The lifetime of a well designed piezo actuator is not limited by wear and tear. Tests have shown that PI Ceramic PZTs Multilayer Piezo Stacks can perform 10 Billion and even 100 Billion cycles without loss of performance if operated under suitable conditions. NASA’s testing of these actuators validated their performance over 100 billion cycles, which aided their qualification for use as the foundation for the Chemistry & Mineralogy (CheMin) instrument.
Generally, as with capacitors, the lifetime of a piezo actuator is a function of the applied voltage. The average voltage should be kept as low as possible. This is why PI has specially designed actuators and electronics for semibipolar operation, an important advantage over conventional actuator/driver combinations.
PI Ceramic has conducted years of testing to come up with an equation to determine the lifetime of piezo actators. This is not an easy task because of the many parameters such as DC vs AC operation, temperature, humidity, voltage, acceleration, load, operating frequency, insulation materials, etc. which all have an (nonlinear) influence. PI PZTs are built for maximum lifetime under actual operating conditions. We do not manufacture our Piezo ceramics with the goal of maximum displacement at the expense of longterm reliability. The operating voltage range figures in the technical data tables are based on decades of experience with scientific and industrial OEM applications.
Statistics show that failures with piezo actuators often occur because mechanical installation guidelines are not observed and mechanical stress, shear forces and torque exceed the permissible limits. PI offers a variety of preloaded actuators, ball tips, flexible tips and custom designs to eliminate these critical forces.
While conventional piezo actuators with polymer insulation are usually strongly affected by humidity PI PICMA ceramic encapsulated actuators provide significantly better protection and several orders of magnitude longer lifetime under high humidity conditions. PI also offers waterproof and hermetically sealed actuators for applications in critical environments.
Application Example on how to reduce the operating voltage and increase lifetime: The P-842.60 LVPZT shall operate a switch with a stroke of 100 µm. The switch shall be open for 70% and closed for 30 % of it's operating time.
Optimum solution: The switch should be designed in a way that the open position is achieved with the lowest possible operating voltage. To reach a displacement of 100 µm, a voltage amplitude of approximately 110 V is required (nominal displacement @ 100 V is approximately 90 µm). Since the P-842.60 can be operated with -20 V, the closed position should be assigned to 90 V, and the open position to -20 V. When the switch is not operating, the drive voltage should be dropped to 0 V.