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  • Plastics for rugged handhelds

    Discussion in 'Plastic moulding' started by wizardofid, Nov 4, 2009.

    1. wizardofid

      wizardofid Active Member

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      Hi there

      Does anyone have an idea of what materials have been used in the shells of military or enterprise class rugged handhelds. An example of such products is
      http://www.motorola.com/staticfiles/Bus ... US-EN.html
      http://business.motorola.com/mc9500/index.html

      I know extreme low volume production lends itself to CNC milling aluminium or magnesium. But what about products like this motorola handheld computer? It conforms to all MIL/ IEC/ env specs and is lightweight. Can some light be thrown on the materials used? ABS? Glass Filled ABS?

      VR
       
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    3. MechEngineer

      MechEngineer Member

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    4. Plasticman

      Plasticman New Member

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      I would say that the material used was almost definitely a pc/abs material by one of the major suppliers, check out SABIC Innovative Plastics. Some companies have used bead filled acetal and other material alloys for rugged applications, a lot depends on cost, performance etc.
       
    5. mvalenti

      mvalenti Well-Known Member

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      My experience with night vision goggles for the military we used a glass filled xenoy.
       
    6. wangyangzhong

      wangyangzhong Member

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      We use GE CYCOLOY for Dell rugged lap top covers.
      It's a PC/ABS material,
      Goggle "DELL XFR D630" to read details
       
    7. loughnane

      loughnane New Member

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      PC/ABS is probably the best choice.

      That being said, if you are looking at extremely low volume production you might have difficulty finding a machine shop that has a big enough chunk of PC/ABS on hand.

      I recently worked on a military-grade handheld device for use in intense environments. We cut the prototypes from straight ABS, and it held up really nicely.
       
    8. bcao

      bcao Member

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      We've used Cycoloy / PC-ABS for products that will see environmental abuse.

      Glass-filled nylon is also popular as a strong material to withstand abuse, but not for outdoor (read: wet) applications.
       
    9. wizardofid

      wizardofid Active Member

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      Guys, sorry for delay in getting back to you.

      @mechengineer: thanks for the links. As I suspected we might need to resort to an overmoulding technique, but weight considerations call for a relatively thin wall, and dissipating heat via the plastics are driving us towards a single material moulding, with maybe some corner rubbers.

      @wangyangzhong, thanks for the tip on cycoloy. We used that for smaller thin walled devices in the past. But I should check on how it holds up for this class of device.

      @mvalenti: thanks for the tip. Now, I'm tending towards using Xenoy. I'll have to check on availability in the manufacturer's geography though.

      Having said which, both these materials do not seem like they can hold up to MIL-STD-810E testing (or the equivalent for rugged enterprise class). Did you have to use a backing chassis in Magnesium? Or overmoulded rubber in the corners, etc for protection?

      @loughlane and @bcao: We milled a couple of prototypes out of ABS block, but have only done fitment checks, and some minor IP trials. I'm very wary of urethane casts because they turn out brittle most of the time.
       
    10. mvalenti

      mvalenti Well-Known Member

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      In our case we did not have any overmold, or reinforced chassis. I am looking over the 810 spec. I know some of our tests were cycling through hot and cold, and then expected to work. which the systems did. We also did a drop onto concrete all six sides, from 1 meter, i think that was the height. What aspects of 810 are you concerned with? If I didnt state before, we were using a 30% glass filled xenoy.
       
    11. wizardofid

      wizardofid Active Member

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      An update from my side. Most of the tests that our prototypes have gone through are most unscientific i.e. the buyer isnt exactly clear which standards to adhere to, so we just plod on from experiment to experiment. Also iterations have been in rapid spurts and then we've had to cool off waiting for long response cycles. We made shells many months ago in 1.5~1.8mm thick aluminium (CNC Milled). Very rugged, but it was too heavy for certain applications.

      After reduction in some hardware weight we re-did the design for PC-ABS. However after initial drops from 60~65cm height onto metal and concrete floor, we found that the LCD are close to damage (Still working), and after more repeated drops the 1.8mm shell cracked where the ports and rubber covers had created openings.

      The specifications have been downgraded, but the 60cm drop is important, as is a weight under 1.3kg for a device with a gargantuan battery and display, and a hinge. We're looking at overmoulding TPE as an option. I found a TPE reference here http://www.glstpes.com/products_versollan.php Has anyone used these guys? Are you able to get colours in overmoulding (important in this case)? What thicknesses and shure hardnesses for a rugged handheld are most recommended? I'm guessing that a thickness of less than 1.5mm (0.060in) will not even fill.

      @wangyangzhong thanks for the information on cycoloy used in http://www.dell.com/xfr (Nice work on it). Our device is now a lot less rugged though.
       

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