1 Topic by kjk3d

  • kjk3d
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Topic: Filament Extruder Design??

I am a senior mechanical engineer at Santa Clara University, and for my senior design project my team is trying to design a filament extruder for a small business in Kampala, Uganda. The end goal is to be able to melt HDPE and PET water bottles and produce a quality filament that can be used to 3D print solar lanterns.

I have been reading some of the threads on the site and I'm learning a ton, but I still have so many questions:

1. What equations did you use to choose the size of your auger/chamber?
2. How do you calculate the melt pressure required for extrusion?
3. Do you have any advice about potential issues I might run into for extruding PET/HDPE plastics?

I have plenty of questions that I need answers for, but I figured it would be best to start out with these 3.

Thanks in advance for any help you can provide as my team tries to design our extrusion machine!

2 Reply by elmoret (edited by elmoret 2013-11-16 00:57:25)

  • elmoret
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Re: Filament Extruder Design??

kjk3d wrote:

1. What equations did you use to choose the size of your auger/chamber?

Like most things in engineering, its a tradeoff. Too small, and you can't feed properly. Too big, and you need a ton of torque. But you knew that already... I hope. smile

kjk3d wrote:

2. How do you calculate the melt pressure required for extrusion?

Depends on the polymer characteristics and desired flowrate. Plenty of texts discuss this in depth.

kjk3d wrote:

3. Do you have any advice about potential issues I might run into for extruding PET/HDPE plastics?

Read, read, and read some more. All of the hobbyist extruder issues have already been conquered by the big guys. No need to reinvent the wheel, just have to resize it.


kjk3d wrote:

3D print solar lanterns.

http://reprap.org/wiki/HDPE
http://umforum.ultimaker.com/index.php? … e-bottles/
Most reports are that HDPE and PET don't print well. Also if recycling, you will have to handle contamination and virgin blending issues.

Good luck!

Filastruder - the robust, inexpensive filament extruder
E3Dv6 All Metal Hotend - the premier 3D printing hotend

3 Reply by kjk3d

  • kjk3d
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Re: Filament Extruder Design??

Thank you for your quick response! We are just starting to look into the design of these machines, and I still have a lot to learn about the extrusion process.

I will have to read some more about the subject before I can ask good technical questions, but one thing I am wondering is -

How much do industrial extrusion equations (with a tapered auger) relate to designing a machine with a normal (non-tapered) screw?

4 Reply by elmoret

  • elmoret
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Re: Filament Extruder Design??

Depends on the equation, and any assumptions made in its use - the texts will cover this too. The math behind it is pretty basic, and can be derived from first principles.

Filastruder - the robust, inexpensive filament extruder
E3Dv6 All Metal Hotend - the premier 3D printing hotend

5 Reply by Hazer

  • Hazer
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Re: Filament Extruder Design??

http://www.slideshare.net/rbplastics/ba … out-screws

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