Does NC mean "national course" as in threads, or "numerical control" as in digital machine tools? I had to pause to realize the probable correct answer since you were discussing both fasteners and imported machine tools.
---- Original message ---- >Date: Wed, 8 Dec 2010 10:23:03 -0000 >From: "John Frewen-Lord" <[email protected]> >Subject: [USMA:49054] Re: Boeing and metrication >To: "U.S. Metric Association" <[email protected]> > > A good friend of mine is a professional engineer in > Ontario, working for a company that designs and > manufactures parts and sub-assemblies for mostly the > automotive sector but occasionally other industries > as well. Almost all of their work is in SI (as it > would be for the auto sector - GM, Honda, Toyota, > etc). His company was contracted as a third teir > subcontractor on the 787 to a major Japanese > company, in connection with detail design and > manufacturing of specific components relating to > assemblies such as undercarriage doors and the > like. They had two main problems: > > 1. All fasterners were imperial sized, and had to > be sourced from the US, as almost all fasteners in > Canada are metric - this caused some major delivery > delays, and in some cases they had to ship > components unassembled due to lack of fasteners. > > 2. All their NC machinery comes from Germany or > Italy, and is metric only. They had to convert all > Boeing's dimensions to imperial equivalents. While > for the most part they were able to get the > conversions within tolerances, occasionally they > were stretching these tolerance limits, and if the > limits became cumulative instead of cancelling each > other out, then there was some work that ended being > significantly out of tolerance. > > I seem to remember when the 787 was first announced > that Boeing was 'pround' to keep its airliners in > USC units. Just quite why they then subcontracted > most of it to an almost totally metric-only world > beggars belief. Yes, Europe and the rest of the > industrialized world does occasionally have to deal > with non-metric work, but it is by exception > usually, and always costs more, in terms of both > time and money. > > Will Boeing have learnt its lesson in this? I doubt > it. I predict when they start on their next > airliner (likely a replacement for the 737), they > will keep to USC and not subcontract any more than > they have to. Airbus will no doubt be very happy. > > Finally, if anyone has any doubt that working in > imerial/USC costs more than metric, most Canadian > arhictects and engineers charge more to produce > drawings in imperial - on one project I worked on, > where a whole existing (imperial) hospital was being > digitized, the bill was going to be 10% higher if we > retained the original imperial dimensioning rather > than convert to SI! > > John F-L >...
