Tuesday, October 30, 2007

 

Wanted: Powdered ABS Plastic

I have an idea I want to try out involving sintering (melting) powdered plastic with a laser as an alternative to extruding plastic from a nozzle. To do this, I need some sort of plastic, ideally ABS plastic that is powdered and will absorb the laser light. I’m guessing it will be an IR laser, but I figure black plastic would be a good bet for this.

Any ideas?

Comments:
I remember seeing some similar dicussions in the candyfab forums: http://www.candyfab.org/
 
Laser printer toner? I don't know what its made out of but is black and fuses with heat.
 
hey james,

yeah, i had the idea after 2 things:

1. reading about candyfab and how they use the powder as both printing material and support

and

2. reading about people taking apart DVD drives to get cheap lasers that can melt/burn plastic.

i was thinking that if you could combine the two, then maybe you could print things in ABS! that would be pretty rad.
 
Printer and copier toner is AFAIK carbon and latex. You can buy copier toner in bulk. No idea what it's like when you fuse it in large quantities.

Another possibility is a powder coat supplier. Not sure if any are ABS-based. Should come in just about any color your want, though.

Hmm, I just found this site. It looks like some place in Staten Island is trying to get rid of ABS waste powder. Pretty cool site. All sorts of scrap material.
 
If it were me, I'd call Jim Waring at New Image and ask him if he used powdered or granule ABS to make his filament and then beg a sample. Failing that I'd get the name of his supplier and beg a sample from them pretty much like we got samples of CAPA.
 
Wouldn't this approach tie us to being supplied by conventional industry? I thought the idea was to keep reprap as self sufficient as possible. Granted, we need to buy in the current feedstock in reels, but I imagine extruding your own rods from melted stock would be much easier than powdering it reliably without contamination or constantly replacing machine parts.
 
steve,

wow... that abs powder site is awesome, but they are selling it in like 10 ton loads. maybe i could beg a sample from them.

forrest,

that sounds like the best bet. i'll give him a call!

tom,

at this point in time the most important thing to do is achieve reliable 3D printings. we're going to be reliant on existing industries for a long while. even when we do achieve full self replication, it will be a while until we have machines to generate feedstock. even then when we have machines to make filament or grind ABS, then we'll still need to get raw materials from somewhere.

also, we've looked into extruding our own filament. its alot harder than simply pushing it out a hole. theres a whole bunch of dynamics that are hard to control. grinding plastic down may turn out to be easier.

personally, i'm fine with buying the raw materials pre-made. they are super cheap and makes our research easier.
 
Ha! I didn't notice the quantities involved. I guess you could always get 199 friends to each take 100lb of it.

I wonder how much room 10 tons of ABS powder would occupy.
 
http://www.instructables.com/id/SQC1X8HF2NOBMSC/

step 6 and lots of time with a bench grinder.
 
That's a thought. Rig up a grinder or ball mill to roll your own.
 
Will a ball mill work on plastic? I can see how it works on something that is brittle, or powders on impact, but the polymers we are dealing with are very tough. They are easy to deform but very difficult to actually sever.

I could see it working if we took the temperature down below the glass transition temp but not otherwise. Anybody tried it?
 
Solvay creates powdered CAPA resin by cryogenically chilling the plastic before grinding it. They use liquid nitrogen, iirc.
 
This might have relevance.

I've been reading the blogs and forums here for a couple of months now and actually came up with the same idea. This a pretty cool place with lots of info. Good job.
 
Actually I think ABS has Tg above room temp so a ball mill might work.
 
This article mentions using a coffee grinder.
 
I just looked at the linked site mentioned in the article. They're doing essentially the same thing as Zach suggested except they appear to be using a nichrome wire probe instead of a laser.
 
Hi,

I tend to lurk here and at Candyfab. One of the things they've discussed there is using plastic blasting media for a sandblaster. If you shop around you should be able to find it in very high grit values and at pretty cheap prices per 50lb bag. Just be careful not to get urea based plastic media. Apparently, its not a thermoplastic. Also, you'll want to make sure you get an opaque color as you're looking to use a laser and you'll want it to absorb as much of the light as possible.

Consequently, the guys at Candyfab also discussed the possibility of using focused light instead of a true laser. It has the advantage of being somewhat less dangerous to play around with than a laser as the light is only focused at one point in space then diverges. A laser like the one you talked about getting from a DVD player can cause permanent eye injury or blindness just from indirect reflections of it's beam long before your body can physically blink.

Good luck and make sure you get adequate eye protection for the proper wavelength laser you play with.kfe
 
Good idea, sblaszak. I personally wouldn't be too comfortable messing around with lasers capable of that kind of damage and, besides, a parabolic reflector for a heat lamp or something would probably be way easier to make.
 
Another possibility might be to buy a dozen or so cheaper and weaker lasers, and arrange them around a cone on the printing head so that their beams intersect at the desired burn point.
 
hey, thanks for all the great suggestions guys!

i found a place that sells the 250mW laser diodes + housing + power circuit for $50. i ordered that, and it should get here next week. that will save me the time and effort of actually having to try and extract a diode manually.

secondly, i googled around and did some general sleuthing. following steve's suggestion of powder coating, i found an online store that sells powder coating powder. here's the link:

http://www.absolutepowdercoating.com/

according to the site, its a Polyester based powder coat. its not ABS, but maybe it will still work. i guess i'm about to find out =)
 
What about extruding an acetone-polystyrene(Styrofoam) mix while heating it a bit with a laser as it's laid down? the Styrofoam will break down into a blob and will harden once the acetone evaporates, which I'd imagine would be much quicker with the laser. You'd probably want to be in a well ventilated area and what not. Would that even work? I'd imagine with the right acetone/polystyrene ratio, you'd be able to develop a suitable viscosity and extrude it satisfactorily. Of course, I have done about zero research on that and certainly haven't tried it...yet.
 
Hi, Zach:

I've bee doing research on a powder based ( SLS ) system also, glad to see someone else looking into it too!

one detail to keep in mind about SLS -- most commercial systems perform the process in a heated chamber for two reasons:

1. reduces the energy needed to melt the powder, and

2. allows the finished part to cool gradually to anneal it and remove internal stresses to avoid warping and cracking

You might check out google patents. Cool enough, all of the commercial system vendors have documented how their systems work in their various patent applications, and they are free to read....
 
Hi Zach,

... what's with solving plastics-foam, as styropor/polystyrol or others with acetone?

Then you mustn't file a block but simply pour some acetone on the foam and it melts down to a solvent.

When the acetone dries away or you heat it with an laser or heater, then the solved plastic solidify ...

Viktor
 
Hey, if you can sinter it with a laser, you can probably ablate it too; that gives you a lathe of sorts, and one that doesn't need a massive structural stiffening to keep the work from twisting.
 
Hi, Zach:

did you end up getting in touch with the guy with the tons of abs powder?

and, were you able to try the power coat powder?

I've got a 3W IR laser, and as soon as I get my power supply i'm going to experiement with some materials myself...
 
Judging from the age of the last post and no follow ups, I assume not much success with this technique?

or are there any interesting findings? :-)
 
I am currently building my design for a custom home built SLS printer right now.

Does anyone know if a successful attempt at a home made SLS has been accomplished yet?

I plan on ordering a 30 - 50 watt CO2 laser tube and building the cooling and power supply for this. Then, using a mix of RepRap and CandyFab technologies to get it up and running.

With that in mind, I will likely open up a new support board to start getting anyone interested in this project involved.

Thoughts on this from anyone?
 
Typical Toner is Polyester fines, carbon black or iron oxide or manganese oxide, and styrene. Some may contain Polyethylene fines. I have not seen any with ABS. You might want to try toner cartridge refillers. They may have surplus from emptying the cartridges.
 
Talking to my father in law who is retired mechanical engineer. He said that powdered metal is made with the following process. Take molten metal and under pressure eject it through a small nozzle. This creates small particles. You have the ejection on.top of or in a bath of water so the particles cool and don't bind to none another. He suggested that you may be able.to.do.the same with plastic.
 
Do you think an ABS-Acetone solution is runny enough to attempt the above using an airbrush?

 
You can make it as runny as you want by adding more acetone.
 
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