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Plastic powder trials

Posted by martinprice2004 
Plastic powder trials
March 17, 2010 05:34PM
I have been looking into the problem of producing ABS powder a little further. It appears that industrial plastic powders are produced in a pulverizer. The most common form of this type of machine for plastic seems to use two rotating surfaces such as grinding wheels positioned a set distance apart. The grain size of the powder is set by the distance between the wheels. Rod or plastic shards are fed from above between the wheels, the powder drops out at the bottom.

I have a pedestal grinding machine, so have done a few trials feeding ABS rod into a grinding wheel and to my suprise it didn't melt, but gave off a quite fine powder.
It was in fact very dusty and I really neede a mask.

Perhaps there is some method of using two angle grinders positioned close to each other to control the grain size. I think large diameter wheels may yield better results than a dremmel sized unit.
Re: Plastic powder trials
March 17, 2010 08:04PM
Thanks for letting us know.

I wonder how much contamination there is, and if it would be suitable for Recycler stuff.

I've been thinking about shell mills:
[fficial&client=firefox-a&um=1&ie=UTF-8&ei=XmihS_buOYT0NYWLnesM&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CCYQsAQwAw" target="_blank" rel="nofollow">images.google.ca]

And microplane blades for that:
as well.

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Re: Plastic powder trials
March 18, 2010 04:20AM
... with my experiments on powders and pastes i noticed that spherical particles are much better suitable for both, powder-printing or paste-fabbing.

The simplest way to make micro-spheres is to melt the material to a low viscouse fluid and shot a beam of fluid on a fast rotating disc ... the fluid material is shot away and is reforming in small droplets which can solidify before hitting the walls or ground.

You can/should separate the spheres with sieve filters for uniform size ...

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Re: Plastic powder trials
March 18, 2010 09:08AM
Spraying across a rotating drum is used in the ceramics industry. Fluid slurry is spray dried . It is basically spun across a disk shaped like a "china mans hat" and then falls in a drying atmosphere. The particles are perfectly round and of uniform size. Unfortunately the machine is usually housed in a six storey building!

I think to get ABS to a low viscosity fluid may not be possible as it denatures and chars before very low viscosity is reached.

I think a grinding wheel would contaminate the powder much less than a sanding disk as a grinding wheel is considerably harder so wears much more slowly (producing less contamination).

Just a note on recycling ABS plastic, many plastics have fillers added so they already contain contaminants. This is particularly relevant to automotive products. They can contain carbon filler. It is common for example to use nylon which is glass filled up to around 60%.
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