coating 80# stock on a SM74

[Maddawgjoe]

trying to Aqueous coat 80# gloss stock, has anyone done this successfully?

The problem I am having is that it will not stack in delivery. we ran some sheets without coating and no problems, stacked perfect. started coating again, didnt stack. I have tried no vac. on slow down belts, min. air from long. tubes and fans at full speed, and all other variations. we did a job a year ago on 70# gloss and same probs, but it was only 3500 imps. this 80# is 135,000 imps.

[turbotom1052]

have you tried your sheet decurler? we coat 70# coated sheets all the time. Sometimes even 60#. The 70# can usually be made to jog with relative ease but the 60# is always a challenge. This is what i suggest....
1 if possible put a base of well jogged stock in your delivery about an inch high to get
started. Its alot easier to maintain a decent jog once youve got a little headstart!!!

2 make sure your coating is of the right consistency by measuring with a zahn cup

3 Try to use a combination of slow speeds on your slowdown wheels, along with a late
sheet release to S T R E T C H the sheet out as its deposited on the top of your pile that should be running high up so as to shorten the drop to the top
of the pile. The longer the sheet is dangling in mid air the greater the chance of it curling up on the tail and not jogging

4 use minimum fan speeds and be sure to locate a bank of fans just in front of your
slowdown wheels or belts. I also like to use the center blowdown tube to break the
sheet a bit in the middle.

5 engage the sheet decurler and use just enough vacuum to flatten the sheet out in the
tail.

6 slow the press down!!!

once youve got the sheets delivering well you can inch up on the speed a little at a time making the fine adjustments as you go. I also would recommend using the wide wedges on all four corners as opposed to the thinner ones. I think that if you can just get the thing going and jogging at slow speed then once the tack of your ink and coating settle down you can speed things up a bit. You would be wise to push the limits of your load heights. You dont want to go through the entire startup process every time you change the delivery load. If you should begin to loose your jog then stop the press and pull the unjogged sheets out of the delivery and start again. You need to always start out with a good jog to have it continue!!!