| Subject: |
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Re: Folding 16pp section with perf |
| Name: |
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S Tressed |
| Date Posted: |
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Mar 7, 08 - 12:06 AM |
| Email: |
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STRESSED@SAFE-MAIL.NET |
| Message: |
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Is the perf on the 1st unit wandering or being "pulled" or "stretched" etc... from mainly the 3rd but sometimes the 2nd unit ?
You should shouldn't get this perf being pulled/stretched from a combination KTL or from using a mobile knife on the last fold as the knife folds the section from centre out so any air is expelled on both sides of fold
But on an all buckle folder as the last fold is made the air is squished from the 1st fold edge all the way along and can often stress the signature and the perf is kinda thrown out
Changing the perf is one option to try - often peeps use a massive perf that is more perf than paper so very little is holding the signature together, but this can lead to crow's feet ripples in the perf edge inside
Also the pressure for the 3rd unit 1st rollers should be a little lighter than normal and the rest of the 3rd unit pressures should be a tiny bit on the lighter side to lessen the squishing/throwing out the perf as ot folds
If possible and you have 4 plates in a 3rd unit use plate 3 or plate 4 as often I have found it can reduce crow's feet and stressing of the perf
(but less pressure will produce a spongey fold, but I usually had the good fortune of a pressing unit/stacker on larger folding machines)
If the actual perf is wandering in the first unit, and check this by runing a dozen or so sheets just on the 1st unit only, then hopefully if you are going up plate 1 you could use plate 3 instead to allow more rollers to grip the slippery stock and straighten up the perf a tiny bit by dropping deflector 4
Obviously check all pressures particular the area where the job actualy runs throught the rollers.
if you have a seperate exit roller after the perf/slitter shaft then you could fit some wheels onto that but I prefer to only use exit wheels if i need to
Slitter shaft pressures should not be set too tight either not too heavy that it crease/marks the stock, not too light just moderate pressure I have found works best for me
best of luck |
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