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PLA and ABS are the two most used plastics in the personal 3D printing market, constituting about 75% of the current market, due in large part to their good printability. So it is no surprise that many of filament companies want to keep the same base chemistry but improve the properties of these materials. In our first study on filament providers, we tested a few modified filaments and found that while the visual quality of these filaments was better, their mechanical performance was actually reduced by the modifications.
How about PLA and ABS filaments that have been modified to improve mechanical performance or processability? What is the extent of the improvement compared to the base chemistries? What is the impact of these improvements on visual quality?
In this study we first lay out the pros and cons of basic PLA and basic ABS, and then we use our testing procedure to show how improved filaments compare in terms of performance, quality and process.
Summary of findings
Note: Please bear in mind that all filaments, PLA and ABS alike, are graded on the same scale. Therefore the grades both represent the assessment of the supplier and the specificities of the chemistry. In the results tables, we split PLA and ABS filaments to provide two reading levels, and we also explain in the study what is linked to the chemistry and what is linked to the supplier.
Here are the high-level results from our study:
The study shows that it is possible to improve upon basic PLA and ABS characteristics, but the conclusions vary depending on the product tested. Some filaments we studied manage to improve one or two criteria while remaining on par with the benchmark for the other criteria, some filaments improve one criterion but have to sacrifice the other ones to do so, while others just don’t behave much differently from the basic chemistry.
Polymaker provides a great, balanced modified PLA with PolyMax: it keeps a tensile strength close to regular PLA and provides great visual quality, but at the same time it has the high impact resistance of an ABS. The processability is also very good.
Formfutura’s ABS pro has amazing mechanical properties: good tensile strength and elongation at break, and an impact resistance 2x higher than the next best ABS. Quite surprisingly, it also excels in quality, which is a stunning achievement for an ABS. The only difficulty is in the process, where adhesion issues prevent easy printing.
Orbitech and Push Plastic have done well improving the processability of their filament, but this has decreased mechanical performance: lower tensile strength for Push Plastic’s Premium PLA, and lower impact resistance for Orbitech’s Smart ABS. In addition, while Push Plastic’s filament retains good visual quality, Orbitech’s filament had the lowest visual quality of this product selection.
Formfutura’s Clearscent has also improved the printability, and is otherwise a fairly standard ABS. Their EasyFil is a fine ABS filament but doesn’t really stand out compared to a regular ABS such as Village Plastics’.
Introduction to PLA and ABS
In this study we compare improved filaments to regular filaments, but we also compare PLA to ABS. We chose to put both chemistries on the same grading scale because choosing between PLA and ABS is a dilemma that most 3D printing users face, in particular if their machine enables them to print both. This is also a good way to cross-compare an improved PLA with a regular ABS, and an improved ABS with a regular PLA.
We tried to recap why a user would choose one component over the other in the following table:
This provides a base framework for filament suppliers to improve their PLA or ABS filaments. We will see how the filaments studied here address some of these issues.
About the testing procedures
Here are the key evaluation criteria for the performance, quality and process tests:
The tests were carried out while controlling for all environmental parameters, all filaments from the same material being printed on the same printer with the same settings:
Compared to our previous studies, the testing procedure was improved by:
- Testing the impact resistance of the filaments through a Charpy test
- Using a consistent color across all filament suppliers: blue for most, black if blue wasn’t available
- Systematically using multiple temperatures to test quality, to avoid favoring one filament over another just because the temperature is more suitable
- Printing “torture tests” on top of the owl figurines to test geometrical accuracy, based on a procedure that was published in Make magazine
- Doing a test on adhesion for ABS (printing a large rectangle and seeing how much it curls)
Detailed results: Performance test
We performed a tensile test on 3 specimens of each filament, and a Charpy test on 5 specimens of each filament to get the following values:
The tensile tests were carried out with a universal testing machine, at the PIMM lab of the Ecole Nationale Supérieure des Arts et Métiers ParisTech. The impact tests were carried out with a Charpy testing machine at the Conservatoire National des Arts et Métiers. The data were compiled and averaged to build the following table (note: the “low / medium / high” characterization used here is relative within this filament selection and does not represent an absolute assessment):
This set of results shows that PLA filaments have high tensile strength and low impact resistance, while ABS filaments have high impact resistance and low tensile strength. Elongation at break is slightly lower for ABS than PLA, but both are quite low in absolute values (1.5% to 3.5% in this batch), so it is not the most relevant factor here.
The following Ashby plot shows the trade-off between tensile strength and impact resistance, and where improved filaments stand in this framework:
It is interesting to note that no filament is the best in both tensile strength and impact resistance. However, Formfutura’s ABS pro is very impressive since it has a tensile strength close to PLA’s, while also being 2x more resistant to impact than the second best filament of the batch.
The other filament belonging to the “stronger materials” quadrant – although a lot closer to the center – is PolyMax from Polymaker. It is a good balance between the two characteristics, retaining good tensile strength but with a much higher impact resistance than regular PLA.
At the other end of the graph, Premium PLA from Push Plastic and Smart ABS from Orbitech belong to the “weaker materials” quadrant. They have both low tensile strength and low impact resistance.
Finally, Formfutura’s Clearscent and EasyFil show very similar performance to regular ABS with low tensile strength and high impact resistance.
Detailed results: Quality test
For each filament, we printed two owl models (.stl file downloaded from Thingiverse), changing the extrusion temperature between the two prints. Then four people were asked to rank each batch from “best looking” to “worse looking”, and also group them by quality categories.
|We also printed three geometrical objects (see right) based on Make magazine’s testing process one time per filament to test its geometrical accuracy (important for functional parts for example), and adjusted our ratings based on this additional test.|
Based on this testing procedure, the following conclusions were drawn:
Generally, PLA filaments show much better quality than ABS filaments, due to the different nature of the two chemistries. In particular, PLA warps less than ABS and thus makes for increased dimensional accuracy and sharper details.
Polymaker and Push Plastic’s filaments have better accuracy on details than regular PLA filaments. However, in the case of Push Plastic, the improved accuracy comes with a slightly less good visual aspect as the surfaces look and feel rougher.
For ABS, there is not much difference between most improved filaments and the regular ones, at first making us believe that there was no redemption for this chemistry. But ABS pro from Formfutura proves that it is possible to increase the visual quality of an ABS-printed part, as it scored first on the owl test. Geometrical accuracy was slightly lower than some PLA but still very good.
Detailed results: Process test
The assessment of how easy it is to process a given filament depends on one-off issues and is therefore harder to characterize than quality or performance. However, we wanted to point out obvious or recurrent process-related characteristics we observed when using the filaments.
In particular, we gave a better grade if the spool was convenient to use (right dimensions, easy-tie for the filament… etc.), if it was easy to feed into the printer, if the filament was not getting tangled, if the filament sticks well to the platform, and if there was no or limited post-processing needed.
We found that Push Plastic’s Premium PLA, Formfutura’s Clearscent and Orbitech’s Smart ABS are very easy to print and do not curl compared to other filaments.
On the other hand, FormFutura’s ABS pro is hard to keep on the build platform. Esun’s PLA does not have a major problem but we had a succession of small issues that are quite burdensome in the end.
Most other filaments are fine but have the occasional printing problem.
Improved PLA and ABS filaments increase the range of properties that these chemistries can reach, both in terms of mechanical performance and printability. Few, however, manage to bring new properties without compromising other aspects of the filament’s behavior. This shows how materials often work in trade-offs, and that it is difficult for a material to be improved in every way.
It is still the early days of modified PLA and ABS filaments, but the possibilities offered by making composites or using additives with these chemistries are broad and should lead to new applications for Fused Deposit Modeling (FDM) in the next few years.
Beyond PLA and ABS, this study begs the question of whether other chemistries are suitable for the FDM process, such as Nylon or PET. This will be the topic of a future 3D Matter study.
We do not pretend to have an exhaustive and perfect test. In particular, the test does not account for the following parameters:
- Printer specificities: we used only one 3D printer to do the tests and we believe there are some differences depending on the machine used.
- Toxicity: we didn’t measure the toxicity of each filament. There has been studies suggesting that ABS filaments’ ultra-fine particle emissions are higher than PLA’s, but we do not have the capabilities to check such claim.
- Grading divergence: Grades we got on this study can be different from those we get on other studies for the same filament. This is primarily because the grades are relative to the product selection, but also because the printer is different.
 Market interviews
 3D Matter, What is the best PLA filament supplier for my 3D printing needs?, December 2014
 3D Matter, What is the best PLA filament supplier for my 3D printing needs?
 http://makezine.com/2014/11/07/how-to-evaluate-the-2015-make-3dp-test-probes/, November 2014
 Typical material selection graph
 While these materials do not have good mechanical properties, they show excellent printability, in particular due to limited warping (see “Detailed results: Process test”). So the user has the option to raise infill to 100% to compensate their weaker mechanical performance
 Ultrafine particle emissions from desktop 3D printers, Brent Stephens et al., 2013, Atmospheric Environment