# Re car shredding machine videos - How do they sort out that mixed up plastic, metal, glass scrap?
**URL:** https://boards.straightdope.com/t/re-car-shredding-machine-videos-how-do-they-sort-out-that-mixed-up-plastic-metal-glass-scrap/716844
**Category:** Factual Questions
**Created:** [April 4, 2015, 11:20pm UTC](https://boards.straightdope.com/t/re-car-shredding-machine-videos-how-do-they-sort-out-that-mixed-up-plastic-metal-glass-scrap/716844 "2015-04-04T23:20:16Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@astro](https://boards.straightdope.com/u/astro)
#### Post date: [April 4, 2015, 11:20pm UTC](https://boards.straightdope.com/t/re-car-shredding-machine-videos-how-do-they-sort-out-that-mixed-up-plastic-metal-glass-scrap/716844/1 "2015-04-04T23:20:16Z")
So [here is a machine](https://www.youtube.com/watch?v=XoeHdjXhxdY#t=134)that shreds up a whole car in smaller pieces.
[Here’s another.](https://www.youtube.com/watch?v=lXfitusZ9qY) it’s almost hypnotic watching them. How hard and powerful those jaws have to be to tear up those engine blocks at the end of the video is boggling.
Re those scrap miles they generate how is all that mixed up shredded material sorted out. Obviously a magnet will get the iron but the aluminum, glass and plastic are still all combined. How do they do it?
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### Author:  [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)
#### Post date: [April 4, 2015, 11:46pm UTC](https://boards.straightdope.com/t/re-car-shredding-machine-videos-how-do-they-sort-out-that-mixed-up-plastic-metal-glass-scrap/716844/2 "2015-04-04T23:46:09Z")
An [eddy current separator](https://en.wikipedia.org/wiki/Eddy_current_separator) will pull the non-ferrous metals out of the pile.
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### Author:  [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)
#### Post date: [April 5, 2015, 12:07am UTC](https://boards.straightdope.com/t/re-car-shredding-machine-videos-how-do-they-sort-out-that-mixed-up-plastic-metal-glass-scrap/716844/3 "2015-04-05T00:07:58Z")
You can also do a density sort by blowing air through the stream of shredded material. Low-density objects will be deflected more.
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### Author:  [@astro](https://boards.straightdope.com/u/astro)
#### Post date: [April 5, 2015, 12:10am UTC](https://boards.straightdope.com/t/re-car-shredding-machine-videos-how-do-they-sort-out-that-mixed-up-plastic-metal-glass-scrap/716844/4 "2015-04-05T00:10:26Z")
> [@Dewey\_Finn](#):
>
> An [eddy current separator](https://en.wikipedia.org/wiki/Eddy_current_separator) will pull the non-ferrous metals out of the pile.
[Fascinating!](https://www.youtube.com/watch?v=vZcZRQRvDS0) Thanks for heads up!
Oddly in wikiing it, [it’s the sparsest wiki I’ve ever seen](http://en.wikipedia.org/wiki/Eddy_current_separator) given there are million of dollars in machines and [entire manufacturing companies](https://www.youtube.com/watch?v=rHemCWkjnB4)devoting to making use of this principle.
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### Author:  [@busterpickle](https://boards.straightdope.com/u/busterpickle)
#### Post date: [April 5, 2015, 1:40am UTC](https://boards.straightdope.com/t/re-car-shredding-machine-videos-how-do-they-sort-out-that-mixed-up-plastic-metal-glass-scrap/716844/5 "2015-04-05T01:40:10Z")
i think the engine blocks have been removed as well as the rims, axles, rotors, transmissions. The only part that is left is the car body itself.
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### Author:  [@astro](https://boards.straightdope.com/u/astro)
#### Post date: [April 5, 2015, 2:29am UTC](https://boards.straightdope.com/t/re-car-shredding-machine-videos-how-do-they-sort-out-that-mixed-up-plastic-metal-glass-scrap/716844/6 "2015-04-05T02:29:11Z")
> [@electronbee](#):
>
> i think the engine blocks have been removed as well as the rims, axles, rotors, transmissions. The only part that is left is the car body itself.
Look a the last minute of the second video aren’t those engine blocks being shredded?
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### Author:  [@JKilez](https://boards.straightdope.com/u/JKilez)
#### Post date: [April 5, 2015, 2:33am UTC](https://boards.straightdope.com/t/re-car-shredding-machine-videos-how-do-they-sort-out-that-mixed-up-plastic-metal-glass-scrap/716844/7 "2015-04-05T02:33:48Z")
> [@electronbee](#):
>
> i think the engine blocks have been removed as well as the rims, axles, rotors, transmissions. The only part that is left is the car body itself.
Except (in the second video) you can clearly see axles on some cars, and the machine does a whole group of nothing but engine blocks at the end, apparently as a palate cleanser. It definitely has some impressive power.