CLEANLINESS ANALYSIS - OVERVIEW
Initially, residual particles are extracted from the component surface by rinsing, spraying or ultrasound, and transferred to a liquid medium (fluid). The solid particles are prepared onto a membrane by vacuum filtration, enabling further analysis,
Selective evaporation separates the liquid flushing medium from oils, lubricants and other processing additives, which are subsequently weighed separately. The residue weight characterizes the degree by which component surfaces are contaminated with oil and fats.
The easiest way to quantitatively evaluate contamination by residual particles is to weigh the membrane before and after preparation. The difference between the two measurement results is the particle mass. For simple cleanliness requirements, this value is often sufficient.
Particle number and size are determined by analyzing the membrane with a scanner or light microscope. Due to their high working speed, scanners are not only suitable for standard analysis according to VDA-19.1 & ISO-16232, but also for process control of component cleanliness.
Technical sublime is the analysis by means of automated scanning electron microscopy and elemental analysis (SEM-EDX). In addition to number and size, this method also provides an individual typification of materials, hence allowing the particles' origin to be precisely constrained.
In the realm of cleanliness analysis, the current trend is shifting towards spatial measurements of particles. Thickness and volume of individual particles are important parameters, and can be constrained from X-Ray microtomography.