous cutting without dwell, flood coolant. Plan significantly longer cycle times.
Critical to Nitinol function. Process: fixture part in desired memorized shape, heat to 450-550 °C for 5-15 minutes, cool. This sets the "memorized" shape. Must be done after all machining and forming — changes to the part after shape setting won't be remembered. Requires specialized fixturing and precise temperature control. Our shape-setting capability supports both prototype and production Nitinol parts.
Medical-grade Nitinol: 4-8 weeks material lead time (limited suppliers, small batches). Industrial: 3-4 weeks. Wire EDM: 1-2 weeks additional. Laser cutting: 1-2 weeks. Shape setting: 1-2 days. Electropolish and finishing: 1-2 weeks. Total medical Nitinol project: 8-16 weeks typical. Industrial Nitinol: 6-8 weeks.
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