RapidPro 2015, why do we print in ABS ?

We are back from RapidPro 2015…

SpiderBot Booth at RapidPro 2015

I am impressed by the number of people we have seen and that have shown a great interest in our 3D Printer, the SpiderBot. On a personal note, I would like to thank the hundreds of visitors who stopped at our booth, to talk, ask question and express their interest.
 One of the things that surprised me was that a lot of visitors were wondering why we were printing in ABS !
It would seem that not many people are aware that PLA can not be used beyond 55/60°C and the parts soften and deform from this temperature onward.For this reason, I would like to share some more of the technical reason behind this choice…The Glass Transition(Tg) of the PLA is about 60°C as measured in the Differential Scanning Calorimetry (DSC) we made, see image 1 (click on the image to enlarge). DSC is a thermal analysis technique, to properly determine the phase transitions: Solid, Glass Transition, Melted/Liquid of a materials when exposed to a temperature range.

DSC of PLA Glass Transition (Tg) and Melting point

Image 1 PLA Properties over temperature range Between ~58°C and the melting point (about 167°C in the DSC above) PLA is in an unstable and uncontrollable state. If we closely analyze the DSC curve above, the beginning of the Glass Transition curve even starts from 47°C (Left Limit).For this reason, we recommend to not use PLA if your parts are subject to be exposed at more than 50°C and not leave your PLA parts near a window or in your car during the summer ! Comparing with the DSC of ABS, we see that the glass transition is ~107°C with a transition curve beginning around 95°C (see image2 below).

DSC of ABS Glass Transition (Tg)

Image 2 ABS Properties over temperature rangeNote that this DSC of ABS has been made up to 160°C, the actual melting point of ABS is not present in this graphic. Due to these properties, ABS is a much more reasonable choice for industrial parts or parts that are subject to be used in « real life ». Happy printing!