SoliForum - 3D Printing Community — Inconsistent extrusion when making Polypropylene filament

Re: Inconsistent extrusion when making Polypropylene filament

2017-01-03T23:22:04Z

Elmoret - we're trying to do comparative testing with a printed and injection molded part. The I.M. part is made with the talc filled PP.

BurningRingOfFire - I took a break from the project over the holidays but was working on it again today. So far here's what I've tried:
- Using a nozzle with an increased diameter orifice as well as no filter to reduce flow restriction and increase the extrusion temperature.
- introduced a water bath to cool and solidify the filament faster than the fan can.
- Running the filawinder in manual mode to keep a constant tension on the filament instead of the jerking motion caused when in auto mode.

I'm still struggling to get the initial setup working to a point that I can let it run. Having the filament cooled as it enters the PTFE tube seems to help as long as I can keep the tension consistent until its hooked to the filawinder.

At this point most of my failures were caused by the extruder not maintaining the higher temperature a set it to.
I had the PID set at 215 C and it dropped to around 200C within five minutes of running the screw every time. I'm going to try to insulate it better, but any advice for increasing temp capability and stability?

I've attached a picture of my setup. It's partially operational currently. The white box is the water bath.

Re: Inconsistent extrusion when making Polypropylene filament

2016-12-23T20:32:00Z

Consider this as well: Talc-filled PP and neat unfilled PP are two different beasts when it comes to shrinkage. Talc does stabilize the shrink quite a bit, the tradeoff is differences in flow and melting points.

Re: Inconsistent extrusion when making Polypropylene filament

2016-12-23T20:29:19Z

In my case (modified PP) it can do things that unmodified PETG can't. Chemical and thermal properties that lend it to engineering tasks and specialty applications.

Re: Inconsistent extrusion when making Polypropylene filament

2016-12-23T20:17:14Z

Polypropylene is a beast to turn into filament. It is also quite difficult to print with. Some experiences:

http://www.soliforum.com/topic/5254/loo … p-testers/

http://www.soliforum.com/topic/7881/pol … -filament/

What is your application for PP that that PETG isn't suitable for?

Re: Inconsistent extrusion when making Polypropylene filament

2016-12-23T19:20:10Z

I plan to experiment with this after the holiday.

Some things I recall from operating a large-scale industrial extruder:

**PP doesn't usually require drying however the talc modifier can attract moisture. Spread the material thinly on a cookie sheet and bake at 120-150 degrees in an oven for a few hours.

**Depending on a variety of factors you may need to heat it considerably hotter than "neat" (unfilled) resin. Talc modifies the heat deflection properties and modifies thermal conductivity by a significant factor. It also has a nucleating effect too, which will alter the viscosity.

**I injection mold it starting at 225-230 on an injection molding press you may need to go up around that range to make it work. Maybe even higher because you are trying to pump through such a tiny die.

Hope this helps! Once I get set up to experiment we'll compare notes.

Inconsistent extrusion when making Polypropylene filament

2016-12-23T14:57:52Z

I am having difficulties trying to extrude polypropylene filament. I'm having cooling issues, inconsistent extrusion, and potentially jamming. So far I've tried extruding from 175C-205C with no luck. Ive also tried moving the nozzle fan around and am printing a fan duct to get more precise cooling.

For anyone that's made PP filament, what temp did you find best? I'm using a talc filled PP, so it'll need to be a bit hotter, but a base would be helpful.

Also, did you run into problems with effective cooling, inconsistent diameters, or jamming?

I'm running a 45 degree setup with a filawinder.

Thanks!