[ Closed ] Filament Extruder - Convert pellets to filament (Page 21 of 58)

where I work we extrude a lot of different materials including  Nylon, PTFE, PVDF & PVDM to name a few.
all our extruders are stainless with a high polish. The nipple we use is rough and the ABS pellets are  abrasive.
I have talked to the Mechanical & Chemical engineers at work and they all say either polish
the pipe ID or go with stainless.

There's no auger wear on mine, but also no particles. It's difficult for me to troubleshoot the issue. Once I have clear ABS (it's enroute to me) maybe I'll start seeing particles, and then be able to troubleshoot.

I ran the new motor for 6 hours tonight, emptying out the hopper and pipe in preparation for the clear ABS.

I suppose it's possible plastic is getting burned, broken up, and forced out later. Not sure if the particles are magnetic or not.

I have an idea that will get rid of the need to cut the pipe with a dremel, and the new motor shafts don't need dremel work either. That would eliminate the need for a dremel, and make the tools necessary just a drill and simple hand tools.

DeParted, what temp are you running the clear at?  I've been having trouble getting the tolerance under .1mm using the spool winder, and I've been using the clear I got from Ebay.  Just running it to the floor is problematic as well.  It has a higher melt flow index than the natural, so it droops a lot coming out of the die rather than curving out like the natural. 

I'll load the natural up again tomorrow and see if its different.   I ran across a plastics expert on an Answer site and asked a couple of questions - http://www.allexperts.com/user.cgi?m=6& … ID=4910925

He recommended a die 2x the filament size with a land 3x the die diameter (land is the depth of the die).   The plastic would be hauled off at a rate that would stretch it down to the desired diameter.  I'm hoping I can get it to work with the natural.  With the clear I was getting about 13"/min.    I took some video of the roller gear and checked the timing of each rotation and it was pretty constant.  I'm guessing the extrusion rate wasn't consistent, which might have something to do with the clear being less viscous.

Good question.

Everything at McMaster I can find in Schedule 40 is claimed to have a seam, though the iron pipes I've been getting don't, so maybe the stainless ones won't either.

There are many, many other suppliers of pipe nipples though. I just haven't done a search.

I ran the clear down to 145 at which point the motor seemed to start having trouble extruding, and the filament still didn't arch like the natural.  This was with a 1/16 die.  I'm interested in seeing what your experience is when you get your clear pellets.

I've been using this as the natural/white:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi … 0843294091

SABIC MG94-NA1000

Which is what I've included in all the beta kits.

The MFR is listed as:
Melt Flow Rate, 220°C/5.0 kg: 12g/10 min ISO 1133 Standards
Melt Flow Rate, 220°C/10.0 kg: 42g/10 min ISO 1133 Standards

Ian, the clear you linked me to is PA-758, which has the following MF properties:

Melt Flow,  220°C/10.0 kg: 34g/10 min ISO 1133 Standards

Not sure how that relates to the MFI you were citing, but it actually seems like the clear should be less "runny", unless I'm reading these sheets wrong.

EDIT: Ah - the MFI you were citing is ASTM D-1238 --- 200°C, 5kg mass placed on top. Just different standards.

http://www.amazon.com/dp/B004XEKNF6/ref … xHash=true

It's hard to say how much better, if any, stainless would be over the nipples we have. I have no idea what alloy is used in the nipples we're currently using, which makes it impossible to compare hardness. 304 stainless is definitely not the hardest stainless alloy, in fact it's one of the softer ones. I can't find nipples in anything other than 304/316, probably since hardness isn't a big factor in transporting fluids.

I will say you could probably get away with a 5 or 6 inch nipple if you use stainless, as it's coefficient of thermal conductivity is about 1/5th that of iron/regular steel. You will have to either shorten the auger or backspace it with washers/more spacers on the thrust bearing mount if you use a shorter nipple.

DeParted, do you have a good magnifine glass and strong magnet?  Have you checked to see if the contaminates are ferromagnetic?

I've seen a speck here and there in the filament, but I haven't run it long enough at a stretch to rule out left over filings from drilling the nozzle.  One source might be burnt plastic.  The corner between the inside of the plug and the inner wall of the coupling is a place where plastic can get trapped and cook for awhile.  Normally extruders have a smooth funnel from the ID of the barrel to the die so there isn't any place the plastic can get trapped.  The plug I have on now is drilled in steps from 1/2" down to the 1/16" hole which extends for just over 1/2".  It isn't completely smooth, there are some small steps between drill sizes and 1/2" doesn't cover the full diameter of the inside face.

I am extruding but haven't dialed in the diameter.  I am also seeing contamination but have only run about 1.5 hours.

Jason

I think I found some 40 micron filters that will work with our design. Cost would be about $3 each. Gonna order some and test.