Sources detail physical design of Apple's upcoming tablet device

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  • addaboxaddabox Posts: 12,667member
    Quote:
    Originally Posted by DaHarder View Post


    [CENTER]Sure...



    Simply because 'unibody' construction techniques are utilized, does not limit said component's manufacture to one substrate or another.



    Example:



    MacBook Pro/Unibody = Aluminum Alloy

    MacBook/Unibody = Plastic Composite[/CENTER]



    That's not what he asked, though: he's asking if composite would give the same benefits as a unibody aluminum chassis, not if it's possible to make a unibody chassis out of materials other than aluminum.
  • carniphagecarniphage Posts: 1,984member
    Quote:
    Originally Posted by DaHarder View Post


    [CENTER]Sure...



    Simply because 'unibody' construction techniques are utilized, does not limit said component's manufacture to one substrate or another.



    Example:



    MacBook Pro/Unibody = Aluminum Alloy

    MacBook/Unibody = Plastic Composite[/CENTER]



    Erm.



    But plastic does not conduct heat as well as metal.

    But plastic does not conduct heat as well as metal. (duplicate post)



    C.
  • daharderdaharder Posts: 1,580member
    Quote:
    Originally Posted by addabox View Post


    That's not what he asked, though: he's asking if composite would give the same benefits as a unibody aluminum chassis, not if it's possible to make a unibody chassis out of materials other than aluminum.



    [CENTER]It depends on the composite utilized...



    Graphite/Carbon Fiber, Kevlar reinforced Plastic, etc.



    They each have their own specific set of attributes.



    Unibody construction is nothing more than a manufacturing technique that supports structural load by using an object's exterior, as opposed to using an internal frame or truss that is then covered with a non-load-bearing skin, and is completely independent of substrate used to create the monocoque/unibody component.





    [/CENTER]
  • daharderdaharder Posts: 1,580member
    Quote:
    Originally Posted by Carniphage View Post


    Erm.



    But plastic does not conduct heat as well as metal.

    But plastic does not conduct heat as well as metal. (duplicate post)



    C.



    [CENTER]Actually...



    That depends on what 'metal' is used.

    [/CENTER]
  • addaboxaddabox Posts: 12,667member
    Quote:
    Originally Posted by DaHarder View Post


    [CENTER]Actually...



    That depends on what 'metal' is used.

    [/CENTER]



    Right. That's why we were talking about aluminum. Composite materials don't conduct heat as well as aluminum, which is why a MacBook Air style uni-body design for a tablet, which in effect makes the entire enclosure a heat sink, would have definite design upsides.
  • daharderdaharder Posts: 1,580member
    Quote:
    Originally Posted by addabox View Post


    Right. That's why we were talking about aluminum. Composite materials don't conduct heat as well as aluminum, which is why a MacBook Air style uni-body design for a tablet, which in effect makes the entire enclosure a heat sink, would have definite design upsides.



    [CENTER]Like I stated previously...



    Each substrate has its attributes.



    Anyway: As it is my birthday today, and the spouse just announced that the 2010 Jeep Wrangler Unlimited parked in front of our house is my birthday present, I'll leave you to continue this 'discussion' without me.



    Have Fun... I Sure Will![/CENTER]
  • mr. memr. me Posts: 3,219member
    Quote:
    Originally Posted by DaHarder View Post


    [CENTER]Actually...



    That depends on what 'metal' is used.

    [/CENTER]



    Apple has only ever used two lightweight metals, aluminum and titanium, to construct its laptops. The thermal conductivities of each choice is as follows



    Metal.................Thermal Conductivity (W/m/K)

    Aluminum .......237

    Titanium..........21.9



    With a coefficient of thermal conductivity more than ten times that of titanium, aluminum is a no-brainer for the construction of Apple laptops. Plastic and composites are not even in the conversation if heat dissipation is a design requirement.
  • solipsismsolipsism Posts: 25,726member
    Quote:
    Originally Posted by Mr. Me View Post


    Apple has only ever used two lightweight metals, aluminum and titanium, to construct its laptops. The thermal conductivities of each choice is as follows



    Metal.................Thermal Conductivity (W/m/K)

    Aluminum .......237

    Titanium..........21.9



    With a coefficient of thermal conductivity more than ten times that of titanium, aluminum is a no-brainer for the construction of Apple laptops. Plastic and composites are not even in the conversation if heat dissipation is a design requirement.



    Doesn?t titanium get more brittle than aluminium when stressed too much? Wasn?t that a problem with some Titanium PowerBooks, or was that simply poor engineering? How is magnesium, like used in the new HP Envys when it comes to thermal conductivity?
  • mr. memr. me Posts: 3,219member
    Quote:
    Originally Posted by solipsism View Post


    Doesn?t titanium get more brittle than aluminium when stressed too much? Wasn?t that a problem with some Titanium PowerBooks, or was that simply poor engineering? How is magnesium, like used in the new HP Envys when it comes to thermal conductivity?



    I think that you missed by point. Aluminum's thermal properties make it a much better choice for a laptop than titanium. Titanium is stronger than aluminum, but its rigidity advantage over aluminum is not overwhelming.



    As for magnesium, its thermal properties have an overwhelming advantage over titanium but are not as good as aluminum. Magnesium is lighter and weaker than aluminum. It has another property that makes it totally inappropriate for a laptop or any device where heat or electricity is an issue.



    Magnesium is combustible. Once lit, it burns blue-white hot. Do you remember the video of the Dell laptop a few years back? When its battery caught fire, it was a sight to see. If that laptop had been constructed of magnesium, then the battery fire would have ignited the case and would have been immeasurably worse.



    With a magnesium laptop, the Christmas bomber would not have needed to hide the explosives in his underwear. With a match and a few scrapings from the case of his computer, he could have created a massive hot fire on the plane.



    Magnesium? Really bad idea.
  • solipsismsolipsism Posts: 25,726member
    Quote:
    Originally Posted by Mr. Me View Post


    I think that you missed by point.



    I got the point. My questions were about other reasons why Titanium is bad, previous issue with titanium Macs and potential other materials that could be used, specifically magnesium as it seems to be growing in popularity a bit.
  • jeffdmjeffdm Posts: 12,936member
    Quote:
    Originally Posted by Carniphage View Post


    Composites? It could be....



    One would need to find one that is stiff and recyclable. The most popularly known composite, carbon fiber / epoxy resin, isn't recyclable and is flimsy. Great tensile strength, very poor on several other measures. The recyclability is an issue, as it needs to be easy to reclaim all components. The current best way to get rid of a CF airframe is to burn it. They aren't easy to use for mass production items, most production CF is still hand laid, aluminum unibody an automated machine does most of the work, the work is even quicker if it's injection molded.



    Quote:
    Originally Posted by Mr. Me View Post


    Apple has only ever used two lightweight metals, aluminum and titanium, to construct its laptops. The thermal conductivities of each choice is as follows



    Metal.................Thermal Conductivity (W/m/K)

    Aluminum .......237

    Titanium..........21.9



    With a coefficient of thermal conductivity more than ten times that of titanium, aluminum is a no-brainer for the construction of Apple laptops. Plastic and composites are not even in the conversation if heat dissipation is a design requirement.



    Also, Titatnium is known to be b!tch to machine, aluminum anything but. A Titanium unibody would have a steep price.



    Quote:
    Originally Posted by Mr. Me View Post


    I think that you missed by point. Aluminum's thermal properties make it a much better choice for a laptop than titanium. Titanium is stronger than aluminum, but its rigidity advantage over aluminum is not overwhelming.



    As for magnesium, its thermal properties have an overwhelming advantage over titanium but are not as good as aluminum. Magnesium is lighter and weaker than aluminum. It has another property that makes it totally inappropriate for a laptop or any device where heat or electricity is an issue.



    Magnesium is combustible. Once lit, it burns blue-white hot. Do you remember the video of the Dell laptop a few years back? When its battery caught fire, it was a sight to see. If that laptop had been constructed of magnesium, then the battery fire would have ignited the case and would have been immeasurably worse.



    With a magnesium laptop, the Christmas bomber would not have needed to hide the explosives in his underwear. With a match and a few scrapings from the case of his computer, he could have created a massive hot fire on the plane.



    Magnesium? Really bad idea.



    Yeah, it seems to me that people are afraid of one-in-a-million risks. For that matter, people don't seem to gauge risks properly.



    I wonder if people should start taking away kid's Hot Wheels toys, zinc is highly flamable too. Nikon cameras use magnesium shells. I think someone could use a Lenovo notebook. Lithium is flammable too, I haven't seen a lot of call to get rid of it as a battery material.
  • flounderflounder Posts: 2,674member
    Quote:
    Originally Posted by Mr. Me View Post


    I think that you missed by point. Aluminum's thermal properties make it a much better choice for a laptop than titanium. Titanium is stronger than aluminum, but its rigidity advantage over aluminum is not overwhelming.



    As for magnesium, its thermal properties have an overwhelming advantage over titanium but are not as good as aluminum. Magnesium is lighter and weaker than aluminum. It has another property that makes it totally inappropriate for a laptop or any device where heat or electricity is an issue.



    Magnesium is combustible. Once lit, it burns blue-white hot. Do you remember the video of the Dell laptop a few years back? When its battery caught fire, it was a sight to see. If that laptop had been constructed of magnesium, then the battery fire would have ignited the case and would have been immeasurably worse.



    With a magnesium laptop, the Christmas bomber would not have needed to hide the explosives in his underwear. With a match and a few scrapings from the case of his computer, he could have created a massive hot fire on the plane.



    Magnesium? Really bad idea.





    I imagine any magnesium laptop is an alloy of some sort not subject to combustion. Any maker of a magnesium based laptop would subject themselves to huge liability otherwise. I assume HP is not THAT stupid. I would imagine the HP laptops referred are probably a magnesium / aluminum alloy.



    No one makes a laptop that could cause a "massive hot fire" with a few scrapings from the case and match.
  • dr millmossdr millmoss Posts: 5,403member
    I remember burning magnesium in the basement when I was a kid. It does indeed burn white-hot, but I also remember that it took a blowtorch to get it started.
  • jeffdmjeffdm Posts: 12,936member
    Quote:
    Originally Posted by Flounder View Post


    I imagine any magnesium laptop is an alloy of some sort not subject to combustion. Any maker of a magnesium based laptop would subject themselves to huge liability otherwise. I assume HP is not THAT stupid. I would imagine the HP laptops referred are probably a magnesium / aluminum alloy.



    No one makes a laptop that could cause a "massive hot fire" with a few scrapings from the case and match.



    Many Thinkpads have had magnesium frames for quite some time, and it looks like many models still use it. I've yet to hear of lawsuits. It's probably safer than using lithium for battery materials.
  • solipsismsolipsism Posts: 25,726member
    I love these discussions!
  • jeffdmjeffdm Posts: 12,936member
    Quote:
    Originally Posted by Dr Millmoss View Post


    I remember burning magnesium in the basement when I was a kid. It does indeed burn white-hot, but I also remember that it took a blowtorch to get it started.



    It needs to be 3100 °C / 5600 °F. Not an easy temperature to achieve. It's probably why the actually as much of a risk as people think it is. A butane torch achieves 1970 °C / 3578 °F. Any oxyacetylene torch gets to the desired temperature, but that's not going to be easy to pass through security.
  • dr millmossdr millmoss Posts: 5,403member
    Quote:
    Originally Posted by JeffDM View Post


    It needs to be 3100 °C / 5600 °F. Not an easy temperature to achieve. It's probably why the actually as much of a risk as people think it is. A butane torch achieves 1970 °C / 3578 °F. Any oxyacetylene torch gets to the desired temperature, but that's not going to be easy to pass through security.



    I don't doubt your numbers, but I'm sure we never had anything hotter than a hardware store butane torch at home, and that worked just fine to ignite magnesium. Does anybody remember slot cars? They were built on magnesium frames. Whenever a car got wrecked beyond repair, we'd torch it on the basement floor. Of course you are correct that you'd never get a torch of any kind through airport security (or so I'd like to think), and even if you could, the most you'd get is a fire, not an explosion. The biggest problem with magnesium as I recall is that it's brittle.
  • flounderflounder Posts: 2,674member
    Quote:
    Originally Posted by JeffDM View Post


    It needs to be 3100 °C / 5600 °F. Not an easy temperature to achieve. It's probably why the actually as much of a risk as people think it is. A butane torch achieves 1970 °C / 3578 °F. Any oxyacetylene torch gets to the desired temperature, but that's not going to be easy to pass through security.



    That is the temp magnesium burns at, but that is not the temp needed to ignite it. For example, they use magnesium in fireworks and flares. For another example, I lit magnesium on fire in high school chemistry class (it was 14 years ago but I still remember!). It comes it little strips, and magnesium naturally forms a thin layer of oxide on its exterior (which is why it doesn't spontaneously combust). You put that little strip of magnesium in the flame of a bunsen burner, and Wheeeee! bright white light!



    I believe it burns quite fast. This is why the magnesium in fireworks / flares aren't causing massive fires left and right. The magnesium is powdered, giving it a large surface area, and is consumed long before it reaches the ground.
  • irelandireland Posts: 16,086member








  • solipsismsolipsism Posts: 25,726member
    Quote:



    That seems overly bulky for Apple. I wonder if they?ll just let 3rd-parties make after-market stands to suit various needs and just keep the tablet design sleek and simple.
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