“Please quote 0.5 mm nitinol wire” looks clear, but it leaves most of the functional specification unanswered. Nitinol wire can be superelastic at room temperature, thermally activated, cold drawn for customer processing, straight annealed for immediate use, polished for a downstream surface route, or supplied with oxide from drawing. Two wires with the same diameter and chemistry can behave differently because of cold work, heat treatment, transformation temperature, and final geometry.
A useful RFQ tells the supplier what the wire must do, how it will be processed, and how acceptance will be measured. GEE SMA's nitinol wire capability covers superelastic and shape memory families, multiple alloy codes, cold-drawn and straight-annealed conditions, surface options, and material testing. The eight decisions below turn that range into an orderable product.
Decision 1: Define the Functional Behavior
Start with superelastic recovery, thermal shape recovery, actuator contraction, kink resistance, spring force, or customer shape setting. Do not use “shape memory” as a catch-all description for every NiTi behavior. A superelastic component usually operates above its transformation range and recovers after unloading; a shape memory component is deformed in martensite and recovers when heated.
The application should also state the operating temperature, load mode, target strain, and expected life. A one-time deployment wire, an orthodontic raw material, a fishing leader, and a million-cycle actuator do not share one acceptance plan. GEE SMA's behavior and Af selection controls keep the performance request connected to the phase transformation that creates it.
Decision 2: Select an Alloy Family
GEE SMA product notes list SE510, SE508, SE508 ELI, LSE5065, LSE507 ELI, and low-temperature NiTiCr among superelastic wire options. Shape memory options include titanium-rich binary grades and Copper NiTi. Each family occupies a different transformation and mechanical window. Medical relevance, inclusion control, plateau feel, low-temperature recovery, narrow hysteresis, and actuator temperature can all influence the choice.
If the engineering team does not know the alloy code, provide the required behavior and ask for two or three candidate samples. Avoid specifying SE508 only because it is familiar. GEE SMA's NiTi alloy and product range supports a comparison based on the application rather than on naming habit.
Decision 3: Set Transformation Temperature and Test Temperature
Transformation temperature determines whether the wire is martensitic, austenitic, or inside the transition range during use. For superelastic wire, Active Af should normally sit below the intended operating temperature by a suitable margin. For shape memory wire, Active Af becomes part of the thermal trigger. Copper NiTi may be considered when narrow hysteresis or a particular activation window matters.
The RFQ must also state the temperature at which mechanical properties are tested. ASTM F2516 reports superelastic tensile behavior at the test temperature, so a result at room temperature cannot silently represent a hotter or colder use case. GEE SMA's test-temperature specification approach makes this often-missed variable visible to purchasing and quality teams.
Decision 4: Choose the Delivery Condition
Cold-drawn wire retains cold work and can show cast and twist. It is often selected when the customer plans additional straightening, forming, coiling, grinding, or heat setting. Straight-annealed superelastic wire has received a heat treatment intended to provide straightness and functional recovery in the delivered form. Actuator-ready or trained shape memory wire follows another processing route.
The correct condition depends on who owns the final heat treatment. If both supplier and customer heat treat without a shared process plan, transformation behavior can drift. GEE SMA's forming and shape-setting capability is relevant when the boundary between raw wire and finished component needs to be defined.
Decision 5: Dimension More Than Diameter
Diameter and tolerance are the beginning, not the end. Straightness, cast, twist, ovality, length, spool core, traverse, and cut-end condition can affect automatic feeding, grinding, braiding, forming, and inspection. GEE SMA product notes list wire from 0.05 mm [0.002 in.] and up for several product families, but the practical tolerance and delivery format depend on alloy, condition, and size.
Explain what happens next. A spool used in continuous processing needs controlled presentation and labeling. Straight cut lengths need length tolerance, straightness, and protective packaging. GEE SMA's diameter and supplier controls help link dimensional acceptance to the actual downstream operation.
Decision 6: Specify Surface and Visual Quality
Available descriptions may include black oxide, light oxide, mechanically polished, centerless ground, or a customer-defined surface route. These terms influence appearance and processing, but they should not replace measurable visual or roughness requirements when surface is critical. Scratches, seams, pits, debris, discoloration, and handling marks can affect coating, joining, corrosion evaluation, and fatigue.
The buyer should state whether the received surface is final or will be ground, etched, electropolished, coated, or cleaned again. Medical-device programs must evaluate the final manufactured surface rather than relying only on incoming wire condition. GEE SMA's surface and passivation controls support this separation between mill finish and final component finish.
Decision 7: Match Tests and Documents to the Risk
A certificate can include chemistry, alloy code, dimensional results, tensile properties, superelastic plateau values, residual elongation, Active Af, DSC data, lot number, and surface or visual inspection. ASTM F2516 is relevant to superelastic tensile response. ASTM F2082/F2082M may be used for bend-and-free-recovery transformation testing. ASTM F2063 applies to defined wrought medical NiTi material within its scope and does not make a finished device compliant by itself.
Ask for the data that controls the application, and identify the sample condition used for testing. An overloaded certificate with unrelated numbers can still miss the one test temperature or Active Af value that matters. GEE SMA's ASTM material-control capability is useful when documentation must be tied to lot, condition, and downstream responsibility.
Decision 8: Define Packaging and Change Control
Wire can be damaged after final inspection. Spool tension, crossovers, loose ends, abrasion, moisture, incorrect core size, and poor carton support can create feeding and surface problems. GEE SMA product notes describe spool and export-carton packaging, protective paper around reels, and stronger outer packaging for larger shipments. The RFQ should define spool material, core size, maximum spool weight, end restraint, protective wrap, and label content when these factors affect production.
Change control belongs in the same discussion. Alloy source, melting route, heat treatment, drawing practice, surface process, spool supplier, and test method can influence qualification. GEE SMA's supplier evaluation and process control matter when a prototype wire must transition into stable production without undocumented changes.
A Compact RFQ Data Set
- Application, operating temperature, load mode, working strain, and cycle target.
- Alloy code or candidate comparison, Active Af, and required test temperature.
- Delivery condition and ownership of forming, shape setting, and final heat treatment.
- Diameter, tolerance, straightness, cast, twist, spool, cut length, and end condition.
- Surface finish, visual acceptance, cleanliness, and all downstream finishing steps.
- Required certificate data, standards, sampling, lot traceability, packaging, and change notification.
A complete nitinol wire RFQ does not need to be long, but it must connect material behavior to manufacturing reality. When function, alloy, transformation temperature, condition, dimensions, surface, tests, and packaging are all defined, the quotation becomes comparable, prototypes become more informative, and production qualification starts from a stable baseline.