Nitriding furnaces know their place

Ancillary process equipment, including a solvent degreaser and pre- and post-treatment washers for removing any surface contaminants, are also being integrated into the streamlined workflow arrangement. Housed in a 5,000 sq ft purpose-built department, with a thermal insulation envelope designed to ensure optimum energy efficiency, the £1 million plus development adds the latest low temperature, low distortion thermochemical processes to the Keighley Labs' heat treatment portfolio. It will meet more sophisticated surface engineering requirements for its existing customer base in the railway, mining, oil & gas and general engineering sectors, whilst opening up new applications in the aviation, nuclear power and renewable energy markets. In due course, the West Yorkshire company is hoping to gain NADCAP accreditation for this new department, to match the Materials Testing Laboratory accredited status for its Technical Services division. "We will have the new vertical pit, gaseous nitriding facility up and running in the spring of 2014, at which point we shall have amongst the best, most up-to-date low temperature, low distortion resource in the independent heat treatment sector, with the very latest process control software," said Michael Emmott, divisional commercial director for Keighley Laboratories Heat Treatment division. "We've had a lot of interest from customers wanting to send jobs for processing already, but we wanted to conduct sufficient trial runs in order to obtain repetitive results, which will ensure meeting the quality and precision standards that the industry expects of Keighley Laboratories." Gaseous nitriding and nitrocarburising are heat treatment processes that enhance the surface properties of finished and near-finished metallic components. The gaseous nitriding process promotes wear resistance, together with corrosion resistance in the case of nitrocarburising, and these low temperature techniques ensure minimal distortion of the workpieces. In nitriding, the surface of the ferrous metal is enriched with nitrogen to improve wear resistance, fatigue strength and other characteristics; whereas with nitrocarburising small amounts of carbon are also introduced into the process, resulting in a more flexible compound surface layer, with good lubricant retention properties, as distinct from the classical white layer of gaseous nitriding. The gaseous nitro carburising sealed quench furnace is an IPSEN TQ7 gas-fired unit, which consists of a process-tight chamber with an integrated double-walled quench chamber, enabling the complex heat treatment cycle to take place in a protective environment. The new heat treatment department will offer gaseous nitriding and both ferritic and austenitic nitro carburising, the latter enhancing indentation resistance, and both methods can be used for upgrading components made from relatively inexpensive, lower alloy materials. The load bearing characteristics and other beneficial properties of these treatments make them typically ideal for rail industry components, bearing shafts, cams and crankshafts. For their new processes, Keighley Labs envisages treating a wide variety of components, helping to substantially improve wear resistance, fatigue life and anti-corrosion properties. Both low distortion techniques mean that finishing operations such as post-grinding and machining can be eliminated or kept to a minimum.