Contamination testing of mechanical parts is crucial to ensure the quality and reliability of components in a wide range of industries, from automotive to aeronautics to medical. These tests are designed to determine the amount and type of contaminants present on the surface of workpieces.

In particular, the extraction phase of the contaminant and the subsequent analyses, gravimetric and granulometric, play a fundamental role in obtaining a complete assessment of the degree of contamination.

To carry out the extraction phase we use different methods such as: ultrasound, pressure washing, internal flushing and stirring.

Gravimetry:

Gravimetry focuses on the measurement of the total weight of contaminants present in the sample. The contaminant is removed from the component with a specific solvent, which removes the dirt particles. The solvent is then filtered by trapping the particles on the filter membrane.

The difference between gross weight at the end of the test and the initial tare will give, thanks to the use of a high resolution balance, in analytical terms the required result of the total weight of contaminants.

Grain size:

Particle size, on the other hand, is concerned with analysing the size and total quantity of contaminant particles. Several techniques are used, including:

• Optical microscopy: thanks to the use of state-of-the-art software, the analytical membrane is scanned automatically. Digital sample images are analyzed by specific software to count, identify and classify contaminant particles according to their size. We can work according to the ISO 16232 classes or set parameters based on your requirements.
• Scanning electron microscopy (SEM): this technique allows high resolution images of individual particles, allowing the size to be measured with extreme precision and their morphology to be analysed.
• SEM+EDS scanning microscopy: The use of the x-ray probe provides further information on the chemical nature of particles.

The results obtained from gravimetric and particle size analysis are compared with specific reference standards established according to the type of component, material and intended use. This allows you to determine whether the level of contamination is acceptable or whether the component requires further cleaning.

Ultimately, contamination testing provides crucial information to ensure the quality and reliability of mechanical parts, thus contributing to the safety and efficiency of industrial systems.