TiNi Aerospace
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FAQ  >  Pinpullers
TiNi Aerospace, Inc.

Shape Memory Alloys



Is the SMA used to retract the Pinpuller output Pin? No, the Pin is retracted under the force of a "Compression Spring" made of conventional materials. Rather, the SMA (or TiNi) is used to release the latch which initiates movement.
Can you raise the resistance of your Pinpullers (or ERMs) so they can be operated from higher bus voltages (such as 20-70 Vdc) without exceeding your current limit? Yes, we routinely do this for many applications by simply incorporating an inline resistor which is capable of dissipating the power required. Generally, this is not a problem because the function times are sub-second and therefore result in very little energy (Joules) dissipated.
How does TiNi determine the rated force of the Pinpullers? As an example, TiNi's P10 Pinpuller provides a minimum force available at the start of the travel which is 10 lbf. The retraction force at the end of travel however may be significantly lower at approximately 5 lbf. This is consistent with the requirements of most applications where the maximum required force is at the start of travel when overcoming static friction.
Are the Pinpullers vented? Yes, unless otherwise required, all TiNi products are vented for space use.
Does it matter where on the Pin the load is applied? As with all such applications, it is best to apply the load as close to the supported section (Pinpuller Flange) as possible. However, the quoted specification is based on worst case situations where the load is applied at the end of the Pin forming the greatest moment.
How does TiNi make the Pinpullers (and ERMs) operate so fast? The TiNi element is "Joule Heated" (i.e. the current is passed directly through it such that it can be heated very quickly).
What establishes the upper maximum temperature of the Pinpuller, ERM, or Frangibolt? This is limited by the self-actuation temperature of the device (i.e. the maximum operating temperature must not exceed the temperature at which point the device risks functioning without the application of power). All TiNi standard products maintain a conservative margin of 20C from this temperature.
Are the Pinpullers manufactured with any type of lubricant? Yes, a small amount of wet lubricant in the form of Castrol Braycote 601 EF is used during assembly. This can be omitted entirely or changed to other lubricants if required. Also, sliding parts are generally plated with MoS2 or Teflon impregnation as offered by companies such as Tiodize (El Segundo, CA).
My application requires small modification to force, stroke, and or mechanical interface. Is this a problem or costly to implement? No, we do this routinely and unless the working mechanism is changed and a "delta-qualification" effort becomes necessary, modifications such as these are simple, quick, and not expensive.
Has TiNi ever performed a true life test on the Pinpullers (Frangibolts or ERMs) to determine the actual failure point? No, all of our products are deemed capable of thousands if not many millions of cycles. The rated Life of approximately 100 cycles (for all actuators) is therefore based on applications requirements and not what the device can do.

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