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Elfab Improves Lead Times with Schmidt Presses
30 June 2009
Elfab, Europe's leading manufacturer of rupture discs, is using a range of hydro-pneumatic and servo presses from SCHMIDT Technology to ensure that it provides the best lead times in the industry. Just as importantly, the latest SCHMIDT presses are helping Elfab to increase levels of accuracy and repeatability in the manufacture of precision engineered rupture discs for critical applications, where material thicknesses can be less than 50 microns and production tolerances just 3%.
Rupture discs are used throughout industry to provide critical points of burst control in a wide variety of pressurised and vacuum applications. These can range from in-flight oxygen systems for military aircraft, to cooling units in medical scanners, dust explosion protection devices in silos and bucket elevators, and gas insulation equipment for switchgear and circuit breakers in the power industry.
Elfab designs, manufactures and tests its wide range of rupture discs at its headquarters in Newcastle where the company's Senior Process Engineer, Graeme Melrose, points out that, "Our products are generally used in crucial process and safety applications, providing mechanisms that are engineered to fail in a precise and controlled manner. We manufacture forward and reverse acting rupture discs, in stainless steel and specialised high performance alloys, and in diameters from just 5mm to 900mm. These are designed to be used in, for example, tanks, pipes and pressure vessels, and provide extremely accurate control of burst pressures, typically up to 90% or 95% of rated burst pressure."
Each of Elfab's dome-shaped forward and reverse acting rupture discs incorporate a scoring line. This runs almost the entire way around the base of each disc dome, with a small portion left unscored to act as a hinge. The scoring line provides the critical point of engineered weakness that enables each disc to rupture at an exact and predictable pressure, and therefore has to be produced to extremely accurate tolerances.
Graeme Melrose explains, "The SCHMIDT press systems are used to form the scoring lines in each rupture disc using specially developed tooling, with side bars to hold the disc in place and a circular blade to form the scoring line. Although the tooling is relatively simple in construction its successful use depends both on the quality with which it is engineered and the level of control that we can exercise during the scoring process, to ensure that we form to the exact depth required to give the predicted burst pressure."
Elfab has used SCHMIDT press technology for some years, originally installing hydro-pneumatic machines and more recently ordering the latest servo presses with advanced computer control. "These are going to help us reduce our setup times and, just as importantly, enable us to improve levels of precision, repeatability and traceability still further; this will be especially important as we move into market sectors that require extremely high precision discs with wall thickness of less that 50 microns, and where we need to control the depth of scoring to a tolerance that is within plus or minus 3%".
The performance and quality of the presses is, however, only one of the reasons that Elfab chose to work with SCHMIDT Technology in the UK. "In addition", says Graeme Melrose, "SCHMIDT have provided an exceptional level of customer support and flexibility. For example, before we made a decision to purchase they allowed us to test our tooling at their support centre and have since provided continuous technical advice and engineering support to ensure that we have been able both to maximise the productivity of each production operation and to enhance the quality and reliability of our wide range of rupture discs."