Hi all,

I'm currently running a clear Polycarbonate material using a Fanuc Roboshot injection moulding machine. For some strange reason an intermittent screeching noise occurs during the plasticizing (metering) stage. No problem during the injection (screw forward) stage, only when rotating back. There doesn't seem to be a cyclical pattern to when this noise occurs, there can be no noise at all on some shots and then the screeching noise occurs. When it does occur it can also vary in loudness.

Barrel heats are setup as per resin manufacturers guidelines. Actual melt temperature of material has been checked and seems ok. I've tried increasing barrel temperatures to see if the material might be a factor but this does not help, the same intermittent screeching occurs.

I'd be interested in hearing some of your thoughts on this, and any help would be appreciated. The screw and barrel are relatively new (1 year), so wear shouldn't be a problem.

Thanks in advance,
DM1977