Foil Tear Away
Background - We are working more with foil and trying to fine tune our foil release. Most of our work is 4 x 6 or less and now large foil blocking or coverage areas with reverses. We have a Windmill with copper dies running are slowest speed possible the increase dwell time. We use Infinity foil MX or MH release both designed for easy release and the materials we are using. Our controller is an older Boss Unit made by Watlow, so we use Watlow rods. We do a good enough job the foil seats to the material. We use Lettra, Classic Crest, Sundance and label stocks. We raise or lower temps and pressure until we get a consistent foiled seated without using to much pressure. Our tear away is OK and the product looks fine and no one has complained so I am probably over thinking this but I want to fine tune it if I can to make it better.
The Question - How can I better control tear away? More pressure? More heat less pressure? Less heat more pressure? I know the smooth calendared stocks work best since the foil has the easiest time of adhering and pulling away but I wonder what to do on a stock like Lettra that takes more pressure to secure the foil.
Buy a Kluge stamper. They have the air blasts. But seriously, we used more than one brand of foil, and we tried everything you have. Sometimes, we just ended up wiping each sheet after the run. Other times we were able to fatten up the type if it reversed to get a cleaner look. We did all of our foiling on 3 10 x 15’s and 1 13 x 18 stamper. All of it on 1” rolls, running sideways across the form for the 10 x 15’s.
One thing that comes to mind in your situation is press speed. You say you run the press at the slowest possible speed to increase dwell but that increase in dwell may also increase the amount of heat spreading from the die into the adjacent foil. If you ever stop the press with the foil right up next to but not touching a hot die the heat will activate the adhesive on the foil and the resulting print will be a big blob of foil. You might try speeding things up and increasing pressure and or temperature in small increments to keep the foil sticking and see if that helps defeat filling in. Something to try anyway.
Bruce
on my kluges, i have an “air blast” system. it is timed to shoot some air in between the sheet and foil just as press is opening. all kinds of strippers and things you can rig if needed. if you want to send me pics of your problems, i can see if i can help you. another good company for small shops is “General roll leaf” 518-671-6800. you prob end up talking with Brenda, she is very nice and very helpful. (If you just happen to tell her that you got the number from Eric @ southeast Press Service, It would look good for me :0 )They are a broker like Infinity, but have a lot of foils to add to your capabilities.
Ran some infinity on the windmill today; worked very well on top of ink and varnish; both being wax free. I was pretty pleased.
I run slow but seldom at the slowest possible speed, partly as mentioned, to avoid the heat migration.
Fine tune - check. I’m always considering how I might get just a little bit better foil result even when it’s looking good.
Wiping sheets - check. Sometimes it just won’t get perfect. I make sure all areas are getting what they need and wipe one or more area as it is delivered. Just a necessary evil sometimes.
General Roll Leaf - check. That’s our “go to” now that the “big guys” ( can’t recall their name at the moment) have established minimum orders.
FWIW and slightly off topic - I’m not entirely pleased with the mag dies from one the best mentioned die suppliers here on this site. I’ve seen “fat shoulders” on one die. Couldn’t hold open some reverses on a job due to it. Today’s second job had to get pulled off. The shoulders were super steep and the thin parts of twelve/fourteen pt. times were just not there. In traditional film terms I’d say waaay overexposed. Had some other issues as well. I get maybe two dies a month, sometimes two a week. From the outside I think there has been some new hands in their shop/management/workflow.
Thanks for all the feed back. While the tear away is a more of less minor issue we still want to be the best we can be.
Speed - Bruce in terms of speed we actually on purpose spent a whole day resetting our motor and belt the get the slowest speed possible. I never thought about going any faster as I thought it would make the problem worse, so I am going to try running a little faster and see what happens.
Air Blast - I think the windmill has air blast along the rails. I need to see if the air lines are working. It has been along time since I cleared the lines.
The heat migration was something we always wondered about. We generally start low on temp bring it up a little at a time. We actually had more trouble in the beginning with the foil being to close to the die and kind of pre heating the foil. We have the standard undermount foil puller and the foil pulled up and in tight and close to the die. Once we rerolled the foil it put the outside of the roll and further away from the die and it worked a lot better and I got much better tension control
The have played around with the different temps and pressure combinations it all looks OK but since I don’t really know what I am doing I guess I am trying to figure out why it is working and what part is luck and what part is skill.
Follow Up — Today we ran another foil job with very good success. Something a little new to the game. I installed new grippers. My old grippers had broken springs and worn out everything but still worked. One thing I had noticed with the old grippers is the sheet did not want to sit flat. It had a kind of curved approach but would still press flat and foil. I had wondered if part of the battle was getting the sheet to flatten as it was foiling at the same time. With the new grippers that all changed and the in-feed was a smooth transition. I used all you ideas. I cleaned out the air blast, worked with the temp, packing math, quick white cotton glove wipe down and paid more attention to the foil feeder tension. I gave this job more hit than I normally would and result was a much better tear away than I normally get. I think the big improvement was the grippers but also temp and added hit. I have always believed foil need only a kiss hit but now see the advantage to a little more impression and helping break the foil away and any tear away is sort of hidden in the depressed shoulder of the hot.
Foil application happens thru what i know as “the LoveTriangle”. this being said,there are of course all kinds of sub-categories that can matter, IE: ink; varnish; stock; humidity; correct foil ;ETC,ETC.
The “Triangle”, which you seem to have a grasp of, is HEAT, PRESSURE, & TIME.. It takes some of all of these to get foil to work. If one becomes a priority then one or both of the others needs adjustment.
HEAT; is just that, die face temp. realize that each impression takes away some calories from the die. They are restored thru transfer from the heat source. A large die area or slow press speed will transfer much more heat to the stock than small image or higher speed.
PRESSURE: If this becomes a priority as in “No image allowed on the back”,(I have found that hitting against 1500 grit, wet or dry sand paper works very well to reduce image on the back of uncoated stock), then the other 2 need adjustments. uncoated stocks are going to need more pressure to “iron” the fibers into a surface smooth enough to accept full foil coverage. High gloss coated stocks can be “kissed” much more successfully than uncoated. (Lettra or Linen).
TIME: as you have assumed results in “dwell on impression”. it also will keep foil from pre-heating as much. using brown heat tape, and sticking corrugated board ahead of image in line with foil can help insulate the foil to be used.
So, this all being said: increasing press speed may require more heat or more pressure. increasing pressure may allow lower heat. lowering heat may require slowing press down or adding pressure.
Sounds Easy, Eh? lol. get some cheap welding gloves and some burn cream. “Goof-Off” or acetone works well for cleaning up foil where you don’t want it. IE: keep the die clean, even the smallest of items will show up on image, If you stamp your make ready board, clean it off, or replace it. foil, does have thickness and when allowed to build up, will change your pressures. there is so much to say about this. I’m sure other’s will have things too. you will find each job is it’s own challenge with it’s own solutions. Even a re-run can present as a different problem from previous run.
HAVE FUN !!!!
ericm - Thanks for the feed back, all good info and greatly appreciated We had learned or guessed some of what you mentioned. The hard part was knowing what to try and not knowing for sure what might work. Each time it was more of this and less of that and there was not any solid one way of doing it. Now that we know we may need to vary the control elements to achieve success it points us in a direction. Each time we get a little better and we keep a job diary of what we did for each project. It helps to setup for a repeat or run a job of similar specs.
I started a foil job yesterday but couldn’t finish because it got too late. This morning it was like a brand new set up, even though I didn’t change anything last night. This has happened to me before so I’ve always tried to start and finish a foil job on the same day. Also, if it’s a foil and emboss (2 passes), never do it in 2 days. Moisture in the air? Critters in the press that change things?
@ Dennis; Are you shutting heat off end of shift, or leaving it on over nite? What press is involved? how are you locking the dies up? please tell more! :0
Dennis - we have had that happen also on our windmill. Part of our issue was grippers, they had broken spring and were well worn. We just put a new set on. After over night cold temps they did not work quite the same and we are registering to guides. We found the paper had changed by sitting in the open so we started boxing or covering it over night. If the job was small we shrink wrap it to keep the cold and moisture out. We also have portable forced air heaters we will set up around the press for a hour prior to starting to rewarm the metal. Our press is used to running at about 65-80 degrees. When it dropped below that it was not the same machine. We spot oil any moving parts started letting the press idle after it warmed for a while to get is juices ( oil) flowing.
Didn’t mean to hijack this thread.
I always turn the heat off when I leave the shop. It seems safer. I foil on a windmill with 1/4” dies (preferably copper) on a heat plate with the regular die locks. I also use a backing on the heat plate so not to lose heat. Sometimes the positioning will change or the foil won’t lay down the same. Its crazy because I don’t change anything. Not only is the foil a problem but the feeding changes.
411, I like your idea about running the press for awhile before engaging. My shop will get down in the 50’s at night and then my heater will get it up to 70 but I’m sure the press is still cold. My grippers and all other parts are great. I can run hairline registration all day long. The stopping and then starting is the problem. I should pay more attention to the temperature of the shop especially during winter.
When ericm said heat I thought we meant in building now I am not sure. I never leave my hot plate on for long periods with no one around. I finally rebuilt my plate with all new sealed and sheathed rods after first one shorted out and shot a fireball spark at me. I run all equipment partly by sound ( what little hearing I still have) and the windmill sounds different when it’s cold. I may be crazy but the pump ( so vacuum and blower ) sounds different also. It is like warmer air is easier for the pump to move and thus function. Depending humidity and cold paper can change over night. The weather can make the paper go wimpy and not work the overnight. You issue may be a little of both machine and mother nature.
I thought he meant the heat plate.
You mentioned hearing. (Oh no, not another subject) I have a borderline hearing problem. If I wear my hearing aids while running the press, it’s way too LOUD. But if I wear ear protection, I can’t hear the squeaks and sounds of the press, which I think is very important. So it’s no aids and no protection. I don’t hear any difference in my press when it’s cold or hot. haha
i was referring to press heat. if a set up is in question i will turn 280F down to 150 for over nite. you really shouldn’t hear a ton of diff between hot and cold. In, the winter though, I will heat even a basic die cut to 90F. It is what little i can do to stabilize the press year round. We keep the shop at 60F here in the winter. Oiling will change the sound of the press the most.