A Piezo Actuator boosts great drive properties including:
- Travel range is available to several hundred micrometers
- Unlimited resolution in principle as the motion is based on solid-state effects
- High force generation and dynamics, with very high stiffness
- Several hundred kilohertz of high resonant frequency gives rapid response time in the microsecond range
Being insensitive to push force a piezo actuator needs to be protected against pulling and shearing stress. To achieve this a housing can insulate electrical contacting and mechanically decouple literal forces. Furthermore, a preloaded spring is applied between the piezo ceramic and housing to prevent pull forces caused during dynamic operation.
Piezo Actuators with Flexure Guides
To achieve straight motion the piezo needs to be embedded in a guide. Additionally the mechanical guide will ideally also integrate preloading and force decoupling while not effecting the system stiffness.
Flexure guides motion is based on the elastic deformation of a solid, which acids any static, rolling or sliding friction. Furthermore, the hysteresis-free motion makes it suitable for positioning tasks up to several millimeters.
Flexure Guide Characteristics
The advantage of a Flexure Guide is high stiffness, lead capacity and wear resistance. Manufacturing is done based on nonmagnetic materials, and as lubricants or consumables is not required it is both maintenance free and will operate without problem in vacuum.
Constant Velocity and Smooth Driving
When integrating a lever mechanism the travel range can be multiplied. The travel range is extended up to 2 mm as the actuator is mechanically integrated in a flexure joint. A flexure guides design requires much more complex geometries as simple lever structures lose a considerable amount of guiding accuracy and stiffness.
Exteramly high path accuracy is achievable with flexure motion. Height and transversal offset is compensated by a special multi-link flexure guide (developed by Physik Instrumente). This guiding system, integrated in most nnaopositioning systems, allows straightness and flatness in the micro radian or subnonomter range.
Lever Amplification enabling Millimeter Travel Ranges
Piezo stack actuators has a displacement of typical from a few ten up to a few hundred micrometers. The flexure guide has the capability to act like a mechanical lever and if necessary amplifies the displacement and guides the piezo actuator into a different direction.
Taking into consideration that the lever always leads through a pivot point but still needs to prevent lateral migration and needs to be guided in a straight line, this makes for an extremely demanding design.
Increased travel range effects stiffness but the flexure guide can be designed so that additional integration will not require additional guide. To achieve this flexure joints are employed for levering and guiding.
Actuators with Bulit-In Lever Guide for OEM applications
With high precision frictionless flexure guides, such as the PiezoMove® actuators, it is possible to combine travel ranges up to 1 mm and precision up to 10 nanometers with the inclusion of optional sensor.
The number and size of actuators used will determine stiffness and force generation. Flexure guides will still maintain a very high stiffness and extremely low lateral displacement making them easy to handle in comparison to simple piezo actuators. Furthermore, considering above mentioned benefits and the small dimension PiezoMove® lever actuators have it is a great alternative for OEM applications.
Integration levels of Piezo Actuators
Stack Actuator to 6-Axis Positioning System
There are a numerous integration levels offered for piezo actuators. Depending if you need a simple drive component with an integrated nanopositning sensors in single-axis stage or a multi-axis positing stages controlled via a digital controller for highly complex situations there is an piezo actuator option for you.
|Stack Actuators||Lever-amplified Actuators||Positioning Systems|
|Travel range||up to approx. µm||to 1 mm||to 1 mm|
|Axes||one||one||up to 3 linear axes and 3 tip/tilt axes|
|Sensor Technology||optional SGS||optional SGS||SGS or direct measuring|
|Linearity||up to 99.8 %||up to 99.8 %||more than 99.9 %|
|Guiding||none||Flexure joints for tilts <10°||Flexure joints for tilts <2°|
|Space requirement||low||low||depending on configuration|