Pro/Forums - View Single Post - Polycarbonate Tops... a scientiffic analysis!

WinFlex · 03-12-2003, 11:43 AM

The goal of this thread is to gather evidence regarding the claim that clear plastic tops (whatever shapes and materials they come in) are prone to cracking. This all started in the form of several PM's being sent back and forth between Billa and I. I will transcribe them here.
Recognizing and understanding the factors involved in the failiure of waterblock tops will help others avoid following in the footsteps of those poor few who have actually experienced a leak inside the computer.
If you have experienced a leak, please report it here along with details on the type of top you used... thank you, I hope this becomes an interesting discussion.
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WinFlex wrote on 03-12-2003 08:17 AM:
uh. regarding that polypropylene thing, that was a typo... polycarb is what i was actually talking about ... sorry... i edited it as soon as i realized the mixup
it is true, however. many people use plexiglass which easily shatters or cracks. lexan is much, much more durable for it is not an acrylic resin... they even use 1/2 inch lexan for bullet proof windows in banks, etc
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unregistered wrote on 03-12-2003 09:33 AM:
no problem, I assumed the error - just prodding for accuracy
one needs to focus on the specific properties of interest
which for wb tops with threaded connections is going to be the crack propagation
both matls are crappy, it is terribly difficult to 'cut' threads w/o microcracks
Regards, Bill
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WinFlex wrote on 03-12-2003 09:19 AM:
very true. when I was tapping the threads for my latest waterblock (you may have seen it here or over at ocforums), I had to twist the ntp tap in all the way in order to get my polypropylene (now this time I meant to say this) fittings to bottom out nicely. However, I did not notice any kind of cracks forming... how would these microcracks become noticable? I tested my block for 24 hours and I observed absolutely no liquid leaking out... regarding crack propagation in polycarbonates (most plastics, actually), I think it takes more than a steady applied force to cause eventual failiure... the steady "push" from the barbs that are screwed in the lexan (polycarb) top certainly won't be enough to cause any cracks that were initiated druing tapping / fitting insertion to propagate...
what do you think?
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post as a thread
black light and magnification (plus refractive oil ?)
google on crack tip energy
tightening the threaded connection imposes a radial stress
short term is NOT long term + moisture + heat
you have it all wrong, as do most mfgrs
Bill
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I am aware that ultraviolet electromagnetic radiation (aka blacklight) has deprimental effects on both structural and optical properties of polycarbonates. I am unclear on what you mean by refractive oil and magnification...
Certainly something worth looking into... an interesting topic. Do you have any case studies at hand that would describe catastrophic failiure of a 0.5 inch or thicker lexan top? If so, please describe them or list some names of the people it happened to so I can contact them.
As for trasforming this PM conversation into a thread, I will start one right now... We have certainly hit a topic here that should be investigated on a scietiffic level, not a "you have it all wrong" level. Claims should be backed with solid evidence in the form of case studies, examples, calculations, or other experimental results.
By the way, english is my second language, so please explain what the acronym "mfgrs" stands for.
I appreciate your time, let's make this a good, interesting thread to read...
- Felix
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03-12-2003, 11:43 AM	#1
WinFlex Cooling Neophyte Join Date: Feb 2003 Location: Boston, MA, USA Posts: 51	Polycarbonate Tops... a scientiffic analysis! The goal of this thread is to gather evidence regarding the claim that clear plastic tops (whatever shapes and materials they come in) are prone to cracking. This all started in the form of several PM's being sent back and forth between Billa and I. I will transcribe them here. Recognizing and understanding the factors involved in the failiure of waterblock tops will help others avoid following in the footsteps of those poor few who have actually experienced a leak inside the computer. If you have experienced a leak, please report it here along with details on the type of top you used... thank you, I hope this becomes an interesting discussion. --- WinFlex wrote on 03-12-2003 08:17 AM: uh. regarding that polypropylene thing, that was a typo... polycarb is what i was actually talking about ... sorry... i edited it as soon as i realized the mixup it is true, however. many people use plexiglass which easily shatters or cracks. lexan is much, much more durable for it is not an acrylic resin... they even use 1/2 inch lexan for bullet proof windows in banks, etc --- unregistered wrote on 03-12-2003 09:33 AM: no problem, I assumed the error - just prodding for accuracy one needs to focus on the specific properties of interest which for wb tops with threaded connections is going to be the crack propagation both matls are crappy, it is terribly difficult to 'cut' threads w/o microcracks Regards, Bill --- WinFlex wrote on 03-12-2003 09:19 AM: very true. when I was tapping the threads for my latest waterblock (you may have seen it here or over at ocforums), I had to twist the ntp tap in all the way in order to get my polypropylene (now this time I meant to say this) fittings to bottom out nicely. However, I did not notice any kind of cracks forming... how would these microcracks become noticable? I tested my block for 24 hours and I observed absolutely no liquid leaking out... regarding crack propagation in polycarbonates (most plastics, actually), I think it takes more than a steady applied force to cause eventual failiure... the steady "push" from the barbs that are screwed in the lexan (polycarb) top certainly won't be enough to cause any cracks that were initiated druing tapping / fitting insertion to propagate... what do you think? --- post as a thread black light and magnification (plus refractive oil ?) google on crack tip energy tightening the threaded connection imposes a radial stress short term is NOT long term + moisture + heat you have it all wrong, as do most mfgrs Bill --- I am aware that ultraviolet electromagnetic radiation (aka blacklight) has deprimental effects on both structural and optical properties of polycarbonates. I am unclear on what you mean by refractive oil and magnification... Certainly something worth looking into... an interesting topic. Do you have any case studies at hand that would describe catastrophic failiure of a 0.5 inch or thicker lexan top? If so, please describe them or list some names of the people it happened to so I can contact them. As for trasforming this PM conversation into a thread, I will start one right now... We have certainly hit a topic here that should be investigated on a scietiffic level, not a "you have it all wrong" level. Claims should be backed with solid evidence in the form of case studies, examples, calculations, or other experimental results. By the way, english is my second language, so please explain what the acronym "mfgrs" stands for. I appreciate your time, let's make this a good, interesting thread to read... - Felix ---