Technology update
Batch efficiency
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AGIE electro discharge machines integrate single flow manufacturing at Lucas Aerospace.
At Lucas Aerospace, the AGIE Classic erodes difficult profiles on stainless steel valve sleeves for fuel metering equipment.
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Achieving economically effective batch production can often be a problem for the aerospace industry. To help it reach that aim, component supplier Lucas Aerospace has integrated an electro discharge machining (EDM) system by the Swiss-based company, AGIE. Lucas is using a single-flow method, with the AGIE machines helping the company achieve smaller batch production, reducing stock levels and improving throughput times. Lucas Aerospace established a special team to spend six months planning five cells for a one-piece material flow mainly for valve production at one of the company's facilities in Birmingham. The valves are used for many applications, including the Rolls-Royce Trent engine as well as engines for various aircraft such as the new multi-national Eurofighter Typhoon and several Airbus variants. The project team identified part groups and specific machining routes for individual components. The first U-shaped manufacturing cell is based on the Toyota production system and works on 90 different components, with an operator moving each part around the machines, completing one stage before progressing to the next.
An AGIE Classic wirecut and Innovation diesink have been installed for the machining of difficult profiles on stainless-steel valve sleeves for fuel metering and pump units. "The EDMs form a branch line down the middle of two cells, together with an optical measuring machine and lapping and cleaning stations," explains AGIE. "Components are moved on the branch line once they have passed through the necessary machining stages in one of the two main cells, which comprise CNC (computer numerically controlled) turning machines, a CNC milling machine, a drilling station, deburring stations, and honing."
Profiles eroded by the AGIE machines require a tolerance of ±10 µm. Because of their small dimensions and position on the curved side surface of the valves, this would be difficult to machine using a method other than an EDM, said the company. Lucas Aerospace calculated a typical total sequence time, excluding EDM, to be 15 minutes for the main cells. This was determined by dividing the 4000 machining hours available each year by the 16,000 parts each cell has to produce. This means that every 15 minutes, a valve needs to be completed on the main cells ready to pass to the AGIE machines for erosion of the profiles. To avoid a bottleneck at the erosion stage, the company has divorced the EDM process by creating a branch line that relies on the Classic and Innovation to provide a low cycle time of about one hour.
Repeatability was particularly important as single flow emphasized the need for consistent, guaranteed quality. Single flow provided various benefits. AGIE explained that in the past, each machine required a dedicated operator, but now an operator has multiple tasks, overseeing one machining operation before moving the workpiece to the next stage. As parts are not stockpiled at any one machine, considerable time, and therefore cost savings, are made, and lead times have been markedly improved, in some cases from eight weeks to just one, according to the company. All machines within the cell are programmed centrally, significantly reducing programming time. Stock levels are also kept to a minimum as a part is fully completed on the cell, boxed, and ready for the customer.
Stuart Birch
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