Polylactic acid (PLA) and polyethylene terephthalate glycol (PETG) are two of the most common filaments used in fused deposition modeling (FDM) 3D printing. Both offer distinct advantages and disadvantages depending on the application. This comprehensive guide examines how PLA and PETG differ across key criteria to help you determine which material is best suited for your next 3D printing project.
Overview of PLA and PETG Filaments
PLA filament is made from annually renewable resources like corn starch or sugarcane. It is biodegradable and emits low VOCs when heated. PLA‘s flexibility, low warp, good adhesion, and high detail make it popular for printing models, prototypes, architectural designs, toys, jewelry, and non-food containers.
PETG is a modified form of the PET plastic used to make water bottles. It offers high durability, flexibility, transparency, and temperature resistance. Common PETG applications include mechanical parts, tool handles, chemical piping, enclosures, and other high-stress components.
Material Characteristics: Biodegradable PLA vs Durable PETG
As a thermoplastic polyester, PETG filament contains plastic polymers derived from fossil fuels and chemical processes. This gives PETG superior mechanical properties over PLA, but it is less environmentally friendly.
PLA‘s polylactic acid polymers come from corn-based lactic acid. Though PLA has weaker tensile strength, its renewable nature and innate biodegradability make it better for sustainability. PLA also offers higher precision for small, intricate print jobs.
Research by Sculpteo found PLA to have 49.9 MPa of tensile strength compared to PETG‘s 53.1 MPa. But PETG had nearly 3 times the elongation at break (140% over PLA‘s 4%), confirming PETG as the more flexible and durable option.
Pre-Print Preparation: PLA is Quicker
Both PLA and PETG absorb ambient moisture, requiring filament drying before printing. But PLA can print successfully with some moisture while PETG requires thorough drying for optimal layer adhesion.
PLA also doesn’t need a heated print bed, unlike PETG which demands 70-100°C to avoid warping and splitting. This gives PLA a distinct pre-print speed advantage. Expect to wait 10-30 minutes for proper PETG bed heating before starting a job.
Recommended PLA print temperatures of 180-220°C are easily achieved in under 5 minutes on common desktop printers like the Ender 3. For PETG, printing between 230-260°C means double that warm-up period in most cases.
Printing Process: PETG is More Fickle
Once tuned and calibrated correctly for factors like temperature and retraction, both filaments can produce excellent prints. However, PETG leaves far less room for error than PLA‘s forgiving and versatile nature.
PLA‘s optimal layer adhesion occurs between 190-230°C on the print nozzle. PETG demands precise heat levels from 250-270°C for best performance. Too low, and rough layer lines appear. Too high, and you risk heat degradation in the extruder and clogs.
Higher temperatures also make PETG more vulnerable to stringing, ooze, and blobbing. These defects require more tuning of retraction settings compared to PLA to find the right balance. Using a filament like Overture‘s PETG helps avoid such issues.
For build plate adhesion, 60°C works fine for PLA on the Ender 3, while PETG needs 80-90°C on textured glass for stick — but not so much it won’t release print removal. This fine line makes first layer calibration more difficult with PETG vs PLA’s wider bed heat margin (45-60°C).
Post-Processing: Smoothing and Assembly
Common finishing techniques like sanding, filling, and polishing work well on both PLA and PETG printed parts. However, PLA‘s softer composition tends to be faster and easier during this post-processing stage.
PLA smoothing can be done quickly using household items like dichloromethane vapors or ethyl acetate. Achieving the same superficial polish on printed PETG requires more traditional labor via fine-grit sandpaper and filler primer.
Assembly of multi-part PETG prints also proves trickier. With its extra bonding power, keeping components separate for painting or smoothing is harder compared to weaker PLA adhesions. Support towers may even need tools for removal without damaging the print.
Print Quality: Accuracy vs Strength
Overall print quality differs between PLA and PETG on aesthetic versus functional metrics. For visible accuracy, captured detail, and smooth textures, standard PLA filament can’t be beat.
But where durability and endurance matter most, PETG is king. The thermal/chemical resistance, flexibility, and layer adhesion of quality PETG like Polymaker’s PolyLite line make it ideal for load-bearing prints subjected to stress and environmental factors.
Compare a PLA desk accessory to a PETG car phone mount as an example. The PLA item would likely offer tighter dimensional precision and easier painting for visual quality. But that same print won’t safely hold your phone in hot summer sun while traveling rough roads. Only PETG provides that kind of real-world resilience.
Suitable Applications: Unmatched Versatility
This complementary balance of aesthetics vs mechanical performance informs suitable applications perfectly…
PLA works best for: visual prototypes, scale models, education tools, arts and craft decorations, miniatures gaming terrain, Cosplay accessories, jewelry casting molds, architectural modeling
PETG excels at: functional prototyping, durable end-use parts, chemical/medical equipment, automotive components, outdoor fixtures, tool handles, robotics parts, clear machine guards, cathode ray tube screens, sign lettering
The range of quality materials now available means taking advantage of each technology’s unique strengths. Mixing prints is also popular, like PETG for a durable object core with a PLA shell for easier finishing.
Cost Comparison: Prices are Close
There is little cost difference between quality PLA and PETG filaments. 1KG spools from leading brands generally go for $20-35 despite PETG’s more complex manufacturing. Lesser known companies offer PLA closer to $15-25 per KG.
Budget PETG from generic sources hovers slightly under that, but inconsistent quality often ruins prints. Paying extra dollars per spool for proven filaments like HATCHBOX, Overture, Prusa, or Polymaker will save far more value long run through reduced failed print waste and time.
Conclusion & Recommendations
For most home/hobby 3D printing of non-functional objects, standard PLA remains the smartest choice thanks to its forgiving nature, crisp details, renewable resource composition, low emissions, and recycling potential.
However, advanced users with experience should utilize PETG’s superb mechanical properties whenever prints demand extended outdoor/chemical resistance, dynamic flexibility, high impact protection, or engineering-level performance closer to ABS.
Those new to additive manufacturing are still encouraged to experiment with quality PETG like PolyLite once confident with PLA printing fundamentals. Finding the right slicer profiles to handle PETG’s sticky, stringy tendencies just takes some patience. And having both materials in a printer’s arsenal allows matching the best filament to every application.
