Test & measurement
Fasteners play a crucial role in an assembly - yet quality standards are often overlooked. If a fastener is not made to specification, manufacturers may be unable to assemble their products, facing long lead times before the right parts arrive. In a worst-case scenario, manufacturers risk sending poor-quality products out to the market, risking loosening or component failure. This would result in product recall, an expensive, extensive and embarrassing process, which can significantly damage a company’s reputation. Here TFC’s Brian Vince shares insight on common fastener problems, and how to avoid them
Hardness testing can also detect quality
issues. Quality specialists can assess tensile strength and perform flexure or compression tests to check the material has the desired properties. This will prevent a fastener from going into an application where it is too hard and will snap, or too soft and will bend. Dependent on the component at hand, other tests can be performed, such as load testing for springs, checking the hardness of rubber parts with a durometer, or testing the smoothness of bolt. If all testing is coming up fine, but a manufacturer experiences problems with quality during assembly, inspecting the part under a microscope means you can interrogate the problem at a very granular level to identify what is wrong.
MATERIAL To check that the fastener is made using the required material, quality professionals can use positive material identification (PMI) testing. This technology analyses the full chemical composition and grade of a metal or alloy, which means that the manufacturer can be confident that the material’s properties match specification. Material identification is particularly important in the oil and gas sector, where a material mix up could lead to catastrophic failure. For example, a
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stainless-steel retaining ring in a subsea drive shaft, instead of specified Inconel X-750 could mean drilling operations are forced to halt months before schedule. If all testing confirms that the part is to
specification, it may be a design issue that is causing quality problems. In this case, your supplier may be able to suggest an alternative option that will be more suitable for the application.
RE-ENGINEERING There is another benefit to having access to all this kit. As well as checking the quality of a fastener from a supplier, testing methods can be used to help re-engineer a component. For example, if you are not sure what material your fastener is made of, PMI testing could identify the material. Combining this with measurement techniques that provide the physical characteristics of the fastener could enable you to work backwards to identify an alternative part that would work in the same application. While the majority of fastener
manufacturers have the equipment to fully interrogate fastener quality, not all distributors possess the same advantage. If there is a non- compliance report, it pays to work with a distributor that tests in-house, rather than outsources, as external quality testing can take four to six weeks compared with next day.
COMMUNICATE AND COLLABORATE To make sure they have the best possible chance of fastener success, manufacturers should be rigorous with their suppliers — ask to see their certifications and establish what quality measures they have in place. A good starting point is ISO 9001, but there are other ISO and AS standards, as well as OEM approvals and lot traceability certification you can check for. Certain industries have more rigorous certifications, such as Aerospace AS9100:2016/9120:2016 standards (AS 9100D and AS 9120). Good communication and full traceability
between distributor and supplier is crucial. Consolidating your suppliers into one vendor managed inventory partner, or reducing the number of vendors, will make managing quality more straightforward.
TFC does all quality testing in-house to
make sure that customers are receiving the correct parts, to specification. It proactively checks parts, so its customers do not have to. If you need a supply of fasteners checked in a
way that has not been mentioned, let TFC know. The company is always happy to add equipment to its test lab to meet customer needs.
TFC
www.tfc.eu.com
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