Critical component failures often make the headlines, whether occurring at sea, underground, in mid-air or in production plants. Faulty pipes, valves, shafts, gears, couplings and other engineered components give rise to safety, environmental, productivity and financial issues, some catastrophic. These failures might result from design, manufacturing and assembly errors, inadequate quality assurance or unforeseen operating conditions, but sometimes they relate just to substandard materials and improper processing treatments.
Independent metallurgical specialist, Keighley Laboratories, points out that with growing volumes of steel, alloys and metal components being sourced in the Far East from comparatively unknown suppliers, and manufacturers in this country ultimately responsible for any component failures, there is now a pressing need to re-inspect, or overcheck, material certifications. In support of this view, the company draws attention to a recent US study, in which 133 out of 220 samples of imported steel rod were rated as failures by a certified test laboratory, an astonishing 60% failure rate.
“If you have specified imported material to a particular grade or heat treatment process, then overchecking is the best way to ensure you are getting what you paid for,” says Keighley Labs Heat Treatment Commercial Manager, Michael Emmott. “Often we find that the raw material is not as specified, even with the correct certification, creating potential problems down the line.”
“The cost of a simple chemical or mechanical overcheck or a full in-depth metallurgical analysis might be tens or hundreds of pounds, but if that item is safety critical or forms part of a product worth hundreds of thousands, then it’s a comparatively small price to pay,” he continues. “Besides, given the legal implications of a failure in the field, it’s either a question of verifying incoming material or possibly putting your own business at risk.”
Through its in-house Technical Services laboratory, Yorkshire-based Keighley Labs is able to provide independent chemical analysis, employing state-of-the-art spectroscopy or classical wet methods; microscopic sample examination, using metallography techniques; and mechanical testing for impact resistance, hardness, ductility, tensile strength and durability. In addition to overchecking certificated materials, these specialist techniques are also used in the allied fields of reverse engineering and failure investigation.
Reverse engineering refers to the process of duplicating an engineered component or assembly without recourse to drawings, CAD files, specifications or documentation, determining exactly how it was originally made and treated and from what material. Keighley Labs employs laboratory and CAD/CAM resources to model parts to a high degree of accuracy, then if necessary it will project manage the casting, machining and heat treatment of single or multiple components.
“Customers often ask us to re-engineer specific low volume, high value components and we apply reverse engineering techniques to such projects, usually introducing design and material upgrades to improve it to better than original spec, as part of the process,” says customer support manager, Len Stott. “Reverse engineering can also be invaluable for remanufacturing a vital replacement part, where the original manufacturer no longer exists or drawings have been lost.
“It is also useful for reclassifying mixed stock, where materials have been mishandled in storage and certification is missing,” he continues. “On mixed batches like this, we can test the hardness profiles, looking at depth and quality of case and the microhardness, then the surface hardness, to determine which material is actually fit for purpose and which has been wrongly classified.”
The Keighley Labs service also covers problem and failure investigation, employing forensic analysis techniques to determine why specific components have failed in the field, so as to prevent similar problems in the future. Its senior metallurgists, who have extensive experience across a wide range of materials, treatments and product types in many different industries, can also suggest from what material the component should be made and how it should be processed. It’s just another useful weapon in the fight against critical component failure.l