Piezo Actuator-Linear Motion
CoreMorrow piezo ceramic/stack
Q: I want to apply a layer of paint on the piezoelectric ceramic. Will it reduce its displacement?
A: Any additional material parallel to the piezoelectric ceramic will increase the load on the piezoelectric ceramic, thereby reducing its performance. However, in most cases, the stiffness of the outer garment will be lower than the stiffness of piezoelectric ceramics, so the effect is small (<5%).
Q: Can I use oil to cool piezoelectric ceramics?
A: Yes. For some applications, the heat generated by the piezoelectric ceramic itself (self-heating) is significant and can be cooled by air or oil flow. The cooling oil must be clean dielectric oil (insulating oil), because any impurities may cause electrochemical reactions, which eventually lead to damage and failure of the piezoelectric ceramic. Also note that for piezoelectric ceramic with large cross-section, the thermal gradient between its surface and inside may be large, so maintaining an acceptable surface temperature may not be sufficient. Optional CoreMorrow air-cooled piezoelectric actuator, equipped with cooling vents.
CoreMorrow add cooling piezo actuator
Q: Can I apply torque to piezoelectric ceramics?
A: It is not recommended to apply torque to piezoelectric actuator. When applying a pre-tightening force to the piezoelectric actuator through the nut, it must be ensured that the pre-tightening torque is not transmitted to the piezoelectric actuator. A shear force greater than 1 MPa may cause fracture of the piezoelectric actuator interlayer. The torque piezoelectric actuator can be used CoreMorrow to solve the torque problem.
CoreMorrow withstand torque piezo actuator
Q: How much preload can I apply to piezoelectric ceramics?
A: We recommend that piezoelectric ceramics work under a preload of 0~80MPa. The design of the preload force must ensure that under any conditions, the preload force is within this range. The normal value is 10~20MPa.
Q: Can I apply negative voltage to the piezoelectric stack?
A: Yes. The displacement of the piezoelectric ceramic under quasi-static can be increased by applying a certain negative voltage. However, in order to avoid the risk of piezoelectric ceramics being depolarized, the electric field should be limited: at room temperature and no load, for N51 and N57 materials, the negative voltage must not exceed -0.7kV/mm, for N59 materials -0.25kV/ mm, N46 material is -1.5kV/mm. In the case of high temperature and high load, these recommended values must be reduced.
Piezo Actuator-Bending Motion
CoreMorrow piezo bender
Q: I can't measure the resonance frequency value in the parameter data of the piezo bender. What is the reason?
A: First resonance frequency will be higher, so the clamping force has an effect on the resonance frequency. Similarly, applying a load (such as a lens, etc.) to the top of the piezo bender will lower the first resonance frequency.
Q: How to deal with the internal electrodes of the multilayer piezoelectric ceramic exposed?
A:For multilayer piezoelectric ceramics, if the internal electrodes are exposed, the applied voltage Vmax needs to be reduced to avoid arcing. The exposed area must be coated. For safety, please replace with new piezoelectric ceramics.
Piezo Actuator-Shear Motion
CoreMorrow piezo shear
Q: There is no generated force mentioned in the piezoelectric shears. What is its generated force?
A: For piezoelectric ceramic shears, due to its high stiffness, it is very difficult to measure its generated force. This is the reason we did not mention in the parameter data. The force can be estimated by multiplying the free displacement and the stiffness. The stiffness value can be obtained by S55E, and the value of S55E is 4.3e-11m^2/N.
Q: Can piezoelectric ceramic shears be used at high frequencies?
A: Due to its high stiffness and high resonance frequency, piezoelectric ceramic shears can be used for fast operation (fast response). However, continuous high-frequency use may cause problems. This is because its nonlinearity means high loss (higher than d33 ceramic), so the piezoelectric ceramic itself will generate heat. Generally, working at 2kHz for a few minutes is not a problem. If higher frequencies or longer durations are required, the applied operating voltage must be reduced, otherwise the piezoelectric ceramic will slowly depolarize (loss of polarization).
Q: What is the recommended preload for piezoelectric ceramic shears?
A: d33 piezoelectric ceramic stack needs to be pre-tensioned during high-frequency use, because the inertial force will become significant, and tensile stress will be generated inside the piezoelectric ceramic. For shear-type piezoelectric ceramics, its inertial force is a shearing force, so the effect of axial preload is limited. But in some cases, in order to improve the rigidity (by compressing the glue layer / glue line) or to avoid bending (if the center of gravity is far from the fixed end), the axial preload is very beneficial.
Q: What is the maximum axial load that can be applied to the piezoceramic shears?
A: Piezoelectric ceramic shears are usually tested under pressure of 3.5MPa. Piezoelectric ceramics can withstand higher compressive forces (>50MPa), but in practical use, we recommend that the axial load of the piezoelectric ceramic shearing sheet should not exceed 5MPa. This is because small defects on the contact surface can also lead to stress concentration, thereby destroying the piezoelectric ceramic. If high pressure is required, we recommend using a higher flatness contact surface (including the contact surface of the piezoelectric shear plate surface and the structure).
Q: What is the maximum shear load that can be applied to the piezoelectric ceramic shear?
A: Piezo ceramic can withstand very high loads. In fact, the interface between the ceramic and the substrate determines the maximum shear load. If the motion is transmitted by friction, the maximum load will depend on the pressure at the contact surface and the coefficient of static friction. For example, 2MPa pressure × 0.2 friction coefficient = 0.4MPa, for a 5×5mm shear sheet, its maximum shear load is about 10N.
If epoxy bonding is used, the maximum shear load will depend on the strength of the epoxy used. Generally, epoxy resin can be safely used under a shear stress of 5MPa, and it can be used on a 5×5mm shear sheet. Its maximum shear load is about 125N.