How bad is inter-layer failure with ABS?

[Wade3]

Hi.

I am thinking of moving to ABS, but I want to get something cleared up first.

I have read that the weak part of ABS parts is between layers. So ABS is stronger, but are the layer bonds weaker than PLA, so is it actually weaker in certain ways?

A PLA part that I just had fail was a 3/16 (5mm) diameter post protruding from a base, onto which a snug rotating arm is fixed. I'm not sure if it was from a torsion or straight shearing force, but it seems to have been a layer failure. Does ABS decrease this?

I realize that ABS has better material properties, but that doesn't help me if the layer bonds are weaker, and I am looking for a straight answer to this. Thank you!!

(By the way, in case anyone is wondering, I made the rotating part snug by making a bushing out of semiflex. It's going to be a toy with stiff movable parts. Also, there was a chamfer at the bottom of the post. It broke just above it.)

[Davo]

Two things:

1. Layer separation is a risk with any FDM machine.

2. Layer separation is not an issue with the correct temperature, print speed, and cooling for your layer height and machine.

Well, three:

3. Small considerations when designing the part will make it print more easily and more reliably.

[LambdaFF]

ABS is difficult to print well.

I talked with P Boichut of Spiderbot and in order to print ABS to a high quality standard with good repeatability, he intensely improved his machines : part heater, enclosure, fan to homogeneize temp, heated bed, ... the list is long and the development took time but you can find some info there : http://www.spiderbot.eu/en/products/upgrades.html

And the -impressive- result is there :
http://www.spiderbot.eu/en/media-inf...-pictures.html

Unless you have the means and dedication to strive to such pro results with ABS, why don't you try other high temp materials like PET ? PET is still heat resistant without that goddamned cooling shrinkage that makes it so hard with ABS.

[Davo]

ABS is difficult to print well.

I disagree. I print in ABS nearly every day.

ABS is easy to print with if you are properly set up to print ABS.

ABS is difficult to print with if you are not properly set up to print ABS.

Heating the chamber definitely helps when printing ABS.

[Sebastian Finke]

Heating the chamber definitely helps when printing ABS.

I agree with this. On the flip side I have read that steppers shouldn't be run over 80 degrees C as too high a temp can damage them. Not sure how true this is.

[Marm]

I have found post-production with Acetone or Acetone/ABS slurry applied with a brush greatly strengthens the layer bonds.

[EagleSeven]

ABS Warps more than PLA ,
very obvious difference when doing large base area objects.

[Wade3]

I've got a Craftbot with a heated build plate, insulated bed, glass plate with glue stick, and heating chamber in the works. My original question stands:


Does ABS have weak layer bonds compared to PLA?


If I stress test an ABS part in shear, will it fail before my PLA part fails?

[tpete61]

Scientifically I can't say but from a practical standpoint I see no difference.
If my printer and software are tweaked correctly they both print the same. It takes a little more work to get ABS to be just right but is worth the effort in my opinion.

[jimc]

If you need a strong plastic with extreme layer bonding then petg is for you. Generally there are no layers when its done. The stuff fuses better than any other plastic we can run through our printers. Stronger than abs and temp falls between pla and abs.