THE GLOSSARY!

Use this thread to post or seek explanations of engineering words, phrases, abbreviations and acronyms.

If the thread fills up with a useful selection, I will use it to prepare a short glossary for beginners to go in MEW.

Posters should be aware it won't be practical for make to acknowledge individual postings in any subsequent article so if you don't want to see your unattributed definition in print, don't post it!

I'll start with three examples from recent articles. If you use a similar format I can cut and paste into the MEW glossary!

Feel free to use the thread to discuss and debate terms as well.

PCD - Pitch Circle Diameter, the diameter of an imaginary circle which is used to position holes, gear teeth or anything else arranged around its circumference.

OD - outer (or overall) diameter

BDMS - Bright Drawn Mild Steel - steel prepared by pulling it cold through forming dies. It may distort when machined due to locked up stresses.

**LINK**

Rik

Here's 2 useful ones:

UTLA Useless Three Letter Acronym

MBA Means B*gger All (it's actually a qualification in management babble)

Nice idea for a short while. The ones we tried to assemble at work soon became cluttered with abbreviations and acronyms that were only used very occasionally. Rather like the ones in Rik's link.

JA

Shouldn't be a problem if the Glossary is managed by a professional editor. Can anyone suggest a suitable candidate?    ( I feel bad about that ghastly smiley. Chaucer, Shakespeare and Dickens all managed perfectly well without Imoji. Oh well, one must move with the times.)

I think a Glossary is a good idea: we beginners need all the help we can get. And don't forget I have a terrible memory.

Humorous definitions could go into a Devil's Dictionary for publication in April. I'm sure I could explain "Wedding Tackle" if someone reminded me!

Dave

Edited By SillyOldDuffer on 10/11/2016 13:58:03

Here's a trivial point that's been confusing me this week.

I'm OK with Hardness, Toughness and Brittleness, but what's the difference between Malleability and Ductility that makes it possible to be one without the other?

Dave

I'm expecting this thread to descend into the usual chaos (it seems to have already, i see very few definitions...) I will extract any nuggets and make an unrecognisably neat and sensible neat page or two for the magazine.

For those who can't wait there's always the Home Workshop Dictionary

Malleability is the ability to be formed into a new shape, ductility is readiness to change shape under stress, so very similar, but not quite the same thing. I think ductility relates to being 'pulled' whereas malleability is about being 'pushed' or forged.

Neil

I have never met a metal that only possessed one of these two properties. The classic stress strain curve just says that the metal yields above a certain stress. The yielding can take any form including ductile and malleable.

I do wonder whether I have missed something here.

As for the Glossary, I had putting in my previous posting that someone would have to edit it. Then I decided to remove the comment because I thought Neil was volunteering to do that!

JA

Edited By JA on 10/11/2016 15:38:14

Ductile is always malleable, but malleable isn't always ductile. Some things can be beaten or pushed into a new shape, but are too brittle under tension to be ductile. As an extreme, think of trying to draw silly putty into a wire - it always snaps when pulled.

My thinking was identical to JA's: "I have never met a metal that only possessed one of these two properties" and "I do wonder whether I have missed something here"

I got hung up on the properties of Copper. The Silly putty example is much better: it makes the difference clear.

Thanks

Dave

Being a junior Dr Johnson is hard work!

Cast Iron. A range of about 30 different high carbon/iron mixes, very fluid when molten and good for casting. Different variants are used to make Brake Blocks, Engine Blocks, Machine Tools, Pipes and Street Furniture etc. Quality ranges from very poor to very high. Easily machined except liable to have a very hard outer skin, very dirty, no cutting fluid needed. Strong in compression, weak in tension.

DTI : Dial Test Indicator. An instrument used to measure small distances (0.01 to 0.005mm). Used to accurately position work and to test the roundness, droop, or deflection of a work piece.

EN1A (aka 230M07). A type of Mild Steel suitable for machining general purpose components to a good finish. Low tensile strength (for a steel). Cannot be heat-treated. May be case hardened.

EN1APb. As EN1A but softer and more easily machined. Must not be welded.

Work Hardening. A phenomenon whereby a material becomes harder and more difficult to machine as it is worked. Some stainless steels can become harder than the tools being used to cut it. The problem is exacerbated by over-gentle cutting or blunt tools.

Lathe. A metal working machine that cuts by rotating the work against a fixed cutting tool.

Mill. A metal working machine that rotates a cutting tool against a fixed work piece.

Reamer. A tool used to finish a drilled hole to an exact size by removing a small amount of metal.

MT2. A specification for a wedge tool holder. A male shank on the tool is tapered to fit into an equivalent female socket, for example a lathe tailstock. The wedge action of the taper stops the tool rotating whilst still allowing it to be pulled out and exchanged.

Plutonium. Silvery-white metal. Radioactive, hot, highly toxic and highly reactive. Critical mass about 10kg (a 100mm diameter sphere) Used in the boiler of an enhanced LBSC 'Tich' being built by Guy Martin for the 2018 IMLEC

As a former newspaper editor, the use of acronyms by reporters used to drive me nearly mad, and I eventually had to ban 99 per cent of them because, to the average reader, they meant nothing. The same goes in engineering - please only use acronyms when they are so well known that everyone understands them, or space is so restricted that there is no alternative.

Last year at this time I attended a conference of a medical charity for which I am a volunteer, and three successive speakers used strings of weird acronyms known only to a small minority of health professionals. At the end, when filling in a suggestions form, all I felt I could write was "Make the use of acronyms a hanging offence." The annual event is tomorrow, and I am wondering if my suggestion has been taken seriously.

Please, please, let us use the Queen's English whenever possible!

Bare and Full as used by Martin Evans on his drawings meaning minus a bit and Plus a bit.
Some form of reference to the ISO limits and fits and where to find them (H8/f7 for a hole bases running fit)

Can I suggest an extension of this idea? Names of machines, and their parts, with illustrations keyed with letters or numbers. For example, a car might show the bonnet and bumper (among lots of other stuff) which terms are not known in foreign parts,. Given the letter code, our friends in the USA, Australia, etc etc, could compile their own listings. In my example, we would find hood and fender from the USA, but what are they called in South Africa or the Windward Islands?

I'm sure that readers would find such stuff helpful in understanding the articles in ME and MEW which do sometimes fail to explain things as they go along*. And how long before we could have a glossary of the bits and pieces we work with in lots of different languages, all keyed to the same pictures by code letters. And most of the pictures exist already, in old copies of ME, etc.

Just a thought for the long winter evenings.

I have the latest ME on my desk. The Contents list includes these terms:

Tandem Compound (something you rub on a poorly bicycle?)

Lampless Oil (non inflammable lubricant?)

Well Tanks (go on, you have a go ...)

I am not saying that the Contents list is wrong, but don't beginners need to be able to look things like this up?

Cheers, Tim

I will try to add a few suggestions:

Neat cutting oil - A cutting oil that is used without addition of water (a mistake I made once).

High speed steel - A tool steel that can withstand local high temperatures. The only way to machine it is by grinding. Not suitable for heat treatment.

Carbide tool - A tool that is made from ??????? carbide. Can be shaped using a ?????? grinding wheel. Its cutting speeds are greater than high speed steel (my knowledge runs out here).

Cutting speed - The speed of the cutting tool against the work piece. Usually expressed as RPM (revs per minute) for a given diameter but should really be given as a velocity ie. m/s (metres per second).

And so I could go on.

JA

Edited By JA on 10/11/2016 19:33:43

Edited By JA on 10/11/2016 19:35:13

Its a fine line.

To a certain extent the use of 'in house' expressions is part of being 'one of us'.

This means that it can act to bind people together and helping people understand these terms can actually help newcomers feel part of a wider 'fellowship'.

Equally, if they are left struggling it can make them feel excluded.

Now and then I will do a small edit to help make sure a beginner can work out an unfamiliar term from the context, but I think a short 'cut out and keep phrasebook' could be a useful thing to print, and it could then become a permanent page on this website.

From working on the dictionary I know it's literally weeks and weeks of work to compile something comprehensive, but I think that fifty to a hundred common terms would probably cover the main tripping points. What are the words or acronyms that YOU found confusing when you were a beginner?

Neil

I'm all for the Queen's English, though it's hard to keep up with whatever it is. People laugh at you if you call for a taximeter cabriolet.

The rule where I worked was to decode acronyms on first use, thereafter to use them because they made the paper easier to read. Allegedly. More often documents just turned into alphabet soup.

Even if we could wipe out new acronyms Neil has a historical justification for his Glossary. Smelly Hobbits have been writing and talking engineering jargon since the dawn of time. Where's the Rosetta Stone?

Dave

Just looked for your publication Neil, but is it only available as a Kindle and not in paper? If it is only Kindle I will get it anyway and put it on the Mac.

Being a self taught home engineer I never heard the language describing component parts as a trainee. Things like flange, pinion, detent, lug, journal are now obvious, but on first encounter you can struggle to work out what part someone is referring to. It needs a set of pictures labelling the areas being described. A few complex components could contain a lot of descriptors and help explain a lot.

Similarly, pictures of: a lathe, locomotive valve motion, a beam engine, etc., etc. could be fully labelled.

The Glossary idea has been started elsewhere, for example http://www.fluor.com/about_fluor/newsroom/pages/engineering_glossary.aspx#A

Norm

Here's possibly the world's worst acronym: REMAP.

Rehabilitation Engineering Movement Advisory Panel.

No wonder that almost nobody has heard or knows about it.