Improved microscopes are ensuring cleaner, uncontaminated parts for vehicle manufacturers, improving their durability and efficiency
As the need for a more efficient automobile gains pace, pressure is mounting on various elements of the auto industry to ensure clean, uncontaminated auto parts. Auto parts that find application in critical safety areas like brake systems, fuel injector nozzles, power steering pumps and fluid hoses could make a world of difference depending on how clean, or uncontaminated they are. Especially when it concerns coating adhesion for final product finishing.
A challenge that has continued to baffle even those suppliers that strictly adhere to the best practices in the industry. An important part of the challenge to ensure perfect coating adhesion, improved microscopes are helping develop a system to monitor adequate automotive part cleanliness.
Many methodologies in the process have been developed. One is bulk or gravimetric measurements; the others include particle counters and optical microscopes. Either methodology is claimed to provide only one parameter of diagnostic information, such as bulk particle weight, or particle size. They give clues as to what’s occurring in the manufacturing process. However, a single parameter is inconclusive, leaving companies with limited data to investigate the source of contamination.
As the challenge to keep costs down is forcing more and more automakers as well as suppliers to trim fat, devise lean process structures, the need for uncontaminated parts is assuming greater importance. This is bringing about a need to achieve a complete diagnosis with one test.
To achieve a complete diagnosis by performing a single test without leaving the production site. Without the need to go to an off-site lab. New analysers with electron microscopes could provide a solution, it seems. They help with rapid, automatic identification and detection for quality control. They are also providing clues to the source of the contamination.
Given the way the industry operates, particles found in automotive mechanisms can be a result of numerous sources. They can be intrinsic or extrinsic. Intrinsic particles can originate in several ways. From fragments of the mechanism material left by the manufacturing process, decomposition or erosion of friable components or structures (such as residual machining burrs) or wear particles produced by friction within the operating mechanism.
Extrinsic particles might include manufacturing residue from fabrication tools or processes, lubricant contaminants, or materials ingested from the environment. Monitoring cleanliness in automotive part manufacturing is valuable in view of it reducing field failure rates that occur in the first 15,000 kilometres.
While automotive manufacturers are known to have reduced their field failure rates up to 75 per cent in one year as a result of monitoring and making appropriate changes, cleanliness also becomes critical for surface finishing of auto parts. It is imperative that they are free of foreign debris in order to allow the coating chemistries to adhere to the substrate; any chemical interference that does not allow the coating to reach its maximum potential. This can cause cracking, or peeling. Worse still, it can lead to failure as the coating is unable to protect the part.
Quality conscious manufacturers have been finding it increasingly necessary to ensure the critical cleanliness of their parts and processes as potential contamination sources increase and tolerances in engines decrease. Since monitoring cleanliness has proven to be so beneficial for controlling costs, the International Organization of Standards developed the standard 16232-07.
Adhering to standardized regulations creates mutual understanding between manufacturers and customers. European and American manufacturers led the automotive industry in adherence to the ISO mandate, resulting in a surge of innovative techniques for determining the cleanliness of manufactured automotive components.
Electron microscope has greater resolving power than a light microscope and can reveal the structure of smaller objects because electrons have wavelengths about 100,000 times shorter than visible light photons. They can achieve better than 50 pm resolution and magnifications of up to about 10,000,000x whereas ordinary, non-confocal light microscopes are limited by diffraction to about 200 nm resolution and useful magnifications below 2000x. The electron microscope uses electrostatic and electromagnetic lenses to control the electron beam and focus it to form an image. These electron optical lenses are analogous to the glass lenses of a light optical microscope. Electron microscopes are used to investigate the ultrastructure of a wide range of biological and inorganic specimens including micro organisms, cells, large molecules, biopsy samples, metals, and crystals. Industrially, the electron microscope is often used for quality control and failure analysis.
Modern electron microscopes produce electron micrographs, using specialized digital cameras or frame grabbers to capture the image. CleanCHK analyser from FEI for example, monitors automotive part cleanliness right on the production floor. First fully automated particulate contamination monitor specifically designed for automotive applications, it monitors automotive part cleanliness by providing particulate data within minutes, right on the production floor.
CleanCHK allows an administrator to set up the calibration and testing sequences and have this information stored in the instrument so any operator can simply load the samples and hit ‘go’.
Once activated, the instrument takes over and the user can literally walk away and come back when the samples are completed. This feature eliminates the need for users to manually run calibration and set up the instrument, freeing them up to resume their normal duties while the samples are being tested.
CleanCHK’s reporting module was designed to allow users to comply with industry standards such as ISO 16232 and VDA19, or incorporate their own standards. It automatically classifies each sample according to the component cleanliness code in compliance with the standard, and can generate reports using only the larger particles or by trending data through histograms. Allowing for rapid search of large areas in a sample, targeting problem particles while disregarding ’empty’ spaces or benign materials in the sample, CleanCHK is durable enough to be used right on the production floor. The analyser has a small footprint, which allows it to be installed close to the production line, allowing immediate access for monitoring. Engineers and QA managers can immediately identify the source of potential contamination and quickly fix the issue, which ultimately results in reduced failure rates, recalls and costs.
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