HP Scitex hitting material nearly every print

[Lindquist]

I have a new issue with my HP Scitex FB700.

We are running corrugated plastic blanks, 4 side-by-side. We run thousands of these pieces on a regular basis, but last week the carriage began striking the material closest to the service-end and knocking it out of position as soon as the printing begins.

My initial thought was that we just had a bad palette of corrugated plastic that was warped, probably due to the extreme heat in Texas, but I had another palette brought it and we're having the same problems. The pieces do not appear to be any more warped than usual (corrugated plastic is probably never completely flat).

The immediate solution was to only run 3 prints side-by-side. That eliminated the problem, but it also reduced my output significantly.

I had a technician brought out. We replaced the rails, examined the trolley plate (determined it did not need to be replaced), and then he ran several calibrations. He determined that the media thickness and head height were off and corrected them.

The situation has improved slightly, but it's still striking about 2/3 of the time.

Does anyone have any suggestions on what else we can try?

 

[FrankW]

When loading media, in some settings you can set up the height of the carriage over the media yourself. I can‘t check it out because I‘m at home, but could check tomorrow.

 

[signman315]

Sometimes people will manually input the media thickness and lie to it and tell it that it's higher than it actually is...intuition would say that this would ultimately raise the head height and reduce strikes....but it also raises the height of the input roller and so that roller sits above the material and doesn't press it down, actually resulting in an increase in strikes. So be sure that's not what's going on...sometimes the operator thinks they are helping but it's actually making it worse.

Next thing to check is the "head height off media" this is typically set to a standard .085" but can be raised up to .120"...it does reduce quality some but not terribly and this is the proper weigh to raise the heads. Another possibility would be weak/failing vacuums but I assume your tech checked that.

Also be sure that the head height sensor isn't dirty, again assuming your tech checked that.

Other than that it would be warped material or a bad calibration (which again your tech claimed to have corrected).

The last and longest shot is the data cable running to the head board....they are crap out of the factory and even brand new ones can be faulty (I know from multiple experiences). Give Mike at California Media Services a call, he's a scitex guru and also developed his own data cable that I replaced the OEM cable with and it fixed problems I didn't know I had and I didn't think would be related to the data cable. The data cable could be faulty and passing inaccurate readings from the thickness sensor or other sensors, resulting in a bad calibration or ghost errors. A bad data cable will throw all kinds of errors that aren't actually accurate and you'll be chasing problems that don't exist.

 

[FrankW]

Yes, "Head Height off Media" ist what I have looked for.