Polypropylene

Hi,

I'm about to order some material here in Israel, and the plastic company we work with didn't have ABS but they recommended polypropylene.

They said it had a melting point of about 100 degrees celsius (I think they were slightly off here).

Like a good forume member I searched the forum for "polypropylene" and came up with Forrest's post here: [forums.reprap.org]

So I was a little dismayed but I went on a little search and found that wikipedia listed the melting point as "~160c"

and this website:
[www.ides.com]

Has a very intertesing figure called "Nozzle Temperature (

I'd be very wary about ordering a bunch of polypropylene. I was able to extrude it using a modified Mk II extruder, but not reliably enough that I could ever do any serious printing with it. Mind, I was using homopolypropylene, which has a particularly high barrel pressure requirement.
>
>So I was a little dismayed but I went on a little search and found that wikipedia
> listed the melting point as "~160c
>
That's about right. It doesn't, however, extrude easily until you are quite a bit hotter than that.

I frankly think that you'd be making a mistake unless you are committed to figuring out how to extrude polypropylene and wouldn't mind spending a lot of money finding out. I've been working with HDPE that way, mind, but I still haven't got acceptable results with that plastic.

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Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison

The ides data is for injection moulding which is quite different. I have found you need to extrude at around twice the melting point minus the temperature of the layer below in order to form a weld. For big objects that would mean about 300C for PP unless you heated the bed. I am not sure whether it would start to decompose at that temperature. Probably better to heat the bed to about 60C and extrude at 240C.

Still it needs somebody to try it to be sure. PP should be good for making flexible things like living hinges.

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[www.hydraraptor.blogspot.com]

>
> Still it needs somebody to try it to be sure. PP should be good for
> making flexible things like living hinges.
>
I'm attracted to it for much the same reason. It's also the cheapest regularly available polymer out there.

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Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison

Thanks guys, the most help is knowing that PP is not the holy grail they were toting it to be.

I will be needing something to test my extruder when it's ready anyway, so I think i'll call them up and ask for a sample of the plastics they have. (they also carry PE).

After some tests I should be able to find out if something stands out as easiest to use.

Thanks again!

-Leav

This is as far as I have got with PP. Printed on to a PP base with no raft, temperatures were up at 240DegC.

Tony

Wow! So what kind of extruder are you using?

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Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison

Hi Forrest,

All the recent parts have been produced using a BfB extruder with the twin motors, the same one you commented on when I posted the video clip of the working machine. The extruder has remained more or less unchanged. I have changed the hot end a couple of times to get a more consistent filament. The final version has now been in use for many hours of printing being very reliable and giving a consistent print quality. If there is interest I will blog a few details on what works and what does not on the BfB design. Either way any experience I have had on the BfB design has been fed back to them to assess for future versions.

To be honest I did not post anything on PP as the results are poor compared to PLA (pic attached)and PCL prints.

I have only had a couple of hours printing with PP, its not the easiest material to work with. The small PP board I used to print on was a mess by the end of testing, it had so many bits of PP welded into the surface it was hard to find a flat bit to continue testing! When I did arrive at a good setup the resulting print was very strong and durable, however, the surface finish of the object was not so good.

The kids have several large boxes of sweets for Christmas, all in nice PP containers with large round and flat PP lids. I already organized for them to come my way when they polish off the contents!
When the new printing boards arrive I am sure that we can get some

Edited 1 time(s). Last edit at 12/24/2008 10:51AM by tofletcher.

tofletcher Wrote:
>
> All the recent parts have been produced using a
> BfB extruder with the twin motors, the same one
> you commented on when I posted the video clip of
> the working machine. The extruder has remained
> more or less unchanged. I have changed the hot end
> a couple of times to get a more consistent
> filament. The final version has now been in use
> for many hours of printing being very reliable and
> giving a consistent print quality. If there is
> interest I will blog a few details on what works
> and what does not on the BfB design. Either way
> any experience I have had on the BfB design has
> been fed back to them to assess for future
> versions.
>
So how many hours of printing did you do with polypropylene?
>
> To be honest I did not post anything on PP as the
> results are poor compared to PLA (pic attached)and
> PCL prints.
>
That is foolish. ANY results are important. Till you just said, I didn't know that anybody had even TRIED to print with polypropylene, much less managed to do so successfully!

Just looking at your pics it looks like you are needing to be running a bit hotter.

Have you tried any wider prints to see how warping is?

> I have only had a couple of hours printing with
> PP, its not the easiest material to work with. The
> small PP board I used to print on was a mess by
> the end of testing, it had so many bits of PP
> welded into the surface it was hard to find a flat
> bit to continue testing! When I did arrive at a
> good setup the resulting print was very strong and
> durable, however, the surface finish of the object
> was not so good.
>
> The kids have several large boxes of sweets for
> Christmas, all in nice PP containers with large
> round and flat PP lids. I already organized for
> them to come my way when they polish off the
> contents!
> When the new printing boards arrive I am sure that
> we can get some

---

-------------------------------------------------------

Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison

Forrest,

Only a couple of hours actual printing with PP. Maybe half a day including trying to get a set-up that worked.

I had four materials arrive at the same time, PCL, PLA, PP and Polycarbonate. I quickly tried each through the machine and chose to go with PCL and PLA for initial development. Main reasons for this were temperature. Polycarbonate was too high period(but will extrude and does show potential). PP was borderline in my opinion, I think you are correct, I am sure a bit higher temperature is called for. My extruder will not go above 250(at the tip) without starting to produce toxic smoke! The next hot end will go well over 300 so that

Hi

I would be interested in a Blog of what works or not on the BfB extruder.

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Regards

Ian

Tony, you have a lot of good results to show of. They don't need to be perfect according to your standards

I'd also really like to see a wide range of plastics being supported by a RepRap. It really beats the hell out of the limited set of stratasys materials (al though you can order many colors and some variations, it's all very expensive).

We'd still like try to replicate your rapid prototyping results.

If you have hints to improve the BfB extruder, that would be great if you can share them. It would be interesting to know where you deviated from standard instructions...

The extruder is a critical part for any fabbing, any I think many of us don't get it working satisfactory. I'm working with someone with a latte to produce an extruder with a shorter temperature gradient. Right now it seems that the filament gets stuck when it melts inside the PTFE temperature barrier. At that point my drive screw just eats away the filament until it no longer pushes it downward.

I think I'm going to order PP too. The pictures from Tony surely don't get me discouraged! Besides, at some point with the recycling possibility it would be another free material that you essentially get for free with packaging (which would normally just add to our waste).

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Regards,

Erik de Bruijn
[Ultimaker.com] - [blog.erikdebruijn.nl]

Sorry for the slow response, all my spare time has been taken doing finishing touches to the firmware on the new V3 laser cut machine.

Regarding the extruder, I will try and put a few notes together over the next few days and post on the builders blog.

Tony

Tony,
I have a requirement for a transparent material that does not have a low melting point. It is to replace a broken polycarbonate clip in a friend's lamp shade.

What form was your polycarbonate in? Is it flexible enough to spool or does it have to be rod?

Where did you get it from?

Did you get as far as making it to bond with itself?

Chris

Edited 1 time(s). Last edit at 01/27/2009 05:20AM by nophead.

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[www.hydraraptor.blogspot.com]

tofletcher Wrote:
-------------------------------------------------------
>
> I had four materials arrive at the same time, PCL,
> PLA, PP and Polycarbonate. I quickly tried each
> through the machine and chose to go with PCL and
> PLA for initial development.
>
I really missed this before! Who did you buy your PCL from?

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-------------------------------------------------------

Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison

Hi Chris, the PP and PCL both came from BfB, I am sure Ian still has both materials in stock.
The PP is in 3mm filament x 100m coil.
The material is very flexible and tough.
As for getting it to bond with itself - have a look at the pictures I posted in this blog. You can just about see how the layers are melted together. The resulting mini mug is very tough, it will flex across the rim with a very tight squeeze.

OK with that said, the mini mug was a one off, I ran out of room to print anything further. Since the mini mug I have tried to repeat the test and failed miserably. I got the temperature too low, the motor started and jacked the hot end off the extruder! Also worth a note is that the PP is like no other material I have tried, it seems to exhibit a lot of die swell and is a strange consistency when hot, almost rubber like in quality. Its worth doing a series of tests on this material to see what it takes to get a consistent filament. Your help would be appreciated.
Chris, I have most of a 100m coil here, if you drop me an address off-line I will stick a few meters in the post for you to try.

Forest

Tony,
Thanks for the info and offer of PP. I will take you up on that, but it was actually PC (polycarbonate) I was enquiring about.

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[www.hydraraptor.blogspot.com]

Sorry about the mix up Chris, the polycarbonate is in 3mm x 2m coils, again Ian at BfB supplied it. First test suggests this could be a good material for extrusion. High temperature but a nice clean filament. I did not try to print so
I have no idea on how it bonds to itself.

The filament is in a coil that fits into an A5 envelope so quite flexible. I only have the one length that will be run at some point.
Let me know when you want to try the PP.
Tony

I have created 2018 Polypropylene guide would be helpful before buying like you could get all the information properties, types etc here is the complete guide https://omnexus.specialchem.com/selection-guide/advanced-guide-on-polypropylene