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Now, see, this is what I love about off-topic... There's so many people
here who know interesting stuff! :-D
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> I wonder if they use something like the acid on "frosted" glass...
There are both mechanical methods and chemical etching methods to make the
patterns. Basically you are just making a pattern on the surface of the
metal in the mould. For one of our plastic products (which is an optical
component so is transparent plastic) they make "fine adjustments" to the
surface texture by some dude manually "roughening up" the surface in certain
positions :-)
> Yeah, well, that's a function of far more than the plastic shell. Gotta
> assemble the whole thing for that! ;-)
Usually you don't do any testing on individual parts, only on the assembled
product.
> Apparently by dad spent some time working in a plast where they do "vacuum
> forming", and each time you do that, you have to cut a bunch of wasted
> plastic off the edges. He says they sent it back to the suppliers and they
> got a discount. (But then, how hard can reprocessing a flat sheet of
> plastic be?)
Well yeh, if from every single shot you have some waste then it makes sense
to work out how to reuse that. But working out how to reuse 5000 samples is
a bit pointless if you are planning to make 2 million every month later.
> And that brings us back to my question about components which are supposed
> to "snap together". I guess it depends on how deformable the plastic is?
> (And that surely must depend on shape...)
Yep, or technically "stiffness", which is how much something deforms for a
given force (units DISTANCE/FORCE). You can of course design the shape so
that things deform easily for clips, or make springs to hold things in place
etc.
> It kinda makes you wonder how anything ever gets made in the first place!
Yeh I often wonder that too...
> Heh, and I bet that's even *more* damed expensive again... not to mention
> the quality hardened steel you need for it to mill...
And then the actual milling bit, which presumably must be harder than the
hardened steel :-)
> I wonder... do companies buy all this stuff themselves? Or just
> subcontract it out?
Well you get quite long supply chains sometimes, like take for example car
company 1. They will have supplier 2 that makes some big chunk of the
dashboard. Supplier 2 will have a supplier 3 that provides one part (eg the
radio). Supplier 3 will then use supplier 4 to make the plastic part to go
on the front of the radio. Supplier 4 will own the injection moulding
machine, but could well use a supplier 5 to actually manufacturer the tools
to go in the injection molding machine. And of course there will be another
supplier 5 that supplies the raw plastic to supplier 4.
Companies like Nokia and Ford don't actually make much, they just design
things and get other people to make them, then assemble bits together :-) I
once saw a Nokia factory, each production line was about 50 metres long,
they simply screwed some components together, did some electrical and
optical testing, clipped the plastic parts on and packaged it into several
layers of cardboard boxes. Very low tech and very simple.
> I also wonder... Today we have machines that make components of machines
> that are used to make machines for making machines. Some of this stuff is
> made to absurd tolerances - stuff no human could ever make by hand. So...
> how the **** did we make it in the first place?!
Well just because you only have equipment to design and make stuff to
tolerance X, it doesn't mean that you can't make a machine that can make
stuff to a tolerance lower than X. eg you could just build a motor and then
gear it down a lot so that the movements are very small and accurate, or use
optical lens to shrink your design, or use a lever so that a larger
tolerance on one end corresponds to a smaller tolerance at the other end.
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scott wrote:
>> I wonder if they use something like the acid on "frosted" glass...
>
> There are both mechanical methods and chemical etching methods to make
> the patterns. Basically you are just making a pattern on the surface of
> the metal in the mould. For one of our plastic products (which is an
> optical component so is transparent plastic) they make "fine
> adjustments" to the surface texture by some dude manually "roughening
> up" the surface in certain positions :-)
Yay for manual roughening up dude! :-D
>> Yeah, well, that's a function of far more than the plastic shell.
>> Gotta assemble the whole thing for that! ;-)
>
> Usually you don't do any testing on individual parts, only on the
> assembled product.
Not even to test that they actually fit together properly? Or is that
more or less guaranteed before the parts leave the design stage?
(OTOH, I guess that assembling the final item *is* checking that the
parts fit! :-D )
> Well yeh, if from every single shot you have some waste then it makes
> sense to work out how to reuse that. But working out how to reuse 5000
> samples is a bit pointless if you are planning to make 2 million every
> month later.
OK, fair enough.
>> And that brings us back to my question about components which are
>> supposed to "snap together". I guess it depends on how deformable the
>> plastic is? (And that surely must depend on shape...)
>
> Yep, or technically "stiffness", which is how much something deforms for
> a given force (units DISTANCE/FORCE). You can of course design the
> shape so that things deform easily for clips, or make springs to hold
> things in place etc.
IIRC, if you bend plastics they return to their original shape, until
you bend them past a certain point, at which they deform permanently.
(They also change colour for no adaquately-explored reason...)
>> Heh, and I bet that's even *more* damed expensive again... not to
>> mention the quality hardened steel you need for it to mill...
>
> And then the actual milling bit, which presumably must be harder than
> the hardened steel :-)
HOW THE HELL DO THEY CUT DIAMONDS?!
>> I wonder... do companies buy all this stuff themselves? Or just
>> subcontract it out?
>
> Well you get quite long supply chains sometimes, like take for example
> car company 1. They will have supplier 2 that makes some big chunk of
> the dashboard. Supplier 2 will have a supplier 3 that provides one part
> (eg the radio). Supplier 3 will then use supplier 4 to make the plastic
> part to go on the front of the radio. Supplier 4 will own the injection
> moulding machine, but could well use a supplier 5 to actually
> manufacturer the tools to go in the injection molding machine. And of
> course there will be another supplier 5 that supplies the raw plastic to
> supplier 4.
>
> Companies like Nokia and Ford don't actually make much, they just design
> things and get other people to make them, then assemble bits together
> :-) I once saw a Nokia factory, each production line was about 50
> metres long, they simply screwed some components together, did some
> electrical and optical testing, clipped the plastic parts on and
> packaged it into several layers of cardboard boxes. Very low tech and
> very simple.
Heh. That explains why if you drive round any small industrial estate,
you'll find some nobody company that's never been heard of called
"Lanstead Way Plastics Ltd" or something. They all mould plastics! :-D
>> I also wonder... Today we have machines that make components of
>> machines that are used to make machines for making machines. Some of
>> this stuff is made to absurd tolerances - stuff no human could ever
>> make by hand. So... how the **** did we make it in the first place?!
>
> Well just because you only have equipment to design and make stuff to
> tolerance X, it doesn't mean that you can't make a machine that can make
> stuff to a tolerance lower than X. eg you could just build a motor and
> then gear it down a lot so that the movements are very small and
> accurate, or use optical lens to shrink your design, or use a lever so
> that a larger tolerance on one end corresponds to a smaller tolerance at
> the other end.
Yeah, but without precisely machined gears, wouldn't there be too much
play between the teeth for the position to hold accurately?
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Invisible wrote:
>> A typical hard-tool for a simple plastic part (eg the front cover of
>> your CD drive or half of a simple keyboard shell) will cost of the
>> order of 10-40k pounds.
>
> o_O
>
> Ouch...
Pff.. That's nothing :) The jigging system I worked on cost about US$1M
for a decently sized system. ~US$100K per 4 axis table. Our saws ran
about US$100K-250K
I'm guessing Injection molding machines don't have computer controls.
I'd imagine the engineering costs are pretty high, though ... getting
all of the pathways right so the part fills the mold properly, and cures
properly.
> Perhaps I should clarify: I'm talking about a "keyboard" of the musical
> kind. Somebody might attempt to put it on a stand that only supports the
> ends of the unit, and it's over a meter wide. (Even so, all it contains
> inside is a circuit board. No batteries or power supply or anything
> heavy, just the key action.)
>
My el-cheapo Casio has a metal chassis. Ask me how I know ... I had to
pull it apart to fix the MIDI out port ... stupid thing came un-soldiered.
--
~Mike
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>>> A typical hard-tool for a simple plastic part (eg the front cover of
>>> your CD drive or half of a simple keyboard shell) will cost of the
>>> order of 10-40k pounds.
>>
>> o_O
>>
>> Ouch...
>
> Pff.. That's nothing :) The jigging system I worked on cost about US$1M
> for a decently sized system. ~US$100K per 4 axis table. Our saws ran
> about US$100K-250K
Jig system?
What are you trying to cut? Kryptonite??
> I'm guessing Injection molding machines don't have computer controls.
> I'd imagine the engineering costs are pretty high, though ... getting
> all of the pathways right so the part fills the mold properly, and cures
> properly.
More to the point, apparently IM machines are rated on the amount of
pressure they can clamp the mould down with - measured in tonnes. (!)
Apparently the cheap ones manage 3-4 tonnes, and the best reach 6,000
tonnes or more. O_O
> My el-cheapo Casio has a metal chassis. Ask me how I know ... I had to
> pull it apart to fix the MIDI out port ... stupid thing came un-soldiered.
You as well?
(Actually, you should be glad it even *has* a MIDI port in the first
place! Most cheap keyboards don't.)
We had to take my old ghettoblaster apart after the line in became
loose. After we soldered it back down and reassembled it, we found one
small metal part left over. We still don't know what that was!
Ah, that was a *quality* piece of equipment though. The box boasts 200W
of power, but the actual speakers inside had figures of fractional Watts
crudely printed on them. (2x speakers at 0.5W, 2x woofers at 0.25W.) And
the manual described the line-in sockets as having "> 14% THD". :-D
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Mmm, tasty...
http://en.wikipedia.org/wiki/Injection_molding
http://en.wikipedia.org/wiki/Electrical_discharge_machining
http://en.wikipedia.org/wiki/Electro_chemical_machining
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Invisible wrote:
>
> Jig system?
>
> What are you trying to cut? Kryptonite??
>
Jigging -- A means of holding something together while you work on it.
Tack on another 10K for the rolling press... btw. (You have to press the
plates into the truss.)
The saws cut ordinary wood, but they're robotic. Lots of engineering and
programming time goes into them.
>
> More to the point, apparently IM machines are rated on the amount of
> pressure they can clamp the mould down with - measured in tonnes. (!)
> Apparently the cheap ones manage 3-4 tonnes, and the best reach 6,000
> tonnes or more. O_O
>
If you can find it in your country, check out the show "How Its Made"
Here it appears on the Discovery Science network. They detail many
industrial processes. It blows my mind how these huge presses seem to
stamp out such things as screwdrivers with nearly no effort.
The U.S. mint apparently uses 84 tons of pressure to press a coin. All
applied in an instant! Hundreds of times a minute.
>
> You as well?
>
> (Actually, you should be glad it even *has* a MIDI port in the first
> place! Most cheap keyboards don't.)
>
Well, I had aspirations of creating music on the computer a long time
ago, and decided a MIDI keyboard was the appropriate input device. That
didn't work out... :)
--
~Mike
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"Invisible" <voi### [at] dev null> wrote in message
news:494655da$1@news.povray.org...
> It kinda makes you wonder how anything ever gets made in the first place!
Yes, you need a lathe to make a lathe.
~Steve~
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Invisible wrote:
> Mmm, tasty...
>
> http://en.wikipedia.org/wiki/Injection_molding
> http://en.wikipedia.org/wiki/Electrical_discharge_machining
> http://en.wikipedia.org/wiki/Electro_chemical_machining
Also neat:
http://en.wikipedia.org/wiki/Ultrasonic_welding
--
~Mike
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>> It kinda makes you wonder how anything ever gets made in the first place!
>
> Yes, you need a lathe to make a lathe.
Hee... My uncle has a 2 tonne lathe.
It's big.
But then, this same uncle also has a 3-foot spannar. And a laser cutting
tool.
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