Comexi Press.Draw mode percentage?

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Gorilla Printer
Posts: 319
Joined: Wed Oct 06, 2010 1:13 pm

Comexi Press.Draw mode percentage?

Post by Gorilla Printer »

Hi All
We have a Comexi CI Press that's about 20 years old.
We use tension mode for normal PE tubing / film.
And draw mode with kgs for non-flexible material.

There is another setting for draw mode using percentages, but none of us use it because there isn't a need.

But I'd like to learn more. We don't have a user manual, so thought I'd enquire here, since it's not critical.
And hoping to connect with someone that uses this function regularly. It doesn't necessarily need to be a Comexi press either. The more input the merrier is my view,

My question is when does one use these percentages in draw mode. How do you know what percentage to use? Is there a calculation?
The more detail, the better , please


Thank you in advance

Gorilla.
MShalna
Posts: 15
Joined: Wed May 31, 2023 8:09 am

Re: Comexi Press.Draw mode percentage?

Post by MShalna »

In my experience with draw, it's more of a trial and error process...

Set the draw percentage to a certain value - lets say 2% and look to see what the actual draw is reading (at a relatively slow speed maybe 125fpm) From there you reset the value to match the actual draw the press is using to maintain tension. Sometimes it's higher, other times it's lower, and it could be only a difference of a couple of tenths...

Anyway, that's how I've always used it on a Cerutti rotogravure press in the independently driven servo unit...

Hope this helps
Gorilla Printer
Posts: 319
Joined: Wed Oct 06, 2010 1:13 pm

Re: Comexi Press.Draw mode percentage?

Post by Gorilla Printer »

Thanks for your input MShalna
I was starting to think no one uses draw percentages.
I was considering experimenting, but prefer to hear from others with experience.

Is there a particular material you use it for. I'm thinking stiff material?
Thanks for chiming in

Gorilla
MShalna
Posts: 15
Joined: Wed May 31, 2023 8:09 am

Re: Comexi Press.Draw mode percentage?

Post by MShalna »

I have used it on a paper/poly/foil structure as well as a thin gauge polypropylene...

Same procedure for either one...
Gorilla Printer
Posts: 319
Joined: Wed Oct 06, 2010 1:13 pm

Re: Comexi Press.Draw mode percentage?

Post by Gorilla Printer »

MShalna wrote: Mon Nov 27, 2023 2:53 pm I have used it on a paper/poly/foil structure as well as a thin gauge polypropylene...

Same procedure for either one...
Nice. I was experimenting with draw (kgs) on thin flexible tubing. Was pleasantly surprised how well draw maintained an even tension. I'm going to experiment with percentage draw this week. I'm going to tell my senior printer first.
This is going to be awkward.He'll be going why, we never need to use it.

I'll just be straight up and say because I want to.I'll save it for night shift Lol

Much appreciated!
You are a gem MShalna

Gorilla
MShalna
Posts: 15
Joined: Wed May 31, 2023 8:09 am

Re: Comexi Press.Draw mode percentage?

Post by MShalna »

No problem. You'll never know if there is a better way if you don't try! Let the senior printer have that line!!
Brian
Posts: 15
Joined: Tue Sep 25, 2007 4:26 pm

Re: Comexi Press.Draw mode percentage?

Post by Brian »

We occasionally use draw on our PCMC's, especially on our driven bow rolls, but chiller roll has the option as well. For us, it's a percentage that the independently driven roll will run as opposed to the press speed. A draw of 1% means that if the press is running at 500 fpm the independent drive will run at 505 fpm.
Gorilla Printer
Posts: 319
Joined: Wed Oct 06, 2010 1:13 pm

Re: Comexi Press.Draw mode percentage?

Post by Gorilla Printer »

Brian wrote: Wed Dec 13, 2023 1:00 pm For us, it's a percentage that the independently driven roll will run as opposed to the press speed. A draw of 1% means that if the press is running at 500 fpm the independent drive will run at 505 fpm.

Something I learned today.
Thanks for the info Brian.

We only have settings from -2 to +2

Gorilla
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