[News] Rosler Helping to Reduce Production Costs and Increase the Quality of Aero Engine Blades

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If an aerospace engineer were to show even a small finished aero engine blade to a person outside the industry and ask them to estimate its production cost, it is unlikely they could do so, because it is difficult for an “outsider” to appreciate the skill and time required to produce it. Multi Axis machining centres are widely used in the industry and have played a significant part in the quality/ cost factor. Surface finishing however is still an expensive and time-consuming part of aero engine blade production, and it is in this area that Rösler have and are playing a major role in the design and supply of finishing equipment to the World's engine builders and repair centres. A well known UK based aero-engine manufacturer for instance have recently invested heavily in Rösler finishing machines for their new purpose built factory. Forged blades require de-Scaling between forging stages and this manufacturer chose the Rösler Multi-Nozzle Thru- Feed Blast Machine for this operation. The transport belt and nozzles of the SBI 1200. Blades are loaded by conveyor once a heat sensor has determined that they have cooled sufficiently They exit onto a motorised circular table to avoid damage, having been exposed to the aluminium oxide shot for seven minutes. There is a first and second stage forging process which produces the familiar shape of an aero engine blade. The surface at this stage will be clean from the work carried out in the SBI. The surface of the aerofoil and platforms now become important features of the component, The finishing of these surfaces was traditionally carried out by hand using abrasive belts and wheels. A highly skilled and expensive process that Rösler helped to supersede with the development of the vibratory finishing machine and special ceramic abrasive medias that were developed and produced by them. The modern method of blade finishing is the Rösler FKS35 1A2 high energy centrifugal force finishing machine. The FKS is able to cut down the surface of a component up to twenty times faster than a conventional vibrator or barrel. The movement of the abrasive mass in the working chamber is activated by a spinner plate located in its base, centrifuging it, and creating a vortex. Although cutting rates are high, surface protection is also high, the blades being completely encapsulated in the special ceramic abrasive media that is produced by Rösler, and travelling through it all at the same speed, in the same direction. The FKS is a double-batch finishing system, meaning that one batch of work is being processed whilst another is being separated from the abrasive media, the batch in separation will be washed on the screen area before feeding into a Rösler through-feed hot air dryer. The system programmes are controlled and monitored by a PLC. Process times will sometimes vary a little to take into account the surface start condition across blade families. It is however around two hours, and in this time a surface reading of 20 micro inches (0.5 micro-metres ) Ra or less will have been reached.SHOTBLASTING SYSTEM WITH ROBOTIC HAND The aerospace industries of the world probably more than any others use the technique of shot peening to re-introduce compressive stress into many of their components after forming or machining, lifting the fatigue strength, and considerably reducing the possibility of stress cracks appearing during their working life. A well known aero-engine manufacturer are no exception to this, and they themselves have considerable knowledge and expertise in this field, their engine blades, discs, shafts all being peened at some stage in their production cycle. Rösler are rightly proud that over the past few years they have played a major role in the development of peening machines and processes now used in the aerospace industries. The main advantage of a robotised system is that once all the critical times and settings of the blades in the blast stream have been determined and set, such as, angles, distances, coverage velocity, etc then the process is infinity repeatable. A further important advantage is that many aero engine blades require masking in certain area during peening or blast cleanings. It is possible with a robot system to sometimes design the tooling to mask these critical areas.

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