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Francesco Piscani

Metrology

An Introduction to Technical Cleanliness Inspection

Component cleanliness is an integral part of industrial manufacturing processes

Published: Wednesday, October 11, 2017 - 11:03

The cleanliness of components and parts is at the center of most industrial manufacturing processes, as these components must be free of contaminants to ensure a high-quality finished product. Technical cleanliness inspection involves quality control, process management, and manufacturing departments taking samples from the production line and utilizing particle extraction through filter membranes to quantify contaminants that may affect the performance, lifetime, and reliability of final products.

What are the basics of technical cleanliness?
The growing complexity of today’s technical products, especially within the aerospace, automotive, heavy equipment, and electrical engineering industries, has resulted in an increasingly high demand for product reliability and quality assurance. The durability and life cycle of a finished product depends on a number of characteristics, all of which contribute to its measurable technical cleanliness:
• Quality and characteristics of the product material
• Fitting tolerances
• Overall cleanliness of a surface or particle load

How does technical cleanliness affect a product’s reliability?
Product contamination, which usually occurs during manufacturing but can also be the result of storage, cleaning, or handling, has a direct influence on a finished product’s reliability and its lifespan. The dangers of unclean surfaces or production liquids can range from function loss to product failure to complete breakdown.

For instance, the coolant flowing through a radiator’s tube helps cool an automobile’s engine. If contaminants are left inside the tube when a radiator is manufactured, it may decrease cooling efficiency and even damage the engine. The inside of the tube must be thoroughly cleaned throughout the manufacturing process, and the cleanliness level rigorously inspected.

Residues on the surface of technical devices used in manufacturing and assembly processes can cause unreliable or poor device performance, downtime in production, or the waste of materials and energy. Large residue particles (sometimes called “killer particles”) may cause complete function loss. With the ever-decreasing size of system components, smaller residue particles can also cause catastrophic failures and lead to the breakdown of an entire end product.

In what application areas is technical cleanliness most important?
The cleanliness of components and parts is critical to the manufacturing process. Here are a few basic illustrations of the importance of technical cleanliness in relation to specific industries:
Heavy machinery: Because the very large parts that make up a lot of heavy machinery can be difficult to reach and directly inspect, the inspection of these products can become costly. Therefore it is more cost- and time-effective to inspect used oil for particles rather than inspect the machine itself. The status of the oil is an extremely accurate indication of the condition of a machine.
Electrical engineering: If there are particles on an interconnect during the production process, that is an indication that they have not been properly built. The detection of these particles, and subsequent eradication, is a good way to avoid short circuits on printed circuit boards.
Automotive: Within the automotive industry, there are many intricate systems and parts that need to be free from contaminants. These may include ABS systems, fuel injectors, brake calipers, and hydraulic fluid systems. For instance, a diesel injector is a vital, ultra-precision part used in diesel engines. The injector has a small nozzle orifice (50 to 250 μm) that injects diesel fuel into the engine’s combustion chamber at high pressure. If the nozzle is clogged with contaminants, the engine’s efficiency may decrease, and the engine or injector may be damaged.

What is the technical cleanliness inspection process?
Proper technical cleanliness inspection is based on a clear, established process that utilizes particle extraction on membrane filters to quantify contaminants that directly affect the performance, lifetime, and reliability of finished products. Particles are taken from sample components via flood, squirt, rinse, or ultrasonic bath, and then collected on a membrane filter. Once the filter is dried, it is then inspected using a multi-step inspection process to identify and analyze the contaminants in question. The contaminants are analyzed in accordance with international standards such as ISO 16232 (VDA 19.1) and ISO 4407.

In the case of the diesel injector inspection process, counting the number of contaminant particles is an important method for evaluating the cleanliness of injectors. The contaminant particles are first removed using a liquid shower or an ultrasonic bath. The washing rinse is then filtered through a membrane to collect the extracted particles, and the filter membrane is dried for the further analysis. Once the sample is fully prepared, the particles trapped on the filter surface are evaluated using a microscope. Once the size and number of particles are quantified, the data must be analyzed and evaluated according to industry standards to determine the injector’s technical cleanliness.

What kind of system is required to conduct technical cleanliness inspection?
Technical cleanliness inspection presents a number of unique challenges, including the need to regularly check results during inspection, view multiple particles simultaneously, revise results based on various standards, and quickly circulate results. Designed specifically to address these challenges, the Olympus CIX100 technical cleanliness inspection system is a dedicated, turnkey solution for manufacturers that need to maintain high-quality standards regarding the cleanliness of manufactured components.

The CIX100 makes it easy to quickly acquire, process, and document technical cleanliness inspection data while maintaining the highest quality standards. Dedicated, easy-to-use software workflows minimize user action and guarantee reliable data while enabling the detection of reflective and nonreflective particles and contaminants, from 2.5 µm up to 42 mm in a single scan. The system also counts and sorts particles into size classes defined in the inspection configuration.

Operators can review, revise, and recalculate inspection data at any point in the process on a single screen, including live and overview images, with simple-to-use “Delete Particle,” “Split Particle,” and “Merge Particle” software tools. Full-sample views display the complete particle even when the image has been stitched together. Analytical reports that comply with the standard used during analysis can be created as Word documents or PDFs with a single mouse click. There’s also an option for digital image zooming.

From extraction, filtration, and weighing, through inspection, review, and reporting, the CIX100 simplifies and optimizes every step of the technical cleanliness inspection process.

The system is intuitively designed to guide users through each step of the process—from extraction, filtration, and weighing through inspection, review, and reporting—so that even novice inspectors can acquire important cleanliness data quickly and easily.

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About The Author

Francesco Piscani’s picture

Francesco Piscani

Francesco Piscani is an applications specialist for Olympus Corporation of the Americas, Scientific Solutions GroupPart of the Olympus team since 2015, Piscani provides customers and sales staff throughout the Eastern United States, Canada, and Latin America with product and applications support for industrial microscopy products including metallurgical, measuring, and digital microscopes; semiconductor equipment; and image analysis software.