Hysteresis Graph (fig. B)
Date: Feb. 28, 2005
Description: 016 SE Niti
Test Temp: 37° C
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PLEASE MAKE A SELECTION:
G&H® Wire Co. is a recognized leader in manufacturing Nickel Titanium wire products. Continuous and meticulous testing of our wires insure the high standards of performance we guarantee. State-of-the-art stress/strain testing of Nickel Titanium wire is performed employing a three-point deflection test (fig. A) with a load cell probe impacting a wire and recording the forces throughout the range from deflection to recovery. The test data (force vs. deflection) must validate that each production batch meets our stringent specifications and then is documented and archived on a hysteresis graph (fig. B) for each production batch we manufacture.
How a Hysteresis Graph demonstrates if a Niti wire will fullfill the clinical expectations of elasticity, consistent force and shape memory.
- Start test – Load cell contacts wire and begins deflection in 37°c waterbath
- Extreme elasticity shown by the Load Resistance Force (bump in the graph) at 0.6mm deflection
•This wire is active and aggressive as it transitions from the Austenitic (increasing force) to Martensitic (constant force) state
- Consistent forces of Martensitic response
•Engagement forces have "flatlined" at 230g as the wire is deflected from 0.6mm to 2.0mm
•Desired, defined excursion of Martensitic phenomenon (constant force over a large deflection) exhibited represents properties unique to effective Superelastic Niti wire
- Extreme elasticity and consistent force shown at 2.0mm deflection
•Peak load force of 230g at 2.0mm deflection is consistent with force levels at the 0.6mm deflection point during engagement
•Transitional rebound shows the wire is active and aggressive as engagement forces cease and recovery forces begin applying tooth moving force
- Consistent unload force as Martensitic state is reentered during recovery
•Tooth moving forces dissipate slightly then stabilize to ensure consistent unload to shape memory.
Average unload (tooth moving) force is 138.75g
- Shape memory and elasticity are expressed
•Full shape memory rebound occurs at 130g ensuring continuity of effective tooth moving forces through complete shape recovery
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