PLA, ABS, and ASA are three of the most commonly used plastics in 3D printing. However, although all three are thermoplastic polymers (they flow when heat is applied) that can be printed with varying degrees of ease, they have very different properties that determine their applications.
Polylactic acid (PLA) comes from natural sources such as starch and is also biodegradable, making it unrivalled in terms of sustainability compared to its two competitors, which are derived from petroleum. Other advantages of PLA are its ease of processing (lower extrusion temperature) and good surface finish, especially for aesthetic parts. However, its mechanical properties are limited, especially when PLA is subjected to temperatures as low as 55-60 °C.
Acrylonitrile butadiene styrene (ABS) is composed of three different monomers, each of which contributes certain properties. Overall, ABS has a good set of properties such as strength, flexibility and durability. Furthermore, its heat resistance is much higher than PLA, which means it can be used in a much wider range of operating conditions. This is why ABS is replacing PLA and why we at Addimen recommend it, especially for parts with any mechanical requirements, however low they may be. The slight additional cost of the material is fully justified in most cases. However, ABS is prone to warping and cracking if the process temperatures (bed, chamber and extruder) are not properly controlled.
Another factor to consider is that ABS is soluble in acetone, making it easy to polish parts made from this material. Thus, although PLA comes out of the extruder with a better surface finish, ABS and ASA can be improved in appearance using acetone vapours.
To conclude the comparison, acrylate, styrene and acrylonitrile (ASA) has properties very similar to ABS but is particularly resistant to weathering, sunlight, saturated hydrocarbons, oils, aqueous salt solutions and some alcohols. Therefore, the additional cost of using ASA instead of ABS is only justified when the part will be exposed to the elements mentioned above.
A common feature of ABS and ASA is that they release small amounts of styrene during printing. This factor means that printing with these materials must be done in well-ventilated rooms.
