Composite Filament Fabrication Process
about 1 year ago by email@example.com
Which problem are you trying to solve?
To reduce the ecological impact of waste material generated by society.
How are you going to solve the problem?
By creating composite filaments with waste material and bio-polymers.
What is the impact of your project?
Re-purposing waste material not only improves ecological sustainability, but allows that material to be made useful
again in the form of commercial products. Which eventually may be recycled as well.
How can the project be manufactured in the OpenLab?
BOM: Grinding mechanisms to gain particles sub 200um. Recyclebot(filament fabrication). 3D printers(varying nozzle
sizes). As well as an assortment of bio-polymers for matrix material.
Describe your project in detail
Abstract___The goal of this project is to develop a manufacturing process taking waste material and breaking it down
into sub 200um (80um ideal) particles, then mixing said particles with polymeric material and extruding them as 3D
printable filament to be printed as products. Ideally the materials used for filament would be 100% waste material to
truly promote ecological sustainability of the
Introduction___In general, any material which is stable
(solid and relatively non-reactive) within the temperature range of 0-200C may be used for this project. The particle
waste material is physically bound in the polymer matrix when homogeneously mixed leading to uniform properties. The
properties exhibited by the composite would be a mix between the in-fill material and the polymer matrix. Thus,
different composites may be used for different applications for aesthetic, structural, or other various commercial
reasons. 3D printers are powerful devices for customization and prototyping. Typically, polymer materials are used for
filament due to their low melting temperatures and modest mechanical properties. Two primary benefits are the capability
of user generated content allowed through open source software and the speed at which an idea may be conceived, modeled,
and then printed. Therefore, it is quite appropriate to base the proposed project upon utilization of this innovative
and creativity based technology.
Method___Step one: Waste material
procural – matrix material selection___Of the many waste materials produced by society, there are several which
exhibit superior properties and allow composites of more useful property values (i.e. higher ductility or tensile
strength) to be created. Metals, plastics, and paper products as an example all may be reduced to small particles sizes
relatively easily and would work nicely for this project. Additionally, those three material groups are often waste
materials meaning supply shouldn’t be a concern. Choosing a polymeric matrix material is critical when envisioning
what product will be printed. Some polymers such as poly-lactic acid (PLA) are bio-polymers but degrade in sunlight,
while others such as acrylonitrile butadiene styrene (ABS) are synthetic polymers and do not degrade in sunlight. PLA
and ABS for example could both be used but, ideally for specific waste material composite applications as their material
properties differ. Polymeric waste material may even be taken and used specifically as the matrix material leading to a
100% waste material printable filament. Muti-material or material blends could also be incorporated, but would be more
Step two: Material reduction___To use waste material,
it must be in a physical state capable of being combined with a polymeric matrix and be small enough to be extruded
through a 3D printer. Typical printers have a 0.5mm nozzle size, but 1.0mm nozzles are common for larger prints. As the
clear majority of waste material is greater in size than powders a process to reduce the size of the waste material is
necessary. Several solutions would be industrial grinders, ball mills, grinding mills, or even hand sanders. The general
idea is to go from macro-scale to meso-scale to micro-scale. Particle size should largely influence the bonding of the
filler material to the matrix material. Smaller particle sizes would have less of a chance of clogging a 3D printer
nozzle However, to accommodate larger particle sizes, larger nozzles may be
Step three: Particulate material and matrix mixing__Homogeneous
properties make products reliable and useful. With particulate sizes sub 200 microns, the matrix material ideally would
be of comparable size (but commercially is easily available in pellet form of about 4mm diameter for most 3D printable
polymers). Then the process is effectively to add heat and mechanical forces to mix the two materials and extrude into a
filament. One method would be to use a dual auger system attached to a recyclebot. Each auger feeds in a material to a
heated central auger which then mechanically mixes the materials. After traveling through the central auger, the
combined material is then extruded through a hole(drilled in a metal cap at the tail end of the central auger) of
specific size to create filament of a specific diameter. The now mixed filament leaving the hole end of the recyclebot
then is spooled and then ready for printing. 3mm and 1.75mm filament are typical standards for 3D printers, there may be
benefits to doing one or the other diameter given a particulate size.
Step four: 3D printing a product and optimization of
properties__Depending on printing parameters and 3D printer the part properties change. There are three general steps to
3D printing: One, select a 3D model or stereolithography (STL) file or create one from programs like OpenSCAD or
FreeCAD. Two, import the file into an appropriate slicing software such as Cura or Slic3r and determine the printing
parameters needed for the part application. These printing parameters control the print such as layer height(ex.
0.15mm), printing temperature(ex. 210C), or infill percentage(ex. 25% for normal non-structural). Three, upload the part
via gcode file to the firmware of the printer to be used and print. Several iterations of parts would be needed to
optimize and test printing parameters.
Conclusion and closing
statement__The concept proposed is relatively simple: reduce the size of waste material, find an appropriate matrix
material, heat all materials up and mix together, extrude as filament, and finally print a product. If successful, this
project would effectively allow a significant reusability of waste material. By using both waste polymer and waste
filler particulate material 100% recycled products may be fabricated. Additionally, there is potential for products to
be recycled multiple times within the materials lifetime further extending material reusability. The success of this
project would be a strong step toward a more sustainable and economical future for the biosphere as it emphasizes
specifically a goal of 100% recyclability.