the importance of thermostats

Brent > wrote in
:

> On 2013-09-20, T0m $herman >
> wrote:
>> On 9/20/2013 12:52 PM, Brent wrote:
>>> On 2013-09-20, jim beam > wrote:
>>>> On 09/20/2013 09:15 AM, Brent wrote:
>>>>> [...] However in real life "die casting" is a process for metal.
>>>
>> Or playing craps at the casino.
>>
>>>>> It's not particularly
>>>>> specialized, much less specialized than doing mohr's circles after
>>>>> graduation.
>>>
>>>> AS AN ENGINEER. engineer's know about mohr's circle. or they
>>>> should if they graduated from anything better than r.m.u.
>>>
>>> Vague rememberance for most anyone still working. Nobody is going to
>>> ask about Mohr's circle on a job interview to hire an engineer. How
>>> to deal with knit lines is far more probable.
>>>
>> You have obviously never looked at the results of an triaxial shear
>> test then. I have not done so at work for over 2 hours.
>
> In the context of mechanical engineering, a vague rememberence for
> most anyone still working. Better?
>
>
>
>
>
>



After running out of popcorn while reading this highly-entertaining
squabble-thread, I looked up Mohr's circle. Wiki has this:
https://en.wikipedia.org/wiki/Mohr%27s_circle

I tried to read that page, but it went so far over my head that I swear I
saw shavings fall off the moon as the page swooshed by.

It's weird how a thread that began with automobile thermostats has morphed
into a ****ing-match about the manufacturing of molded components, and
about who knew what about which, and when he knew it, and whether he knew
anything at all in the first place.

If I didn't know better, I'd swear you guys are actually having /fun/
sniping at each other.

So. Explain to the ignoramus: What /are/ "knit lines"? and how can they
cause catastrophic failure of my injection-molded components?

--
Tegger

On 2013-09-21, Tegger > wrote:
> Brent > wrote in
> :
>
>> On 2013-09-20, T0m $herman >
>> wrote:
>>> On 9/20/2013 12:52 PM, Brent wrote:
>>>> On 2013-09-20, jim beam > wrote:
>>>>> On 09/20/2013 09:15 AM, Brent wrote:
>>>>>> [...] However in real life "die casting" is a process for metal.
>>>>
>>> Or playing craps at the casino.
>>>
>>>>>> It's not particularly
>>>>>> specialized, much less specialized than doing mohr's circles after
>>>>>> graduation.
>>>>
>>>>> AS AN ENGINEER. engineer's know about mohr's circle. or they
>>>>> should if they graduated from anything better than r.m.u.
>>>>
>>>> Vague rememberance for most anyone still working. Nobody is going to
>>>> ask about Mohr's circle on a job interview to hire an engineer. How
>>>> to deal with knit lines is far more probable.
>>>>
>>> You have obviously never looked at the results of an triaxial shear
>>> test then. I have not done so at work for over 2 hours.
>>
>> In the context of mechanical engineering, a vague rememberence for
>> most anyone still working. Better?
>>
>>
>>
>>
>>
>>
>
>
>
> After running out of popcorn while reading this highly-entertaining
> squabble-thread, I looked up Mohr's circle. Wiki has this:
> https://en.wikipedia.org/wiki/Mohr%27s_circle
>
> I tried to read that page, but it went so far over my head that I swear I
> saw shavings fall off the moon as the page swooshed by.
>
> It's weird how a thread that began with automobile thermostats has morphed
> into a ****ing-match about the manufacturing of molded components, and
> about who knew what about which, and when he knew it, and whether he knew
> anything at all in the first place.
>
> If I didn't know better, I'd swear you guys are actually having /fun/
> sniping at each other.

I needed something to entertain me while running FEAs that take two
hours for each run .

> So. Explain to the ignoramus: What /are/ "knit lines"? and how can they
> cause catastrophic failure of my injection-molded components?

Knit lines or weld lines may form where two (or more) flows of material
meet in the mold. Usually near a feature that causes the flow to split
and move around the steel of the mold. It can also occur when a part has
more than one gate (where material is injected). At this location the
material isn't as strong. If it is a critical area stress wise cracks
will develop along the knit line.

Here's a simulation of molding that calculates warp, weld lines, etc.
http://www.youtube.com/watch?v=KQWsDNmVD0E

On 09/20/2013 11:02 AM, Brent wrote:
> On 2013-09-20, jim beam > wrote:
>
>>> Nor was your answer about
>>> crystal formation in cooling metals in any remote way relevant. You
>>> can't even come up with a bull**** way to make it relevant. All you do
>>> is bluster and insult. YOU FAILED.
>>
>> um, crystallization or solidification are not unique to metals retard.
>> either you're just unspeakably stoooopid or you're bull****ting.
>
> Perhaps you noticed I never stated that either was unique to metals.

so why did you say "your answer about crystal formation in cooling
metals" then??? ****ing bull****ting retard.


> However, "complex three-dimensional anisotropic solidification
> contraction" Is a hamfisted showy way of expressing the different
> crystal structures that occur on the outside of metal part compared to
> the interior as the material cools and contracts.

bull****. "solidification" != "crystallization". solidification
/includes/ crystallization, but amorphous solids don't crystallize as
they set. ****ing idiot that clearly doesn't know their own supposed
business.


> It's what I would
> expect of someone who wants to show off what they learned from a second
> semester material science text.

uh, so how many years have you been pressing the "go" button on that
injection molding machine? i know you guys don't need to know much
about what goes on, but if you want to masquerade as a "DEGREED
ENGINEER", you should at least /attempt/ to pick up some info along the way.


>
>>> "modeling complex three-dimensional anisotropic solidification
>>> contraction"
>>>
>>> LOL!
>>>
>>> Oh and it was "injection molded plastic part", much like "die casting"
>>> you can't understand terms as they are used in the real world. That's
>>> why you can't answer real world questions.
>>
>> you /still/ don't know what "plastic" means??? look it up!!!
>
> Word isolation is a big thing with you. Perhaps that's why you get
> things so wrong.

as opposed to the leg-humping retard that blusters and bull****s because
it sustains attention from his homoerotic fantasy...


--
fact check required

On 09/20/2013 10:52 AM, Brent wrote:
> On 2013-09-20, jim beam > wrote:
>> On 09/20/2013 09:15 AM, Brent wrote:
>>> On 2013-09-20, jim beam > wrote:
>>>> On 09/20/2013 07:31 AM, Brent wrote:
>>>>> On 2013-09-20, jim beam > wrote:
>>>>>> On 09/19/2013 09:09 PM, Brent wrote:
>>>>>>> On 2013-09-20, jim beam > wrote:
>>>>>>>> On 09/19/2013 08:39 PM, Brent wrote:
>>>>>>>>> On 2013-09-20, jim beam > wrote:
>>>>>>>>>> On 09/19/2013 07:43 PM, Brent wrote:
>>>>>>>>>>> On 2013-09-20, jim beam > wrote:
>>>>>>>>>>>> On 09/19/2013 05:48 PM, Brent wrote:
>>>>>>>>>
>>>>>>>>>>>> castings are for resins, i.e. self-linkers, not thermoplastics.
>>>>>>>>>>>
>>>>>>>>>>> "die casting" is a process for metals it does not mean "resin casting".
>>>>>>>>>>
>>>>>>>>>> oh brother. resins are cast all the time.
>>>>>>>>>>
>>>>>>>>>> example:
>>>>>>>>>> <http://www.eplastics.com/Plastic/Resin/Casting-Resin-32-Oz-Non-Returnable>
>>>>>>>>>>
>>>>>>>>>> idiot retard.
>>>>>>>>>
>>>>>>>>> LOL. look at the moron divert the subject to cover his ignorance.
>>>>>>>>> https://en.wikipedia.org/wiki/Die_casting
>>>>>>>>> "Die casting is a metal casting process that is characterized by forcing
>>>>>>>>> molten metal under high pressure into a mould cavity."
>>>>>>>>>
>>>>>>>>> Resin casting != Die casting.
>>>>>>>>
>>>>>>>> er, "die", look it up. idiot. and "die casting" means many things - to
>>>>>>>> people that actually know anything about it.
>>>>>>>
>>>>>>> You're so ****ing predictable and ignorant. You have no clue how to
>>>>>>> communicate technically with anyone besides yourself. Nobody, and I mean
>>>>>>> nobody means resin casting when they say die casting. Except you when
>>>>>>> you try to save face after the fact.
>>>>>>
>>>>>> you simply don't understand because you're WAY out of your depth. but
>>>>>> you don't understand even that so you'll just keep on blustering and leg
>>>>>> humping. and because you're a retard.
>>>>>
>>>>> *yawn*
>>>>>
>>>>> Nobody in the real world calls resin casting die casting. Nobody.
>>>>
>>>> you mean, retards that don't know what a "die" is get confused. like
>>>> you. either that or you're being deliberately dishonest.
>>>
>>> *Yawn* your face saving is getting tiresome. Go start calling die cast
>>> houses asking for resin casting. See what happens.
>>
>> no, retard, /you/ go to a few resin casting houses and find out what
>> they call their "forms". clue: it begins with "d".
>
> LOL. You really don't have any real world experience what so ever. Yes,
> tools are called dies. They are called dies in a wide variety of
> processes. However in real life "die casting" is a process for metal.

there are many different processes for casting metal. only a few are
called die casting. besides, "die cast" is layman's language for
something they don't understand. but you won't know that because you
don't work in the field and don't know anything about it.


>
> Do a google search for "die casting" You won't get resin casting places.

yeah, it'll get me a bunch of non-specific stuff written by people like
you who are imprecise in their english.


>
> Perhaps you could ask NADCA:
> "Die casting is a versatile process for producing engineered metal parts
> by forcing molten metal under high pressure into reusable steel molds.

no, that's pressure casting. or rheocasting. or thixoforming. "die
casting" is anything with a mold using a liquid metal [which is a very
important distinction that you'll never understand] and gravity.


> These molds, called dies, can be designed to produce complex shapes with
> a high degree of accuracy and repeatability. Parts can be sharply
> defined, with smooth or textured surfaces, and are suitable for a wide
> variety of attractive and serviceable finishes."

yeah, "attractive". engineers use that highly scientific and precise
language all the time.


>
>
>>>>>>>> bluster all you want, idiot. fact is, you don't know what you're
>>>>>>>> talking about. all you're doing is attacking the gap between what i
>>>>>>>> told you, and what you don't know. and you're still too ****ing dumb to
>>>>>>>> understand that even after being told.
>>>>>>>
>>>>>>> You babbled in your hack language by stringing together words that
>>>>>>> really aren't used together about what happens when cast metals cool and
>>>>>>> shrink. That's not knit lines. You failed. Failed. Failed. You Failed.
>>>>>>
>>>>>> you're delusional and dishonest.
>>>>>>
>>>>>>
>>>>>> * or is it "for"?
>>>>>
>>>>> "modeling complex three-dimensional anisotropic solidification
>>>>> contraction "
>>>>>
>>>>> LOL!
>>>>
>>>> bluster won't save you brent. fact is, you're a retard that doesn't
>>>> know what they hell they're talking about. you show up on this thread
>>>> blathering about a book you've clearly never read [and can't figure out
>>>> how to authenticate], all while contributing absolutely nothing to the
>>>> topic at hand. as usual. and from there, you go down hill.
>>>
>>> blah blah blah blah still no explaination.
>>
>> ????????? explain what???? i'm simply stating the facts as you insist
>> on presenting them!
>
> "modeling complex three-dimensional anisotropic solidification
> contraction" as it relates to knit lines in injection molded plastic
> parts.
>
>>> Oh and I'd like you to prove I "bleat" anything about "engineering
>>> credentials". I haven't told you a damn thing about my "credentials"
>
>> you've called yourself, and i quote, a "degreed engineer". on multiple
>> occasions. if that's not trying to assert credentials, then either you
>> don't understand english, or you're now a coward backing away from their
>> unsupportable bull****.
>
> No I stated you have a problem with anyone who is a "degreed engineer"
> or indentifies themselves as such. Which you do.

no, i have a problem with clueless idiots. that would be people like
you blathering complete nonsense, and then when caught with their pants
down [sorry brent, that would be you in both ways], trying to bluster
and bull**** about being an "engineer" as if it compensates. fact is,
if they can't say anything that stands on its own merits, then they have
no business trying to play the "engineer" card.


> All you have to do is
> find something in the google groups archive posted in the last 5
> years to support your claim. Now even older than a year doesn't amount
> to "bleating", but I'll give you five.

you don't need to look past this self-same thread!!!! idiot nonsense.


>
>>>> as for your supposed engineering credentials, you're simply not
>>>> evidencing any. if you didn't claim to have them, it wouldn't matter.
>>>> but if you do claim to have them, then fail to produce any evidence,
>>>> it's a big deal. particularly when you can't even attend to simple
>>>> technical language like "crystallization" and bull**** about common
>>>> molding polymers [in your supposed field of expertise] not being
>>>> semi-crystalline.
>
>>> Blah blah blah.... who said it was my area of expertise? Not me. I said
>>> it was a simple question that someone with real
>>> engineering/manufacturing experience could answer.
>
>> nobody who isn't in the field would bother to know it - so either you're
>> lying about this or you're just a sad sack who doesn't know anything
>> about what they do. [which we already know by your own admission btw]
>
> It's general manufacturing knowledge. It's real world.

it's not relevant to anyone in the mechanics, electronics, hydraulics,
aerospace, marine, [etc. etc.]. fact is, you're bull****ting brent.
about one tiny little element of one tiny little field of a very
specific operation. nobody outside the field would bother to know it.


> Not something out
> of text book people who do haven't touched for 20 years. Certainly less
> specialized than swapping Honda cams from engine to engine, which you
> considered a valid question. It is covered in design and manufacturing
> courses taken at roughly the same time as heat and mass transfer in the
> same degree programs. Another reason I knew you couldn't answer it.

wouldn't answer down at your level you mean.


>
>>> even if they never
>>> finished HS. The fact of the matter is you failed to answer a simple
>>> real world engineering question correctly.
>
>> no, i answered it in more detail than you deserved. but you don't
>> understand because you didn't know what you were asking.
>
> You mentioned something entirely different.
> "three-dimensional anisotropic solidification contraction"

oh dear. i guess i need to beat some sense into your tiny cranial cavity.

so, when you mold your "semi-chrystalline" polymer, you heat it. let's
call that liquid at T1. when you inject, the mold, by definition, has
to be at a lower temperature. let's call that T2, and that is below Ts,
the solidification range. any liquid flowing quickly drops temperature
according to the temperature delta T1 - T2, and it's solidification rate
is controlled by that delta, and any latent heat of solidification,
thermal conductivity of the polymer, etc.

so, if two fully liquid flow fronts intersect, there is no "knit/weld"
because the liquids are miscible. you only have issues if you're having
two [still liquid but rapidly cooling] fronts meet at temperatures below
Ts. so, the whole point of molding is to know your mechanical
application, then devise an injection scheme that is appropriate to that
application - because the solidification, in three dimensions, and
resultant anisotropy, can be modeled. it's not for idiots. and it's
expensive. who gets it depends on how much the customer wants to pay.

but you knew all that didn't you brent? oh, wait, you didn't because
you'd have said so already rather than just ****ing bleat about a
problem that you apparently don't know how to address.


>
>>> It's not particularly
>>> specialized, much less specialized than doing mohr's circles after
>>> graduation.
>
>> AS AN ENGINEER. engineer's know about mohr's circle. or they should if
>> they graduated from anything better than r.m.u.
>
> Vague rememberance for most anyone still working.

bull****. you don't even "remember" it with the vast power and
information of the net at your fingertips.


> Nobody is going to ask
> about Mohr's circle on a job interview to hire an engineer.

???? they sure are if they're going to be a real engineer that's
testing anything as opposed to interviewing a machine operator!!!


> How to deal
> with knit lines is far more probable.

for a low-end injection machine operator...


>
>>> Of course specialized never stopped you when you
>>> considered a backyard Honda engine modification question general
>>> engineering.
>
>>> Your words, reek of someone who couldn't make it. You have to show those
>>> who did how much better you are because you think you've mastered stuff
>>> engineers working in the real world haven't had to touch for 20 years.
>>> Then you distort and mix up the terms such that nobody else will
>>> understand you and play gotchas. You're a poster child of the person who
>>> for whatever reason just didn't make it and is angry about it and acting
>>> out.
>>>
>>> I chose that particular question because it was exceedingly simple and
>>> easy to answer by anyone who has worked in real world engineering
>
>> no, retard, it's factory floor technician level. [not that there's
>> anything wrong with technicians, but they shouldn't claim to be "degreed
>> engineers" when they're clearly not.]
>
> Factory floor technician level... you're showing your ignorance again.
> Knowledge of knit lines indeed does go down to the factory floor but it
> goes all the way up to university research. This is what makes it a good
> question.

for a machine operator...


>
> There's far more behind knit lines, and it's not "complex
> three-dimensional anisotropic solidification contraction"
>
> Call up some papers on weld lines. Here's one for you:
> http://kazmer.uml.edu/Staff/Archive/...d_Strength.pdf

whoopee.


>
>>> where parts are manufactured but does not typically appear in first or
>>> second year math based coursework. It doesn't require any education to
>>> understand, just real world experience. It's not in your first year
>>> material science book from which you cobbled together:
>>> "modeling complex three-dimensional anisotropic solidification
>>> contraction"
>
>> hey, i'm sorry you're having such a hard time with technical language
>> brent. perhaps you should learn english? then you can learn technical
>> english.
>
> Let me know when you start writing it. At least the kind people in the
> real world use.

funny. how about i let you know when i use technical english as well?


>
>
>>> You are such an easy mark in that regard.
>>>
>>> Oh by the way, it could appear in third or fourth year general
>>> manufacturing texts...
>>
>> "fourth year manufacturing texts"??? would these be the ones that
>> somehow fail to convey the difference between amorphous and
>> semi-crystalline? or is it semi-chrystalline - you've got me confused.
>
> Usual diversion....

no, you were bull****ting. because you're ignorant and don't know what
you're talking about. and i'm calling you on it.


>
>>>> bottom line, you /never/ contribute anything of relevance or value - all
>>>> you do is **** and moan. and **** up. but that's because you're a
>>>> retard and are too anosognosic to even know it.
>>>
>>> You're projecting again Beam.
>>
>> sorry my homo-antagonistic wannabe - i'm merely telling the truth.
>
> Keep on projecting.

how's that one-handed typing? can you even /do/ that if you're anosognosic?


--
fact check required

On 2013-09-21, jim beam > wrote:
> On 09/20/2013 11:02 AM, Brent wrote:
>> On 2013-09-20, jim beam > wrote:
>>
>>>> Nor was your answer about
>>>> crystal formation in cooling metals in any remote way relevant. You
>>>> can't even come up with a bull**** way to make it relevant. All you do
>>>> is bluster and insult. YOU FAILED.
>>>
>>> um, crystallization or solidification are not unique to metals retard.
>>> either you're just unspeakably stoooopid or you're bull****ting.
>>
>> Perhaps you noticed I never stated that either was unique to metals.
>
> so why did you say "your answer about crystal formation in cooling
> metals" then??? ****ing bull****ting retard.

>> However, "complex three-dimensional anisotropic solidification
>> contraction" Is a hamfisted showy way of expressing the different
>> crystal structures that occur on the outside of metal part compared to
>> the interior as the material cools and contracts.

> bull****. "solidification" != "crystallization". solidification
> /includes/ crystallization, but amorphous solids don't crystallize as
> they set. ****ing idiot that clearly doesn't know their own supposed
> business.

Look at the idiot squirm. Except you didn't write amporhous. You wrote
anisotropic. Squirm squirm squirmy. What you did is jam a bunch of words
together to sound like you knew something. Now you keep pretending each
word stands separately instead of together. Yes, amorphous materials
shrink too, and they don't crystalize in the process, but you modified
solidification with anisotropic. It's fun to watch you squirm.


>> It's what I would
>> expect of someone who wants to show off what they learned from a second
>> semester material science text.

> uh, so how many years have you been pressing the "go" button on that
> injection molding machine? i know you guys don't need to know much
> about what goes on, but if you want to masquerade as a "DEGREED
> ENGINEER", you should at least /attempt/ to pick up some info along the way.

"modeling complex three-dimensional anisotropic solidification"

LOL.

>>>> "modeling complex three-dimensional anisotropic solidification
>>>> contraction"
>>>>
>>>> LOL!
>>>>
>>>> Oh and it was "injection molded plastic part", much like "die casting"
>>>> you can't understand terms as they are used in the real world. That's
>>>> why you can't answer real world questions.
>>>
>>> you /still/ don't know what "plastic" means??? look it up!!!
>>
>> Word isolation is a big thing with you. Perhaps that's why you get
>> things so wrong.
>
> as opposed to the leg-humping retard that blusters and bull****s because
> it sustains attention from his homoerotic fantasy..


HAHAHAAHAHAHAHAHAHAHAHAHAHHAHA!

On 09/21/2013 08:36 AM, Brent wrote:
> On 2013-09-21, jim beam > wrote:
>> On 09/20/2013 11:02 AM, Brent wrote:
>>> On 2013-09-20, jim beam > wrote:
>>>
>>>>> Nor was your answer about
>>>>> crystal formation in cooling metals in any remote way relevant. You
>>>>> can't even come up with a bull**** way to make it relevant. All you do
>>>>> is bluster and insult. YOU FAILED.
>>>>
>>>> um, crystallization or solidification are not unique to metals retard.
>>>> either you're just unspeakably stoooopid or you're bull****ting.
>>>
>>> Perhaps you noticed I never stated that either was unique to metals.
>>
>> so why did you say "your answer about crystal formation in cooling
>> metals" then??? ****ing bull****ting retard.
>
>>> However, "complex three-dimensional anisotropic solidification
>>> contraction" Is a hamfisted showy way of expressing the different
>>> crystal structures that occur on the outside of metal part compared to
>>> the interior as the material cools and contracts.
>
>> bull****. "solidification" != "crystallization". solidification
>> /includes/ crystallization, but amorphous solids don't crystallize as
>> they set. ****ing idiot that clearly doesn't know their own supposed
>> business.
>
> Look at the idiot squirm. Except you didn't write amporhous.

!!!!!!!! you can't even copy correctly - it's A-M-O-R-P-H-O-U-S.


> You wrote
> anisotropic. Squirm squirm squirmy.

uh, they're completely different properties, retard. you can have
anisotropic amorphous solids - toughened glass is an example. and you
can have isotropic crystalline solids. but true isotropy is rare and
amorphousness is not.

but getting back to you, for someone who claims to be a "degreed
engineer" who says they work in materials, you're outstandingly
clueless. have you ever considered going back to your alma mater and
asking for a tuition refund??? they clearly ripped you off if they
didn't teach you anything. and they failed in their duties of
accreditation if they accepted you onto a course you couldn't handle.

either that or you're not what you say you are - which means you're fraud.


> What you did is jam a bunch of words
> together to sound like you knew something. Now you keep pretending each
> word stands separately instead of together. Yes, amorphous materials
> shrink too, and they don't crystalize in the process, but you modified
> solidification with anisotropic. It's fun to watch you squirm.

see above and learn what the words mean. after all, it's what google's
for. [but the fact that you seem consistently incapable of something so
basic speaks volumes. maybe you need to put your other hand back on the
mouse for a moment or two?]


>
>
>>> It's what I would
>>> expect of someone who wants to show off what they learned from a second
>>> semester material science text.
>
>> uh, so how many years have you been pressing the "go" button on that
>> injection molding machine? i know you guys don't need to know much
>> about what goes on, but if you want to masquerade as a "DEGREED
>> ENGINEER", you should at least /attempt/ to pick up some info along the way.
>
> "modeling complex three-dimensional anisotropic solidification"
>
> LOL.

you don't even know what it means.


>
>>>>> "modeling complex three-dimensional anisotropic solidification
>>>>> contraction"
>>>>>
>>>>> LOL!
>>>>>
>>>>> Oh and it was "injection molded plastic part", much like "die casting"
>>>>> you can't understand terms as they are used in the real world. That's
>>>>> why you can't answer real world questions.
>>>>
>>>> you /still/ don't know what "plastic" means??? look it up!!!
>>>
>>> Word isolation is a big thing with you. Perhaps that's why you get
>>> things so wrong.
>>
>> as opposed to the leg-humping retard that blusters and bull****s because
>> it sustains attention from his homoerotic fantasy..
>
>
> HAHAHAAHAHAHAHAHAHAHAHAHAHHAHA!

i'm not laughing at you brent. you shame the technology industry and
pollute the web with your trenchant anosognosic stupidity. frankly,
you're a disgrace.


--
fact check required

Brent > wrote in
:

> On 2013-09-21, Tegger > wrote:

>>
>> If I didn't know better, I'd swear you guys are actually having /fun/
>> sniping at each other.
>
> I needed something to entertain me while running FEAs that take two
> hours for each run



Oho, so you had an ulterior motive.

You picked a good one for entertainment: beam is like a foolish fish that
just can't leave the bait alone. Plus he HAS to have the last word, so you
can keep him going pretty much forever, if you so choose.



>
>> So. Explain to the ignoramus: What /are/ "knit lines"? and how can
>> they cause catastrophic failure of my injection-molded components?
>
> Knit lines or weld lines may form where two (or more) flows of
> material meet in the mold. Usually near a feature that causes the flow
> to split and move around the steel of the mold. It can also occur when
> a part has more than one gate (where material is injected). At this
> location the material isn't as strong. If it is a critical area stress
> wise cracks will develop along the knit line.
>
> Here's a simulation of molding that calculates warp, weld lines, etc.
> http://www.youtube.com/watch?v=KQWsDNmVD0E
>



That was a very interesting video, so thanks for the link. Now I see
exactly what you mean by knit/weld lines. It's obvious that if the lines
were in critical areas they would act as built-in stress-risers. and thus
as potential fail points. The video is also very illustrative in describing
how critical is the placement of the gate(s).

I imagine development of injection-molding must be substantially less
expensive and less time-consuming now than it was before Solidworks and
related software came out. How'd they do the design before? Educated-
guesswork? Tables of some kind?

One thing the narrator didn't address outside of a simple mention was the
air-traps detected by the software. How are those dealt with, just by
drilling some tiny holes in the mold?

Also, I don't quite understand how /increasing/ wall thickness would
/shorten/ cooling times. And I don't understand how shrinkage rates can
decline from ~10% to ~1-2% just with a change in the structure. Or was that
affected by the change in material from PC to PC/ABS?

Note: My hearing is very poor (I wear two hearing aids). The narrator has
an accent, and I am unable to read his lips since he does not appear in the
video, so I may have missed a lot of what he was saying.


--
Tegger

Tegger > wrote in
:

>
> One thing the narrator didn't address outside of a simple mention was
> the air-traps detected by the software. How are those dealt with, just
> by drilling some tiny holes in the mold?




I just noticed that, after the video played, a bunch of suggested "further
reading" links appear to the right of the video screen. My questions are
probably answered in those videos. Will watch some later. Apparently there
are /home/ injection-molding machines!



--
Tegger

On 09/21/2013 02:48 PM, jim beam wrote:

> i'm not laughing at you brent. you shame the technology industry and
> pollute the web with your trenchant anosognosic stupidity. frankly,
> you're a disgrace.

You're the pot calling the good china black, you moron.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On 09/21/2013 05:02 PM, Nate Nagel wrote:
> On 09/21/2013 02:48 PM, jim beam wrote:
>
>> i'm not laughing at you brent. you shame the technology industry and
>> pollute the web with your trenchant anosognosic stupidity. frankly,
>> you're a disgrace.
>
> You're the pot calling the good china black, you moron.
>
> nate
>

apparently you're another one that can't be bothered to look up
"amorphous" and "anisotropic" before sticking your oar in. but you've
never been one to let facts get in the way of your race to the bottom.
which would also of course be why you snipped the facts from the
preceding post - they're just too inconvenient.


--
fact check required