FDM/FFF Materials: ABS and PLA

FDM printer at work

FDM (Fused Deposition Modeling) 3D printing has become the probably most popular 3D printing technology. It is also referred to as FFF (Fused Filament Fabrication). To many, this technology is synonymous with 3D printing. FDM/FFF is simple, cost efficient and the right choice for many hobby applications.
PLA and ABS are by far the most used materials in FDM/FFF 3D printing. ABS is heat-resistant and strong, while PLA, an organic compound, allows more detailed prints.






Material Properties


Please click on the topics of your interest.


PLA 3D printed part

Material sample PLA

PLA:

PLA is a polymer made from organic materials like corn starch. During printing PLA becomes somewhat more liquid than ABS and also gets harder. As a result the prints normally look more detailed than with ABS. Visually, PLA and ABS are very hard to distinguish, with PLA being a little more shiny.



FDM 3D print example engine mount

Material sample ABS

ABS:

ABS is both more heat-resistant and more flexible than PLA. However, ABS can be harder to print, warping in odd ways particularly for large, thin structures. However, ABS is one the most popular materials for both production and prototyping and therefore a popular material for hobby applications and first drafts of conceptual studies.

FDM material PLA

Example: Material Sample PLA

The detail level with FDM is restricted by the nozzle size. While small nozzles allow a greater level of detail, they increase the printing time by multitudes. Typically nozzles with diameter between 300 – 500 µm are used to best balance detail and print time. Layer height usually ranges from 100 – 200 µm, and rarely can be set at 50 µm. As a result the level of detail is rather limited.

In general, PLA allows a bit better details than ABS.

FDM 3D print example ancient art bust

Example FDM/FFF printed art bust; designed by Cosmo Wenman

During FDM the melted plastic is laid down through a round nozzle. As a result small grooves are created between the layers making the surface rough – this is the case for both ABS and PLA. PLA demonstrates better consistency in groove size since the layers adhere together better than ABS.

For the same geometry, PLA is stiffer than ABS. On the other hand ABS has a higher level of chemical resistance than PLA.

PLAABS
Tensile strength, MPa10-7040-50
Elongation at break, %1.5-38015-30
Modulus of elasticity, MPa2,500-4,5001,900-2,700
Flexural Strength, MPa55-8075
Flexural Modulus, MPa2,500-4,0001,700-1,900
Chemical formula PLA

Chemical formula PLA, Source: Wikipedia

Chemical formula ABS

Chemical formula ABS, Source: www.chemgapedia.de

PLA (polylactic acid) is derived from renewable resources such as corn starch, tapioca, or sugarcane. It is produced by polymerizing lactide using several catalysts. PLA is among the most consumed bioplastics in the world. Besides 3D printing, PLA is used in a wide range of applications, ranging from implants to tea bags driven largely by its bio degradability.

ABS (Acrylonitrile butadiene styrene) is famous for its impact resistance and resilience. It is a terpolymer (a copolymer consisting of three monomers), produced by polymerizing styrene and acrylonitrile in the presence of polybutadiene. The proportions of the 3 ingredients vary and are used to create different characteristics of the plastic. ABS is one of the most commonly used plastics and popular in all kind of applications, ranging from consumer goods (e.g. Lego) to the automotive industry.

Warning

Even though many commercialized toys and other products are made of either PLA or ABS, using 3D prints PLA or ABS for toys is not advised. Unless otherwise stated, PLA should not be exposed to temperatures above 50°C. While ABS can resist higher temperatures, it can burn.




3D Printing Process


The FDM / FFF process works by melting a string of plastic and applying it layer-by-layer onto a build platform. Since the plastic is fully melted, with sufficient thickness the 3D printed pieces have similar mechanical characteristics as those from injection molding. Due to the relatively slow printing process the inside of solid models are usually filled with a stabilizing space-fame instead of being printed solid. That space-frame is defined by the Infill Rate – the percentage of the volume which is actually filled with solid material. This is typically set at 20 – 25% of the inside.

For details on the printing process, please visit our page FDM/FFF: Technology Overview.


Visualization of the FDM Method;
Reference: Mohawk College Media; vimeo.com




Finishing Options


Besides basic removal of simple support structures, neither PLA or ABS is normally processed after printing. The surface of ABS parts can be smoothed with Acetone though this will also degrade surface details. Other surface treatment options are available on request.




FDM 3D Printing Costs


The FDM/FFF process involves some manual labor to set-up the printer and remove support material after successful printing. To reflect this we charge a flat set-up fee of EUR 6.00 (including 19% VAT for orders inside the EU). In addition to that there is a charge for the volume of printing material used in both the part and any required support structure. For PLA that charge is EUR 0.50 per cm³ (including 19% VAT for orders inside the EU) and for ABS it is EUR 0.60 per cm³ (including 19% VAT for orders inside the EU).




Wall thickness

Wall thickness: Please allow at least 1 mm wall thickness. For larger areas, it is advisable to increase wall thickness considerably, to prevent warping and potential print failure.

Escape holes

Cavities: Cavities can only be printed, if no support is required. In FDM/FFF, structures are normally filled with a stabilizing space-frame. In case there is a cavity without opening that is crucial for the part, we kindly ask you to mention this in the comment field of your order.

Distance

Clearance Gap: If your file contains two or more close but separate sections, please design at least a 2 mm gap in between, to prevent them from fusing together.

Details

Details: Details should be at least 1 mm in size to be visible. In general, PLA reproduces details better than ABS.

Interlocking

Interlocking objects: You can print interlocking objects, such as movable parts, with FDM/FFF technology. Please allow at least a 1 mm gap between the moving / interlocking parts.

Bounding-Box

Size: The default maximum size of objects is 180 x 180 x 180 mm. Larger objects can be printed on request.




FDM 3D print example candleholder

Decoration

FDM/FFF is increasingly popular for print individualized decorative items. Create your own or download them on 3D print file platforms like Thingiverse.

FDM 3D print example PLA engine mount

Early stage prototypes

3D printing in FDM/FFF is very cost efficient. Given this and the relatively rough surface quality this technology is popular for early versions of design to visualize ideas and understand proportions. In more advanced designs, it is advisable to use more professional technologies like laser sintering, polyjet or stereolithography.

FDM 3D print example hobby applications

Model Making

FDM/FFF is the 3D printing technology of choice for Makers around the world. The wide range of materials, simple set-up, and relatively low cost make this technology appealing to all DIY enthusiasts.

gear wheel PLA

Spare parts

Due to the robust print strength and low cost FDM/FFF is a great technology to produce simple spare parts. Greater access to 3D printing technologies like FDM allow more and more people to effectively repair furniture or expensive appliances rather than discarding them only because a small piece broke.



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