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 µm to 40 µm) 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 >
