Hi Pat and Phil, Thanks for your thoughtful replies, they are quite reassuring. This gives me some information to keep in mind for the next time I get the chance to talk to a higher level NASA director. If the auto industry went metric because it made good business sense, then it probably makes good business sense for NASA to follow their model. I already can see how true this would be for my own work.
John On Sunday 05 October 2003 20:51, Phil Chernack wrote: > Here is an example of a NIST program to improve tolerances and fit and > finish in automobile manufacturing. No mention of IPF anywhere. Correct > me if I am wrong, but as far as I know, auto manufacturing in the U.S. has > been predominately metric since the late 1970s. > > "Developed with the support of NIST's Advanced Technology Program (ATP), > the "2 millimeter" assembly process is credited with improving both vehicle > quality and customer satisfaction." > > http://www.nist.gov/public_affairs/factsheet/abc2.htm > > Phil > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Behalf Of Pat Naughtin > Sent: Sunday, October 05, 2003 9:55 PM > To: U.S. Metric Association > Subject: [USMA:27113] Re: Metric usage in engineering > > > Dear John, > > Clearly our experiences differ. My examples were largely drawn from > Australian examples of companies, from the USA, and their practices in > Australia. > > I have interspersed some remarks. > > on 6/10/03 10:12 AM, John S. Ward at [EMAIL PROTECTED] wrote: > > Hi Pat, > > > > Unfortunately, information shared on this forum regarding metric usage in > > the > > > automotive, aerospace, and electronics industries does not match my > > experiences. I would love to see a more comprehensive write-up with > > sources > > > and examples to back up the claims made by metric advocates. > > > > To summarize my experiences: > > - Inches totally dominate for length, except for microscopic scales > > Here, millimetres dominate. In the automotive industry, inches are rarely > used, or referred to, except as replacement parts for older models. I live > in Geelong, which has had a large Ford factory since the 1920s and I > regularly meet engineers and factory workers from Ford. They report that > they only see drawings in millimetres, that they only work in millimetres, > and that they very rarely see reference to inches (and never to > centimetres). > > My brother in law is an engineer at the Toyota factory in Melbourne and he > tells me that conditions there are the same as at Ford in Geelong. All > designs, all drawings, and all construction is done using millimetres > usually to a precision to 0.1 millimetres (for the panel work that is his > speciality). > > > - Superstar scientists and engineers think and work in metric. > > Work-horse > > > engineers think in inches. Somewhere between the superstars and work > > horses, > > > designs end up hard inch-pounds. > > For 12 years I worked with the Australian Commonwealth Scientific and > Industrial Research Organisation (CSIRO). Generally, the science was done > using metres and millimetres, but some groups preferred to use other > measures of length such as angstroms, centimetres, microns, and > millimicrons (the only people who ever used inches were the cotton > researchers who worked closely with USA cotton researchers); choice of > units seemed to depend on the social power structure within the group of > scientists and their need to use jargon to preserve their special status > within the group. > > I worked in various sections of CSIRO. Those nearest the engineering end of > the spectrum (forests and forest products, mechanical engineering, and > solar energy) worked almost purely in metres and millimetres. Those who > were further away (cotton, leather, textiles and wool research) tended to > have a mishmash of units including angstroms, centimetres, inches, microns, > and micronaires. > > When scientists require specialist equipment, all designs are made in > millimetres, all drawings are done in millimetres, and the workshop > craftsmen all use millimetres exclusively. The only exception to this rule > is for replacement parts for old machinery. > > An interesting side issue to this is the occasion that I had to explain to > a workshop foreman that a micron was really a micrometre. The workshop > staff had been building a device to measure the diameter of wool fibres > (typically 15 �m to 40 �m) and the scientists had never explained that the > scientist's jargon word, micron, had a physical reality. 'Oh', said the > machinist, 'is that all it is � I thought it must have been some kind of > scientific magic that I wouldn't understand and so I was afraid to ask'. > > > - Metric units are used frequently for mass, temperature, power, and > > volume > > Metric units are always used for 'mass, temperature, power, and volume' > with the exception that sometimes an engineer will use the expression > 'horsepower' when they want to compare a new engine with an old one. > > > - Metric units are used exclusively for electrical properties (volts, > > amps, > > > ohms, etc.) > > Ditto. > > > NASA / Aerospace: Inches are completely dominant in engineering design. > > Almost all parts are designed and made hard-inches. NASA is more metric > > than > > > the defense department and private industry, and continues to use > > inch-pounds > > > in part because industrial partners have a hard time dealing with metric. > > Hardware involving astronauts is almost 100% non-metric. > > Did I have it wrong? I understood that Werner von Braun had always designed > in metric. > > > The lab where I > > work (JPL) is the most metric NASA lab. Probably less than 30% of all > > parts > > > are designed all metric (the rest are designed in inches) and even parts > > designed in metric are often converted to inches for machining. Note > > that JPL engineers are practically all bilingual, and everyone mixes > > units depending on the context. > > Do you have any idea of the costs of being 'practically all bilingual'? How > much does the time cost when 'even parts designed in metric are often > converted to inches for machining'? > > > Electronic industry: Most lengths, designs, and wire sizes are in > > inches. Everyone uses SI units for electricity: volts, amps, ohms, > > henries, > > farads, > > > etc. Temperature is specified in Celsius for some things and Fahrenheit > > for > > > others. The really high-tech stuff (integrated circuit chips and some > > microwave engineering) are done metric. Everything else, however, is > > inches. > > > Electronic parts sizes are all specified in inches. Circuit boards are > > laid > > > out in inches. Wire sizes are specified in American Wire Gauge or > > inches. > > What a mess! The only time that I have seen wire gauges in recent years was > when I worked with Australia's only piano maker on his design for a new > (2.9 metre) grand piano. When he wanted to buy piano wire he was confronted > with all the world's confusion of wire sizes; I suggested that he ask the > wire manufacturers to specify each wire in micrometres so that he could > compare them � after they did this, comparisons and calculations were easy. > > > Auto industry: I have a friend who a few years ago worked on air bags > > for > > the > > > American automotive industry. He says his work was 100% inches. Not > > metric. > > > I've seen claims that the auto industry is metric, but I haven't seen any > > good references or documents to back up this claim. What fraction of > > drawings at Ford or GM are in inches, and what fraction are metric? I > > would > > > also like to take a walk through an automotive machine shop and see how > > things are made. > > For a fact, Toyota in Melbourne is all metric. From hearsay, I have deduced > that Ford, in Geelong, is all metric. > > > I've spent an awful lot of time working in a variety of > > science/electronics > > > oriented laboratories. Here are a few observations: > > Fasteners (screws, etc.) inches completely dominate > > Here they are a mixed bag. Metric sizes are generally preferred by original > equipment manufacturers, and old sizes are available for the repair market. > Sometimes these two areas overlap. > > > Tools: Mostly inches > > Mostly millimetres, but inch sizes are available. > > > Almost all parts are measured in inches > > Almost all parts are measured in millimetres. > > > Breadboards, optical benches, etc.: All inches > > Don't know. > > > Volume: Usually measured in ml or liters > > Always measured in millilitres, litres, and if large enough, kilolitres, > megalitres, and gigalitres. > > > Mass: Usually metric > > Always kilograms or tonnes. > > > Force: Mostly pounds > > Forces are specified in newtons, kilonewtons, and meganewtons, but pounds > force (lbf) is also still used to compare with old mindsets. > > > Torque: Mostly ozf in, lbf in, or lbf ft > > Torque in newton metre is common in vehicle construction and is also common > in automotive magazines. However, some magazine writers are still using > lbf ft for comparison with old vehicles. > > > Pressure: PSI, atmospheres, or Torr (Never pascals or bars) > > Pressure in pascals, kilopascals, and kilopascals is the norm, with > lingering traces of psi, and very occasionally atmospheres. > > > Temperature: Usually Kelvins or degrees Celsius > > Ditto. > > > SUMMARY: Inches completely dominate American engineering. Almost > > everything > > > is designed hard-inches. Consumer products are NOT dumbed-down for the > > public. However, except for length, other metric units are widely used. > > Summary: millimetres dominate Australian engineering. Almost everything is > designed, drawn, and built in millimetres. > > However, items from the USA commonly have their dimensions specified in > inches. As Han said, the 90 millimetre computer disk has been known here as > the 3 1/2 inch disk. To us this looks a lot like dumbing down. > > Cheers, > > Pat Naughtin LCAMS > Geelong, Australia > > > On Sunday 05 October 2003 04:58, Pat Naughtin wrote: > >> Dear John, Han, and All, > >> > >> Front end down-dumbing > >> > >> There are a number of areas where an entire industry is metric and � > >> just before release to the public � there is a dumbing down by the > >> marketing/media department for the public. > >> > >> I will call this 'Front end down-dumbing'. > >> > >> Let me give you some examples. > >> > >> The world motor industry > >> In the 1970s the whole world motor vehicle industry changed to metric > >> measures. They did this to achieve massive savings by adopting the > >> 'world car concept' where component parts could be sourced from the best > >> priced parts anywhere in the world. Since the mid 1970s all � I'll > >> repeat that > > ALL > > >> � cars in the world have been made using only metric measures. There are > >> about 10 000 parts in a car and each of these needs on average 10 > >> measurements � making 100 000 measurements in all. In the USA the car is > >> then fitted with its down-dumbing equipment, a speedometer labelled > > 'mph', > > >> and odometer labelled 'ml', and a tyre labelled 14. These three labels > > are > > >> generally sufficient for the new car owner to believe that they are > > driving > > >> an 'English' designed, and 'English' built, and that all is right in > >> this 'English' world. Note that this is three labels (not measurements) > >> out of 100 000 or 99.997 %. Apparently 0,003 % is enough to convince the > >> public > > of > > >> the 'truth'. > >> > >> NASA > >> As I understand it, but please correct me where I'm wrong, NASA has two > >> classes of programs: the heritage programs designed in metric (by Von > > Braun > > >> et al) and then converted and specified in feet and inches for the US > >> engineers to build them, and the more modern programs designed in > >> metric, specified in metric and built in metric. Once a program is under > >> way the data is then given to the down-dumbing department (probably > >> called something like NASA Public Relations) where all the data is > >> converted to 'English' values for press releases, 'English' values for > >> web-sites, 'English' values for political speeches and to generally give > >> the > > allusion > > >> that NASA is completely 'English'. > >> > >> Computer industry > >> The research done on my computer to design the chips was done using > >> nanometres, the silicon masks were then designed using micrometres, the > >> component parts were then designed and built in millimetres with a > >> precision to the nearest tenth of a millimetre. Then this data was given > > to > > >> the down-dumbing department (in the USA) who then dumbed it down to > >> 'English'. I believe that every part of every component in my computer > > was > > >> designed and built using metric units; it wasn't until the > > marketing/public > > >> relations people became involved that the down-dumbing took place. > >> > >> In these three examples, it's interesting to note that the down-dumbing > >> only occurs at the interface between the company and the public. The > >> companies involved would not consider going back to old measures at all > >> � ever � the costs would be far too great. But they will tolerate the > >> down-dumbing process. Maybe management of these enterprises does not > >> believe that running whole down-dumbing departments is costing them > >> anything. > >> > >> Cheers, > >> > >> Pat Naughtin LCAMS > >> Geelong, Australia
