Had some production issues today where I was called for paint adhesion issues. I started looking into it and found that it wasn’t paint adhesion but rather plastic cohesion that was failing. I had a look at some other parts and was able to capture this amazing photo of complete peeling.
We had some solvent exposure at work that made for a good picture of solvent embrittlement on PC/ABS. You can see that that once the solvent flashes off you can see the plastic swells up and leaves opaque spots. I started doing some trials where any time there is some molded in stress I run some solvent rags over the part and it directly shows any surface issues. I also did some trials where I left PC/ABS in a can of paint solvent and the plastic completely deteriorated and turned into the consistency of wet cardboard.
While training the new student we started having some production issues with material pulsing that made for a great teaching opportunity. We reviewed the labview monitor and saw significant instability in the flows with overly aggressive controls. During troubleshooting I was able to catch a nice screenshot that showed different control patterns in decreasing aggressiveness. Obviously we still made some adjustments to get it tuned to prevent overshooting at all.
