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Selection Guide for CEDRAT's PPA Actuators
Standard bare ceramic actuators are sensitive to tensile forces. In order to enhance the operational characteristics, piezoelectric actuators are typically operated under a pre-stress force. In some applications, the pre-stress can be applied directly by the mechanism using the piezo-actuator. In other cases, the application demands for a housed actuator already pre-stressed. CEDRAT offers a wide range of pre-stressed actuators.
Direct Piezo Actuators (DPAs) are the most common type of pre-stressed Actuators. They consist of a stack of pre-stressed active material. Conventional DPAs use a serial pe-stress. The level of pre-stress determines the pulling force capability.
A more robust technique (widely used at CEDRAT in power ultrasonic transducers) consists of a parallel pre-stressed with a bolt-tightened steel rod. However, this approach requires mulilayer actuators having ring shape, which are less common and more expensive.
A third alternative consists in pre-stressing the actuator through an external elastic frame, leading to a Parallel Pre-Stressed Actuator, PPA.
DPA and PPAs are solid-state linear Actuators. They use only the expansion of the active material in the "33-mode" thus producing a useful displacement. This displacement is proportional to the voltage on a 170V range. Typically, the Actuator deformation is about 0.1% (1um/mm), so their displacements are limited to about 100um. In counterpart, the forces are naturally large, easily higher than 1kN. DPAs are using a conventional series pre-stress. So they are limited to quasi-static applications such as micro positioning.
| PPA Model Series |
PPA M
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PPA L
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PPA XL
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| Blocking Force [N] |
800
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18
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40-100
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| No-load stroke [um] |
10-40
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25-80
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60-120
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| Strain Gauge Opt. |
Yes
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* (except 50XS)
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Yes
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| Non-Magnetic Opt. |
Yes
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Yes
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Yes
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| Mech Interface Opt |
TH
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FI-H-TH-SI
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FI-H-TH-SI
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| Electrical Interface Option |
Two wires AWG30
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Two wires AWG30
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Two wires AWG30
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| Notes |
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Larger actuator
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Examples of some CEDRAT PPA Actuators Series
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PPA M SERIES
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PPA L SERIES
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PPA XL SERIES
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Click the above picture for datasheets on the PPAs.
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More information
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Related links
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