How do you cut varnish blanket?

Hello Everyone,

In my company, everytime we need to cut the varnish blanket, we do it manually.
But, we have a plotter, but we only use it for cutting packages to show a sample for client. The plotter is from the brand Aristo.
I searched in youtube for a way to cut the blanket in the plotter, and saw some guys doing that, but not so much information.

I'm going to talk with our reseller so he can give us their opinion. But I want yours too, before talking to the guy.

  • I want to know how do you cut the varnish blankets.
  • If you need one specific blade or not.
  • If you cut the blanket and then paste in the plate, or paste in the plate first and then cut the blanket.
  • What is the brand of your plotter.

The reason I want to cut blankets in plotter, is because the plotter is more precise, so he can do the round edges perfectly, and the plotter is more faster than the human hand.
 

Zmeushgo

Registered Users
Hello,

Actually you can use any flatbed plotter for cutting samples for cutting varnish blankets (I suggest that we are talking about cutting resin offset blanket or you mean special varnish blanket material such as Folex Folacoat?). I personaly saw that packaging printing houses cut varnish blankets on Aristo, Kongsberg, Zund, LaserComb, Elcede and other respective brands of flatbed plotters. Some companies uses chinese brands of plotters.

The main you should know the sad and ugly truth (any seller doesn't tell this to you) - the process of cutting varnish blanket (on resin offset blanket) reduce the working resource of any flatbed poltter. So the use of cheaper chinese brand is quite reasonable (it's much more simple to get away of broken chinese plotter and buy new than repair or buy new european plotter)

You don't need any specific blade for cutting varnish blankets, most standard blades for flatbed plotters actually are medical surgical disposable blades and they can be used for cutting most standard thin materials such as paper, carton, self-adhesive paper, different resins, films and so on.

If you cut the blanket and then paste in the plate, or paste in the plate first and then cut the blanket.
Can you explain what you mean? What is the meaning for word "plate" in this phrase?

Hope this helps.
 
Hello,

Actually you can use any flatbed plotter for cutting samples for cutting varnish blankets (I suggest that we are talking about cutting resin offset blanket or you mean special varnish blanket material such as Folex Folacoat?). I personaly saw that packaging printing houses cut varnish blankets on Aristo, Kongsberg, Zund, LaserComb, Elcede and other respective brands of flatbed plotters. Some companies uses chinese brands of plotters.

The main you should know the sad and ugly truth (any seller doesn't tell this to you) - the process of cutting varnish blanket (on resin offset blanket) reduce the working resource of any flatbed poltter. So the use of cheaper chinese brand is quite reasonable (it's much more simple to get away of broken chinese plotter and buy new than repair or buy new european plotter)

You don't need any specific blade for cutting varnish blankets, most standard blades for flatbed plotters actually are medical surgical disposable blades and they can be used for cutting most standard thin materials such as paper, carton, self-adhesive paper, different resins, films and so on.


Can you explain what you mean? What is the meaning for word "plate" in this phrase?

Hope this helps.

I was refering to "resin offset blanket", not "Folex Folacoat".
But with that blanket, we need to then paste above one ctp plate, so the blanket can enter inside the offset machine, and the plate. See the attachment below to understand what I'm saying.
20140716_140800.jpg

Okay, so you say that is possible. But, should I cut the blanket without pasted into plate, or cut the blanket together with plate.

What we do at the moment is just, place the blanket into plate, and then put into offset so the offset will print the job into blanket, then when we can see the job, we cut the holes and things that need to be cutted.
 

Walleye-one

Registered Users
ricreis394,

It looks from your picture, that you are using a "sticky-back" plate material, then mounting it to aluminum plates, back printing the image on press and then cutting our your coating patterns - the same procedure recommended in our KBA press manuals. We had done this in the past, but are now cutting on a Kongsberg table. When we used the sticky-back material, we mounted it to the aluminum plate first then cut the pattern on the table. Word of caution....aluminum does not like to be scored and as much as we adjusted the knife height, we almost always got some sort of scoring on the aluminum - which then of course makes a very weak area for the blanket to come apart on press. We ended up switching to folacoat blankets as scoring the mylar backing is far more forgiving than the aluminum. Cost for us was pretty similar and in my opinion, the folacoat blankets do put a nicer/smoother layer of coating on our sheets.

Now, for the real fun....you will have to distort your coating pattern before you cut it on the table to allow for the growth on press. Here's a useful link/video that shows how to calculate that distortion factor. Flexographic Pre-Press: Calculating Distortion Factors Without a Chart!. You should be able to get assistance from your local blanket vendor as well.

Good luck.
 
ricreis394,

It looks from your picture, that you are using a "sticky-back" plate material, then mounting it to aluminum plates, back printing the image on press and then cutting our your coating patterns - the same procedure recommended in our KBA press manuals. We had done this in the past, but are now cutting on a Kongsberg table. When we used the sticky-back material, we mounted it to the aluminum plate first then cut the pattern on the table. Word of caution....aluminum does not like to be scored and as much as we adjusted the knife height, we almost always got some sort of scoring on the aluminum - which then of course makes a very weak area for the blanket to come apart on press. We ended up switching to folacoat blankets as scoring the mylar backing is far more forgiving than the aluminum. Cost for us was pretty similar and in my opinion, the folacoat blankets do put a nicer/smoother layer of coating on our sheets.

Now, for the real fun....you will have to distort your coating pattern before you cut it on the table to allow for the growth on press. Here's a useful link/video that shows how to calculate that distortion factor. Flexographic Pre-Press: Calculating Distortion Factors Without a Chart!. You should be able to get assistance from your local blanket vendor as well.

Good luck.

Thanks for the reply.

I searched for folacoat blankets on google and youtube, but not found what I want. How do work the procedure to install it on offset machine, since that's not necessary an offset plate (aluminium).
Imagine that I have a machine that uses 1050x750 plate measure, I need to buy folacoat with that measures? So, that way it enter perfectly in the offset?

Folacoat seems interesting, but I want to see more about that.
 

Walleye-one

Registered Users
Thanks for the reply.

I searched for folacoat blankets on google and youtube, but not found what I want. How do work the procedure to install it on offset machine, since that's not necessary an offset plate (aluminium).
Imagine that I have a machine that uses 1050x750 plate measure, I need to buy folacoat with that measures? So, that way it enter perfectly in the offset?

Folacoat seems interesting, but I want to see more about that.

Your press manual should have a specification for the coating blanket size - on our 105cm press we use the same size blanket as our printing plates, but for our 142cm press the blanket is actually 6mm shorter. You will have to do some testing on press to see where the coating image needs to start to line up with the print image - our gripper margin on the printing plates IS NOT the same as the gripper margin on our coating blankets (partially due to the distortion you will have to do) and on our 142cm press we have to flop and rotate the coating pattern due to how the blanket is mounted on the press coating unit.

This will be very press specific and hopefully you have the manuals - or a good manufacturers rep. We actually got a lot of assistance from our coating rep - they should want to help you succeed!

As far as installing on the press, we punch the blankets using the same punch we use on our printing plates. When I cut the blanket, I remove approximately 25mm of blanket material from the gripper and tail and have just the mylar backing left for the press to grip on to.

One last thing, we did to switch to a more compressable packing behind these blankets than what we were using behind the aluminum backed blankets.

Here's a link to some videos from the manufacturer's website - Printing Industry | oneminutefilm.tv (probably the same ones as Zmeushgo) which might show you some of what you're trying to find out - videos are at the bottom of the page.

You should be commended for taking this initiative - it's not necessarily an easy task, but not impossible either. The make-ready time savings on press having a blanket cut and ready to hang just like a plate will certainly justify your efforts - and hopefully be noticed/rewarded by your superiors! BE FOREWARNED, once you start cutting blankets on the table, the pressmen will conveniently forget how they used to cut blankets by hand ;) !
 

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