3d Printing 101(a) – What is PLA?
If you have done any research into 3d prototyping technology, you undoubtedly have come across the litany of acronyms and terminology used to refer to either the 3d printing equipment itself, the materials with which the printer prints, or the characteristics of the printer’s performance. This article is the first in a series called “3d Printing 101” by which we will be educating our readers about various matters they should consider when deciding to proceed with a particular 3d printing technology.
PLA, is a common thermoplastic material used by 3d printers such as the MakerBot®, Reprap®, CubX®, and lower-end desktop 3d printers. The PLA material itself is fed into the prototyping machine in a filament form. The acronym is derived from one of the chemical’s names, PolyLactic Acid. PLA’s popularity for 3d rapid prototyping is derived from its “natural” production (PLA is typically made from cheap starchy vegetables), and its ability to rapidly biodegrade. On an industrial level, PLA is commonly used for food packaging containers.
PLA also lends itself to 3d rapid prototyping as it has a relatively low melting point for a thermoplastic (~157°C, obviating a substantial heating element in the print head) and a reasonable tensile yield strength (~9000psi). PLA is relatively rigid, naturally translucent, shiny, available in a variety of colors, and can be lightly sanded and even machined post-printing.
PLA has some drawbacks, however, depending on the intended use for the part. PLA’s is relatively heat-intolerant, and the material can begin to deform under load starting at about ~130°F. PLA’s rigidity may make it more difficult to use in an assembly. Also, water and high temperatures can lead to the PLA de-polymerizing, physically compromising the part. A PLA part will slowly absorb water from the ambient air: thus, printers must store PLA filaments carefully and users must qualify the purposes for which the part is being made in light of the part’s lack of longevity.
PLA does benefit from the fact that most printers print PLA faster than other materials (e.g., ABS) and the same printer will usually print the same prototype out of PLA more accurately than it would out of other materials (e.g., ABS). Due to its availability, PLA is usually cheaper to print with than other materials. Further, the 3d printing process itself, when involving PLA, does not carry bring with it any odorous fumes: in fact, melted PLA smells almost pleasant.
Overall, PLA is relatively easy with which to print and provide fairly accurate parts, although those parts are not as robust as if they were made from other materials. For a pure “prototype” that will not be subjected to any appreciable physical or thermal loads and will mainly be used as a (dry) show piece, PLA is good material with which to 3d prototype.