Reliable measurement – Piezo sensors: perfect test results, from the widest measuring range down to the smallest sub-range

Piezo sensors are used to reliably measure pressure, acceleration, tension or force. They are based on the piezoelectric effect which is due to the ability of crystals to generate an electric charge in response to applied mechanical stress.

The applied force is always absolutely proportional to the electric charge (piezoelectricity). This effect thus enables process forces in industrial applications to be reliably measured.

Function of piezo sensors

Mechanical stress is converted into electric output signals already in the quartz. Contrary to other measurement principles such as strain gage technology, the quartz measuring element of the piezo sensor functions as a mechatronic component: The applied force is converted into an electric output signal by a change in charge resulting from the stress applied to the quartz.

Advantages of piezo technology

One advantage provided by piezo technology is that the elastic deformation of the quartz that occurs is very small, in the range of a few micrometers. This enables extremely stiff mechanical designs to be easily implemented. In addition, the sensitivity of piezo sensors is generally independent of the measuring range and consistently remains on a high level over a long period of time. Therefore, 5 kN can be measured with a 140-kN sensor as precisely as with a 5-kN sensor. The positive effect: sensors achieve extremely high overload capability without loss of accuracy. Piezo technology thus allows precise and reliable measurement in a wide measuring range down to smallest sub-ranges. Another inherent advantage of piezoelectric measurement technology is that it enables the slightest variations to be precisely and reliably measured even with high base loads. The base load can very easily be “zeroed”. The advantage: The output signal of the piezo sensor, i.e. the charge shift, is definitely cancelled.

In brief

Piezoelectric force measurement technology offers outstanding features for reliably monitoring assembly and test processes in production:

• Resolution and sensitivity are independent of the measuring range and allow for overload safe operation.

• The very compact design enables piezoelectric sensors to be used where space is a constraint.

• Extremely high stiffness and, at the same time, measurement with practically no displacement allow many measurements to be taken with high reliability

• Charge signals can be easily added up.

Files:

 Piezo for process control (71 kB)