Ravi Karumanchiri wrote:That's quite a statement, and I'd like to elaborate: The problem with the pull of the moon messing with the alignment of your manufacturing process is indeed a significant one *particularly if you're working in machined metal*, like with the Eurofighter. By comparison, the Tejas LCA is constructed of epoxy-reinforced composites that are not machined the same way metal is, but rather, through a process known as "vacuum forming", wherein the pull of the moon should not be such a factor, owing to the inherent gravity-defying process stresses intentionally imparted with negative pressure (which would counteract a "sag" naturally, probably without laser-corrected jigs).
Its not manufactured at Warton, its assembled there. Component production including metal cutting takes place at Samlesbury.
As I understand it, the Rafale has a high proportion of composites too, whereas the Eurofigher makes more extensive use of exotic metals (that are much more expensive and difficult to machine than composites, which are 'machined' through vacuum forming processes, not slow-moving, expensive-to-operate CNC machines).
I wasn't aware of that. It was my understanding that the Eurofighter did extensively employ composites (by which I assumed the reference was to carbon composites), comprising of upto 85% by surface area.
From the site mentioned before -
Several large engineering production machines are now installed or projected to be used at Samlesbury. These include four Advanced Contouring Machines (ACM), two five-axis machining centres (FAM), an advanced 10-axis, gantry-type V4 Contour Tape Laying (CTL) machine. The levels of production accuracy required are astounding, panels and fittings have tolerances equal to 70 microns. This means that parts taken from one aircraft will fit any another, without modification, as was common practice on previous aircraft.
Key to production work at Samlesbury are two, five-axis FAMs coupled together with laser tracker systems. These machines allow the building of assembly jigs without the need to manufacture original master templates or gauges, reducing cost and increasing productivity. To ensure the jigs produced by the FAMs are indeed accurate virtual simulation has been used to validate the machining process. This facility also has three Mitsui Seiki five-axis horizontal machining centres which form part of the machining capability for smaller detail parts.
The V4 (version-4) CTL ordered in June 1999 from Cincinnati Machine of the United States is being used to automate the production of the composite structures. The core purpose of the CTL is to automatically heat and lay the thermosetting composite tape over a pre-defined shape or tool. The machine is able to cope with both flat and contoured (or combinations of both) tools enabling the complex curves and edges of various Eurofighter parts to be followed precisely. The CTL even automates the moving and positioning of tools for subsequent lay-up of the composite material. To support high lay-up speeds and large part capability the version-4 CTL provides 12.8 m X-axis longitudinal travel and 4.2 m Y-axis traverse. It is equipped with 635mm diameter reels providing 800 to 900 m of tape. The CTL should lead to improvements in quality and reduction in production times compared to older, manual lay-up methods.
Another substantial investment is a 14 tonne, 11.5 metre high column that has been installed to support a £7.5 million drilling machine in shed four at the site. The computer controlled machine will be used to automatically drill a thousand holes in each Eurofighter front fuselage. This is one of six such machines being installed in the site as part of an investment of around £35 million. This work was previously done by hand and the new system will enable much higher throughput while also producing one of the most accurate load bearing panels on any modern aircraft.
The setup for the Rafale is probably similar, though it may not be as geared for high volume production due to lower expected volumes. Either way, this would be a truly rewarding opportunity for HAL only if it can carry forward relevant sections of the technology, to other aircraft programs.
