Material Question: Polymide

[Dennis Muhlestein]

When you print with an online service, they offer what they call Polyamide a lot and it is an order of magnitude cheaper than if you want to print in ABS.  Can someone shed some light on what exactly they're printing with?  I searched a bit and the references I found said it was more like Nylon.  In fact the reprap wiki actually shows people trying out printing with weed trimmer line.  Hm, interesting.  Anyway, that doesn't seem quite in line with what you get if you order a part and they print it in Polyamide though.  Would love to learn more.

TIA.

[Ryan Carlyle]

All nylons are polyamide polymers. That's the name for the class of compound. The specific type (nylon 6, nylon 11, etc) refers to the type of precursor chemical used to make the polyamide polymer. 

I don't know why it would be cheaper to print than ABS.

[Dennis Muhlestein]

Here is the page on i.materialize that talks about their material.

http://i.materialise.com/materials/polyamide

I just realized they're not using FFM but rather laser sintering so that's probably the difference in price.

[Ryan Carlyle]

Oh yeah, that's some kind of nylon. No obvious way to know which type though. Sounds like the laser sintering leaves it pretty porous... which likely isn't terribly strong, but that's speculation.

[Dennis Muhlestein]

Actually I used the service a couple times before I got my own printer.  It's pretty strong.  In fact I have a hard time matching it's strength but I'm printing with ABS not Nylon.  It is porous but not so much that it bothers you.  Doesn't have the feel of ABS.

[Dan Newman]

On 24/09/2014, 2:59 PM, Ryan Carlyle wrote:
> All nylons are polyamide polymers. That's the name for the class of
> compound. The specific type (nylon 6, nylon 11, etc) refers to the type of
> precursor chemical used to make the polyamide polymer.
>
> I don't know why it would be cheaper to print than ABS.

What's the printing process? Some of the powder printers nylon and
related powders.... Problem is, those tend to not be very strong
prints unless you post process them (e.g., infusion of epoxy resin).

Dan

[Dan Newman]

On 24/09/2014, 3:02 PM, Dennis Muhlestein wrote:
> Here is the page on i.materialize that talks about their material.
> http://i.materialise.com/materials/polyamide
>
> I just realized they're not using FFM but rather laser sintering so that's
> probably the difference in price.

Powder process: much weaker than FDM.

Dan

[Dan Newman]

On 24/09/2014, 3:11 PM, Dennis Muhlestein wrote:
> Actually I used the service a couple times before I got my own printer.
> It's pretty strong.

They must have post processed it by doing a resin infusion. Pretty common place.

Dan

[Dennis Muhlestein]

One thing I liked about the parts I got done with that process is that
they had a very nice bottom surface. It's hard to do that with a print
bed and supports. Like for instance, I had a logo on the bottom of a
case for one part. Difficult to print piece but turned out nice with
their process. Best I can do with my printer is to print very high
density support material w/ HIPS or something on the bottom.

[TobyCWood]

A Z corp with gypsum powder maybe, but laser sintered nylon IMO is stronger. A HECK of a lot more expensive to print in and ALOT more work to extract and clean, but it's nylon and not a hint of layering... The surface is the texture of the powder which is what is sintered.

The pics are 2 objects that we just got from shape ways using this approach. The microscope view is of the upper part, not the anvil. It gives a good view of the surface texture.

[Dan Newman]

On 26/09/2014, 9:55 PM, TobyCWood wrote:
> A Z corp with gypsum powder maybe, but laser sintered nylon IMO is
> stronger.

Depends upon the process. Looks like Shapeways is using a process and
nylon for which they do not bother with an epoxy infusion. But there
are other, perhaps older, nylon laser sintering processes where an
epoxy infusion is done. Particularly some of the filled nylons in
which the granule size of the nylon powder is likely larger than
what Shapeways is using.

> A HECK of a lot more expensive to print in and ALOT more work to
> extract and clean,

And the chap I was responding mentioned that the bureau he was
using charged far less for the process than ABS FDM. So possibly
a different sintering process or material than Shapeways is using?

but it's nylon and not a hint of layering...

Keep in mind that Shapeways polishes the beasties afterwords using
a tumbling process. I don't know how much that is to just dislodge
loose and partially bonded material vs. smoothing things out a bit.

Dan