Part Failure 1 – Crazing and Cracking

The plastics used in 3D printing behave differently under a constant tension, some are elastic and return to the original shape when that tension is removed, some creep, and take on a new shape as a result of that strain.  Then there’s crazing and cracking which you can see in the print above.

A fine set of cracks initially appear in the plastic, then it finally cracks days, weeks or months later. I find this happens with the plastics that are sold as transparent ABS, even when the stresses are relatively light.  These cracks appear along stress lines, not necessarily along the printed layer lines (which is what I expect to happen with normal ABS).  I do like the appearance of these plastics so I still use them, but I’m careful to avoid using them in situations where I think they’re likely to break.