Testing Procedures for Qualifying Piezo Elements

Standardized Procedures Provide Certainty

Comprehensive quality management controls all production process at PI Ceramic, from the quality of the raw materials to the finished product. This ensures that only released parts that meet the quality specifications are passed on to further processing and delivery.

Electrical Testing

  • Small-signal measurements
    The data for the piezoelectric and dielectric properties such as frequencies, impedances, coupling factors, capacitances, and loss factors is determined in small-signal measurements.
  • Large-signal measurements
    DC measurements with voltages of up to 1200 V are carried out on actuators to determine the strain, hysteresis, and dielectric strength in an automated routine test.

Geometric and Visual Testing Processes

For complex measurements, image processing measurement devices and white light interferometers for topographical examinations are available.

Visual Limit Values

Ceramic components must conform to certain visual specifications. PI Ceramic has set its own criteria for the quality assessment of the surface finishes, which follow the former MIL-STD-1376 standard. A large variety of applications are taken into account, for special requirements there are graduated sorting categories. A general rule is that visual peculiarities must not adversely affect the functioning of the component.

The surface finish criteria relate to:

  • The surface finish of the electrode
  • Pores inside the ceramic
  • Chipping of edges, scratches, etc.

Measurement of Material Data

The data are determined using test pieces with the geometric dimensions laid down in the EN 50324-2 standard and are typical values. Conformance to these typical parameters is documented by continual testing of the individual material batches before they are released. The characteristics of the individual product can deviate from this and are determined as a function of the geometry, variations in the manufacturing processes, and measurement or control conditions.

>> Material Data: Specific Parameters of the Standard Materials

Quality Level

All tests are carried out in accordance with the DIN ISO 2859 standardized sampling method. For the electrical assessment, the AQL 1.0 level of testing is applied. A special product specification can be agreed for custom-engineered products. This includes the relevant release records, plots of the measured values or individual measured values of certain test samples and also the testing of each individual piece.

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