Finding Distortion factor for coating blankets
I work for a vendor in canada (not here to sell product i promise!just here to ask for some advice and guidance.)
We recently purchased a CAD table to convert printing blankets, however I have been approached by a couple of customers and asked if we could cut spot coating blankets for them. I have run several test samples just to figure out what we could do in terms of detail and it turned out very well. Unfortunately I have not cut Spot AQ/UV blankets to go on press as of yet.
My question is...
How do I figure out the distortion factor? Also, does using a Mylar backed blanket eliminate the distortion factor?
Thanks in advance for your help, and please do not mistake this post as a way to sell products/services...
Mylar backed blankets won't necessarily eliminate the distortion. The value you're looking for is what percentage the coating blanket increases the circumference of the coating cylinder. Maybe something as simple as:
a = length of the blanket
b = blanket thickness
C = circumference of cylinder with blanket
D = diameter of the cylinder
D2 = diameter of the cylinder and blanket
a ÷ pi = D
D + (2b) = D2
D2 x pi = C
a ÷ C = distortion factor
Thanks for the info, I will give that a shot and let you know how it worked!
This is great info, we were looking for this as well!
Originally Posted by rich apollo
Looking at this formula theoretically you could change the values a little bit and use it to find distortion percentage when perfing on press. We do some fairly intricate perfs and usually it takes a few tries to get the perf rules to line up.
It's very hard to do a spot coat on a coater blanket while it's off the cylinder(actually that part is easy,it's when you remount the blanket,that's where the trouble begins).You can do ok with glue flaps,large areas but if you want to get really fancy(knockouts ect) you have to cut the blanket or plate while it's mounted on the cylinder and even then you have to be very careful.
Originally Posted by Anthony Hyatali
I tried it out using this distortion factor and it worked out rather well! I can't really see a problem with it if i'm using coating plates or mylar backed coating blankets.
Rich, thanks for the information, it was extremely helpful!
Thanks for the feedback, Anthony. I was kinda' guessing.
Originally Posted by peter61
My old shop used cyrel polymer coating blankets and they were great as long as some muscle-bound operator didn't over-tighten them. My new shop cuts 4-ply blankets on a special machine and they never fit right. And the misregistration from bearer to bearer is worse than from gripper to tail.
is it possible that they have not found the proper distortion factor? Or perhaps there is just way too much stretch in the 4 ply blanket?
There are macinhes on the market that will cut coating plates, i figure it's the same idea right? the only difference is that I will be cutting on a falt bed table instead of a cylinder with tractor feed (gerber sector)