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Emerald Group Publishing Limited
Copyright © 2000, MCB UP Limited
Plane makers on top of the world with System 3R
Plane makers on top of the world with System 3R
Keywords: System 3R, Palletising, Aerospace industry
Precision and speed are vital prerequisites of today's aerospace manufacturing industry. Consequently the leading players around the world are consistently moving forward with new engineering technologies that save time and money, ensure repeatable accuracy but which do not compromise on quality.
A leading supplier of robust, high-tech workpiece handling systems for plane makers is System 3R. Their advanced palletisation systems, which have undergone some remarkably stringent controlled and authoritative laboratory tests and have come through with "flying colours", have proved they can more than competently do the job. What is more, they can also dramatically reduce set-up times from days and hours to literally minutes! And, of course, the productivity advances that can be achieved by the latest System 3R robotics capabilities also make a substantial impact on the bottom-line.
In the UK at BAe's Chadderton plant near Manchester, they are making the J-spars and C-spars for the latest Boeing aircraft in conjunction with a Cincinnati Milacron CNC machine. Ten huge handling pallets measuring 6m x 4m and weighing 8 tonnes each, making this probably the world's largest machine tool palletisation system, are being used to great effect.
There are always two pallets on the 20m-long machine bed while the other eight are loaded in the pre-production bay. System 3R's Zerofix provides speedy, fool-proof off-line set up for the workpieces using a unique x, y and z reference system which always ensures accuracy to within a few microns.
The machine bed is 4m wide with three vertical heads across its width. Pallets are placed on two at a time using a massive gantry crane that straddles the entire operation. The traditional way of setting-up the pallets would have taken engineers many hours, but as System 3R's Zerofix works on only one primary and one secondary fixing point, it has reduced set-up time to a matter of minutes.
As a result, efficiency is maximised, production interruptions are minimised, and hence productivity is 45 per cent greater. Understandably the concept won a prestigious British Aerospace Silver Award for innovation, based on the principle that the machine never stops, and so its utilisation is dramatically increased.
Rolls-Royce Engines in Derby are also using System 3R Zerofix pallets and chucks in the production of both Airbus and Boeing engine parts. This has so improved holding capabilities that each engine's sections can be pre-set outside of the milling machine and then the entire unit dropped on to holding chucks.
The casing and stator machining process takes place on two new Mazak Megaturn CNC machines operating within a specially-built dust free "cocoon" with a high efficiency air conditioning system to maintain a constant 20°C temperature.
The production process uses a total of 20 circular Zerofix pallets each 1.4m diameter, supporting a fixture. Two offset steel pins ensure quick basic pallet alignment to the table chucks while the Zerofix chucks themselves locate and clamp the pallets to within 0.010mm. There are different pallet fixtures for different casings and their maximum overall weight is up to 3 tonnes when fully loaded. While two pallets are on the machines, the other pallets are being set up thus, once again, maximising machine running time.
One of the most popular machining centres in aerospace production is the Modig ProfileLine because it is cost-effective, and with built-in System 3R Zerofix pallet systems and WorkManager software its lead-times have been reduced by 75 per cent. So it is no small wonder that major aerospace manufacturers such as Boeing, McDonnell Douglas and Raytheon have all invested heavily in them. In fact, Boeing presented Modig with their Outstanding Performance Award, one of the aircraft industry's most prestigious accolades.
Because working methods vary from manufacturer to manufacturer, Profile has a high degree of inherent flexibility. And although it weighs 6 tonnes its footprint is relatively small. Yet one machine is currently machining profiles up to 15m long by an interchangeable spindle at speeds up to 45,000 rpm.
Modig Group machines also feature in the SAAB Aerospace Swedish/British Gripen project where they are using large numbers of Jungner Crest-Cut milling cutters for the complex-shaped parts that are mainly of aluminium, although steel and titanium also play a big part. The cutters have to be extremely sharp, so after every batch the tools are returned to the company's machine tool workshop for sharpening.
Initially this operation was carried out manually and therefore success depended principally on the experience of individual operators and their ability to turn around the sharpened cutters as quickly as possible with a precision finish. The alternative was to create a fully-automatic grinding cell based on state-of-the-art robotics, which would place less dependence on operator skills, consistently provide identical cutters and also create the facility for efficient round-the-clock production.
SAAB's engineers realised that this could not be achieved by any piecemeal approach and concluded that the grinding machine and the robot would have to be supplied as a complete cell from a single supplier. As they had good experience of Modig Group companies, the machine they decided to run with was a Junger US-630 CNC.
It was equipped with System 3R's automatic Macro-chucks in both the work-head and the grinding spindle, as well as a WorkMan robot with three magazine disks providing 22 positions, making 66 positions for the milling cutters, as well as a disk with ten positions for the grinding wheel packages. A System 3R WorkManager cell computer controls both the robot and the grinding machine process.
After random loading of the magazine, either manually one position at a time, or by lifting in entire ready-equipped magazine disks, the work cycle starts by scanning all magazine positions. The cell's computer identifies each individual object, determines its position in the magazine, and fetches the information keyed in at the loading station.
The WorkManager software also checks that both the chuck with cutter and the necessary grinding wheel package are loaded in the magazine and this is displayed on a screen in order of projected completion. Priority can be changed if necessary.
The automatic cell is then started and all jobs in the magazine are carried out in order of priority. The 66 positions in the magazine correspond broadly to the capacity of the machine during a night shift, and when the morning shift arrives all that is needed is to empty the magazine and harvest the results.
MG Instruments is also closely involved with the Gripen project, as well as the European Ariane project, producing complex components from sophisticated materials, and all subject to extremely stringent demands on dimensional accuracy and surface finish. So they would find it difficult to meet their commitment to the aerospace industry were it not for modern engineering techniques and their use of high-speed milling.
MG's most recent additions are two Matsuura 40,000 rpm machines, which means that they now have access to ten high-speed machines. But their high-speed milling potential would be somewhat diminished if the machines were standing idly by during lengthy, non-productive setting-up operations.
Indeed, MG would be the first to agree that minimising set up times very quickly justifies the investment in a reference systems such as System 3R's 3Refix. Now their machine operators always insist on "no new machines without 3Refix accessories". MG has over 100 3Refix cubes, both four- and six-sided, to help them maximise their machines' production times.
Proud at Turin
And at the Turin plant of Fiat Avio where aircraft engines are made, they are using System 3R's Macro Magnum pallet system in conjunction with two-gear hobbing machines. This has reduced set-up times by as much as 75 per cent, which means they have doubled their existing machining capacity.
In the USA, at its plant in Scarborough, Maine, the Rich Tool and Die Company has 48 EDM machines dedicated to producing precision parts such as turbine nozzles from the toughest materials including Inconel 718, cobalt based alloys, stellite, waspalloys and titanium.
Nozzles are a critical engine part that compress high volumes of gas and direct them on to the rotor blades, so they have to withstand immense combustion heat. Their design is often complex and varied, also they are made from high strength single crystal materials that do not take too kindly to standard machining methods; hence EDMing is the principal solution.
Also most of the parts the Rich Company produces or builds fixtures for are unconventional geometric shapes that make them difficult to hold accurately in conventional chucks. So in addition to using System 3R's pallet style EDM tooling, the work tables of several of their sinker EDM machines have large 3Refix plates with a precision grid of 20mm diameter jig ground locating holes. By using expanding dowel pins to position special work holding fixtures, precise set-up is achieved in just a few minutes.
Like every progressive aerospace industry manufacturer, the Rich Company has to consider all new engineering technologies in order to meet current demands and keep pace with the challenging developments that it will meet in the future which are waiting around the New Millennium corner. It has therefore identified, in common with these other manufacturers mentioned, a link to help them achieve these demanding objectives by forging an ongoing relationship with System 3R world-wide, that will endure well into the century.