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Plastic types and their usage in the manufacture of model kits...question

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  • Member since
    January 2006
  • From: NW Washington
Plastic types and their usage in the manufacture of model kits...question
Posted by dirkpitt77 on Tuesday, December 23, 2008 10:00 PM

     So, 

 

         I have a project in mind for which I'll need to hire a plastics company to thermoform a one-off for me.  Basically it's a classic UFO hull.  I've been unable to find both material and a method to do this myself.

       So anyway, my question is, we all know the plastic that models are made out of is known as styrene.  Is this the same as polystyrene?  Is the use of polystyrene an industry standard in model kit manufacturing?  If not, does the material used vary with the manufacturer according to their whim?  Does region, as in North America, Europe, Asia, etc, dictate what material is used?  Is there a way to find out the differences in plastic used from manufacturer to manufacturer (i.e. Revell, Hasegawa, Trumpeter, Dragon, Italeri, etc.)

          All the above questions notwithstanding, when I go to an industrial/commercial plastics supplier who does thermoforming, what plastic should I ask for in order to get the closest analogue to a styrene model kit?  Is all styrene the same? 

       What about any writeups or other posts online about this subject?

 

    All help appreciated,

 

    Chris

    "Some say the alien didn't die in the crash.  It survived and drank whiskey and played poker with the locals 'til the Texas Rangers caught wind of it and shot it dead."

  • Member since
    August 2005
  • From: Sydney, Australia
Posted by Phil_H on Wednesday, December 24, 2008 12:48 AM

Yep, generally speaking, the majority of commercial injection-moulded model kits are made of polystyrene - "styrene" is the same material and is simply a contraction of "polystyrene".

There were a number of kits in recent years (the infamous Trumpeter T-54/55 kits) which reportedly used an odd (for model kits anyway) ABS-like plastic which resisted "normal" model cement.

I think the process you're describing is similar to that used in vacforming, in which a sheet of polystyrene is heated until soft, and placed over a "form", after which the air between the softened sheet and the form is removed, drawing the softened material down onto the form to mould the piece.  

If you have built a few kits from different manufacturers, you may have noticed that the material does vary quite a bit. Tamiya's and Hasegawa's is quite hard and reasonably strong. Dragon's is hard but can be brittle. Academy's is rather soft and can be carved like cheese. Some are densely pigmented, others can be semi-translucent. Though they are all, at the base level, polystyrene, each manufacturer has their own blend. Some add more "filler" material so as to use less "raw" styrene" for example, and/or less pigment to reduce costs.

 

  • Member since
    June 2008
  • From: Iowa
Posted by Hans von Hammer on Wednesday, December 24, 2008 10:12 AM

The plastic I use in vac-forming is either acetate or ABS, depending on whether it's clear or not.  The poystyrene sheets that came with my Vac-u-form are long gone, lol...    For styrene sheets and strips, go with Evergreen.  Plastruct is ABS and molded into structural shapes (angle iron, flats, channel, I-beams, etc) and doesn't seem to like the cement I use, Testor's Liquid, but I use it anyway, or CA...  I'd imagine that Tenax will work on it nicely though, plus Plastruct has it's own brand of cement for it's stuff, though I've never used it... 

At the plastics place, you should have any issues with what they use though, even if it's Plexiglass/PVC or anything not polystyrene, except polyvinyl That stuff hates paint and most glues...   It's going to boil down to the glues you need to use to join the materials, rather than the material itself... 

Also, a good source for polystyrene that's dirt-cheap is the plastic "garage sale/For Sale/Beware of Dog"-type signs in the hardware store... They can be a little thin, but there's no reason you can't laminate them for thicker stuff...

There's several places you can get plans for building your own vacuforming rig as well... It may seem daunting, but it's really not, and once you start vacuforming your own stuff, you'll look back in amazement and wonder how you ever lived without it... Here's a couple:

http://www.hyperscale.com/2007/reviews/tools/vacuboxreviewfm_1.htm

http://www.starshipmodeler.com/tech/jw_vac.htm

http://www.robots.ox.ac.uk/~wmayol/resources/nacipobre/index.html

I may have strayed a bit from you topic, but I thought you might want to look these over anyway...

 

 

  • Member since
    January 2006
  • From: NW Washington
Posted by dirkpitt77 on Wednesday, December 24, 2008 5:04 PM

    Cool, good info.  Thanks guys!

 

      Hans, thanks for the links.  This spring we hope to be doing a bunch of home improvement projects to the house, one of which will be an attached tool shed/project area.  That vacuform setup would be a nice addition to it.  Looks promising and worth a try!

 

    Chris

    "Some say the alien didn't die in the crash.  It survived and drank whiskey and played poker with the locals 'til the Texas Rangers caught wind of it and shot it dead."

  • Member since
    September 2012
Posted by namrednef on Thursday, December 25, 2008 9:58 AM

 

HvH.....If you didn't stray a bit we'd never learn!Laugh [(-D]

I am going to stray a bit to say that I've found that those few ounces of plastic that make up a Toyota wheel hubcap cost over $100 to replace!

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