Types of Extrusion Systems

Filament Extruders

The most commonly used and versatile type of extruder that utilises spools of thermoplastic filament that are fed into the printer.

Plastic Pellet Extruders

Similar to the filament extruders but using thermoplastic pellets or granules that are fed into a hopper before being melted and fed into the printer.

Paste Extruders

Sometimes left in it's own category as it doesn't use thermoplastics but rather any 'paste' material that can be extruded.

Learn more about paste extruders here in our clay 3D printing learning module!

PLA

+ Excellent visual quality

+ Easy to print with

+ Can be post-processed easily

- Low impact strength

PETG

+ Food Safe*

+ Good strength

+ Easy to print with

+ Recyclable

PVA

+ Water soluble

- Difficult to print with

TPU

+ Very flexible

- Difficult to print accurately

Nylon

+ High strength

+ Excellent wear and chemical resistance

- High fume emissions

- Absorbs Moisture

PP

+ Good impact resistance

+ Good heat resistance

- Warps upon cooling

- Difficult to print

ABS

+ Good strength

+ Good temperature resistance

- More susceptible to warping

- Requires printer to be enclosed

Considerations when Printing

Take note of some of the things that may affect your parts when printing as you may need to make adjustments to your design to incorporate these features.

Part Strength

For functional parts, it is important to consider the application and the direction of the loads. For example, FDM parts are much more likely to delaminate and fracture when placed in tension in the Z direction compared to the XY directions (up to 4-5 times difference tensile strength).

Source: 3D Hubs

Corners

Because FDM printing nozzles are circular, corners and edges have a radius equal to the nozzle size. This means that these features are never perfectly square.

For sharp edges and corners, the first layers of a print are especially important. With each print layer, the nozzle compresses the print material down to improve adhesion. For the initial print layer, this creates a flare often called an “elephant's foot”. Protruding outside the specified dimensions, this flare can impact the ability to assemble FDM parts.

Source: 3D Hubs

Orientation of Parts

The best way to avoid support for holes is by changing the print orientation. Removal of support in horizontal-axis holes can often be difficult, but rotating the build direction 90° eliminates the need for support. For components with multiple holes in different directions, prioritize blind holes, followed by holes with smallest to largest diameters and then the criticality of hole size.

Source: 3D Hubs

STL Files & 3D Printing

An STL is the industry standard file type for 3D printing. It uses a series of triangles to represent the surfaces of a solid model. All modern CAD software will allow you to export their native file format into STL. The 3D model is then converted into machine language (G-code) through a process called “slicing” and is ready to print.

Guide to STL Files

Troubleshoot Common File Errors

Design Interlocking Joints for 3D Printing

Design Snap Fit Joints for 3D Printing