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Can we use Injection ABS resin?

Posted by rickonvb 
Can we use Injection ABS resin?
August 19, 2014 09:20AM
Hello everyone!

I wonder if there is a problem if we use ABS resin pellets for Injection on our extruders.
I just bought LG380HF resin (their website states that it was made for Injection and not Extrusion).
The thing here is that my filament is coming with bubbles of gas.

the ones that are "bubbles free" can be used without a problem on 3D Printers.

Would it be a problem with this ABS?

Re: Can we use Injection ABS resin?
August 26, 2014 11:41AM
Hi Rick

Yes but only certain grades will work and there are 100s as you no doubt have found out, the only way to find successful ones are to do empirical tests.

The answer to your bubble question is- its water trapped inside, it comes from pellet material ABS which is hydroscopic meaning it absorbs moisture, pellets being small and round have a very high surface area and easily absorb moisture very efficiently, when you heat the pellets and extrude it into filament the moisture turns to steam and expands making a void or bubble inside the filament like you see in your pictures.

The solution- use a different material like PLA which is not as moisture friendly, or dry the ABS pellets, and do it on a dry day, possibly when its sunny-joking that won't work. Try printing with it anyway you may find it will work as long as you nozzle is small, it may not give the best surface quality you may get some little bumps and knots.

I see this a lot in 3mm filament made in China and sold on ebay 1.75mm not so much. All the factories making it of which there are 7 all reside in Southern China where it is very humid, and while they all dry the pellets before they make the filament their final product being bubble free completely relies on factors such as efficiency of the dryers filters which require regular changing, also has the dryer been specified correctly for the throughput, well there is no way of knowing and I doubt they know this themselves because from experience they are not that hot generally on material processing being they are a developing nation and still a bit backward, which is why it is cheap, but not very good, in fact its like the sort of thing your making Rick lol..........sorry I take that back.

While I am on the subject there is a misconception generally that ABS filament suffers dramatically from exposure to moisture during storage, this is a load of bo****ks, the moisture was in it before you even bought it! While it is true there may be some slight surface moisture attracted during storage, this is trivial compared to the moisture which can get inside it during production, it is in fact the consequence of poor quality control and the moisture is inside it from the word go, and not because of poor storage. I have to laugh at those misleading statements on ebay about the dessicant, as if a tiny bag of the stuff will somehow suck out 1000's of bubbles of moisture from inside it, its actually hilarious. Fortunately apart from little blobs and knots on the surface of the print, it is possible to print with heavily moisturised 3mm ABS, as long as the nozzle is no bigger than about 0.4, this is because the pressure build up at the nozzle forces out any volatiles in the melt flow, however if the pressure is not great enough then this cannot happen and you may see some steam occasionally and the surface of the print is not quite perfect, if however you print with larger nozzle sizes you start to get stringing coming and going on the extruded filament which makes horrible prints, this is because in larger nozzle sizes the pressure is lower.

I have tried drying moisture contaminated reels of 3mm ABS, but I am afraid without success, there is just too much too deep inside the filament. An easy test to make to see if you have moisture contaminated filament is to simply place a short length 6" to 7" on a metal tray or some foil, heat for 15 mins (not too long or you will end up with a puddle) or so just above its Tg (120 C) if its got moisture in it you will see lumps on its diameter where the moisture bubbles are, usually they are an inch or so apart along the length, if you cut across the lump you will see the moisture bubble, I enclose a picture of the problem, but yours are pretty good Rick.

Anyone experienced this? Now you know why, solution don't buy that s**t from ebay.

# 500
open | download - moisture in chinese 3mm ABS filament2.jpg (444.5 KB)
open | download - Moisture in chinese 3mm ABS filament1.jpg (459.3 KB)
Re: Can we use Injection ABS resin?
October 26, 2014 03:26AM
Hello there

I've bought some injection modeling ABS pellets here in Croatia,they are form an Italian supplier.Trying to extrude them with ExtrusionBot with no success,they are filled with moisture and the filament comes out bubbly rather then smooth.So i tried to dry them using food dehydrator 4h but no luck,probbably due to moist air its pulling in.So I will also try with a bucket of paint,and an 60w light on the top for a few hours and calcium chlorid (CaCl2) also closed within it to pick up the moisture in the hot air.I tried to put pellets in the oven but it's not an option due to stink(100C) and i'm cooking in it everyday so its not hygenic imho.

So any other ideas for drying except mentioned above?Is it possible to dry them using only silica and no heat, or is silica used mostly for storing them when already dry?
Re: Can we use Injection ABS resin?
October 26, 2014 05:11AM
Put a couple of kilos in an oven at about 50 degrees C to stop stink (100c is way too high) for 1 hour, if they are still wet then put them in for another 1 hours, process immediately after drying. oven drying over long period is the best way. Let me know how you get on.

Edited 1 time(s). Last edit at 10/26/2014 05:15AM by rm2014.

# 500
Re: Can we use Injection ABS resin?
October 27, 2014 04:39AM
For ABS filament, there shall be no moisture if the filament are put into oven at 40-45 degree C for 1-1.5hours,based on our experience.
Re: Can we use Injection ABS resin?
October 27, 2014 09:58PM
Its pretty standard practice to dry the plastic before it goes into the machine. That is to say the machine will not be run if the material is not dry. My materials drying chart recommends ABS for 2-4 hours @ 190f/ or 87 degrees Celsius in a desiccant type dryer. this still depends on material grade. Your resin should have come with a material data sheet. it will state dryer time/temp on it aswell as alot of other useful heat related setting. if it did not come with one I would email your supplier.
Re: Can we use Injection ABS resin?
November 04, 2014 09:27AM
I only have my filament extruder comming in december so I cant say much but i have one question though

What do you ppl think about drying pellets and such in a vacum chamber ?
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