Extrusion variations

Bikeracer
Posts: 135
Joined: Sun Jun 28, 2020 11:54 am

Extrusion variations

Postby Bikeracer » Thu May 06, 2021 8:38 am

I've been using 'Apollox' which is a modified ASA filament, changed over to normal ASA and noticed that the unload and load extrusions have a different diameter.
I'm using the standard 0.4 nozzle as supplied on the E2.

The unloaded 'Apollox' extrusion to clear the nozzle measured 0.6 mm and the loaded ASA that extruded measured 0.5 mm, just wondering if this is normal for two different extrusion widths from the same nozzle ?

I did notice that the 'Apollox' had a poor finish compared to either normal ASA or PLA.

Just waiting for a new reel of '3D FilaPrint ASA X' and will see if the same thing occurs.

Jetguy
Posts: 3227
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Extrusion variations

Postby Jetguy » Fri May 07, 2021 4:58 am

The unloaded 'Apollox' extrusion to clear the nozzle measured 0.6 mm and the loaded ASA that extruded measured 0.5 mm, just wondering if this is normal for two different extrusion widths from the same nozzle ?

Yes, it's called die swell.

Plastic is a polymer chain of modules. You heat it, and this liquid state makes the plastic so it can flow through a nozzle but depending on detail of the plastic (type, fillers, temperature, etc) it has different viscosity but also "shape memory" so when it flows through the nozzle at higher speed, it retains memory of the original size and attempts to expand back to that size. It is different for every roll of plastic, even 2 rolls of the same type but different colors. Again, fillers, colorants, additives, specifics of the polymer, differences in the diameter of the filament going into the extruder, temperature and especially extrusion rate are all variables that change die swell from one extrusion to the next.

Hence why it's long been said for more than 10 years- don't base measurements on extrusion alone from a bare nozzle in the air at a fast rate. Also, just because filament extrudes curls doesn't equal bad or clogged nozzle. It only takes a microscopic defect to make a free air extrusion do anything but go perfectly straight. Under actual printing- you are always using a ratio of layer height LESS than nozzle diameter so the extruded volume is ALWAYS squished and flattened by the trailing edge of the nozzle dragging over it thus plowing it wider.

In other words, a giant red herring, you are looking and worrying about nothing of importance.
Free air extrusion is not an indication.
Actual real world printing result is different than free air extrusion.
Last edited by Jetguy on Fri May 07, 2021 5:10 am, edited 4 times in total.

Jetguy
Posts: 3227
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Extrusion variations

Postby Jetguy » Fri May 07, 2021 5:04 am

https://en.wikipedia.org/wiki/Die_swell
Die swell occurs in instances of polymer extrusion, in which a stream of polymeric material is forced through a die, a specialized tool in manufacturing to shape or cut polymeric materials. Die swell is an instance where a polymer stream is compressed by entrance into a die, and is followed by a partial recovery or “swell” back to the former shape and volume of the polymer after exiting the die, hence the term die swell.

Bikeracer
Posts: 135
Joined: Sun Jun 28, 2020 11:54 am

Re: Extrusion variations

Postby Bikeracer » Fri May 07, 2021 5:40 am

Thanks for the explanation Jetguy.


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