Flattening Shrink Tube

Could you have a roller or some sort of foot either side of the print area? It might hold the tube flat enough whilst you print it even if it reverts to being more tubular after.

Just like the foot of a sewing machine...

You could try rubber coated pinch rollers.

I can't imagine flat shrink tubing could possibly be too expensive since it makes up an insignificant, minuscule part of the overall cost of the product.

I'd say that you are lucky if that is the largest cost savings you can identify.

Just what the boss told me! Basically, our end product and price point needs to be competitive with the existing market, and the quantity of these we build, the difference between the rolls and the standard unflattened is 300% or more for this part. To you and I, yeah seems silly, but to the powers that be above my pay-grade, it is necessary.

OK, I understand now.

I think pinch rollers are a good bet, it might take more than one pass or more than one set of rollers.

Obviously heat isn't an option.

Good luck.

Have you checked other products to see if maybe you can get the cost down?

We use Brady PermaSleeve labels for our cable assemblies.

https://www.bradyid.com/en-us/category/wire-and-cable-sleeves/200050193

Perhaps you can get away from shrink tubing altogether and go with epoxy ink stamping or even laser etching?

Well I guess it depends on how much money and effort you have available....but a roller system with a heat source would seem to be the answer...

A simplification of one of these designs to the basics maybe....or just a series of rollers in the orientation of an accumulator with a cheap steamer feeding the bottom rollers...

http://www.kd-biella.com/en/

The tubing shrinks when heated.

I think enough heat to crease it would shrink it.

Well you wouldn't get it that hot, just warm enough to stretch out the kinks....and of course that would be optional depending on the environment and material....it might be enough to just spring load the rollers....He could pick up some used roller conveyors and build something....

$46..

It's worth a try.

https://www.ebay.com/itm/Used-gravity-conveyor-rollers-/122848346897

We don't know what sort of printer you have but, if you could pull the tube over a large curved surface whilst printing, that might work. Imagine draping the tube over the circumference of a large wheel with a bit of tension on it.

You may just need to find the right source. Where I last worked we got a bunch of heat-shrink tubing that came flat, which was for us a nuisance. If I were still there I would offer a trade!

I don't really understand the problem. I've bought shrink tubing in bulk, flattened on a spool cheaper than round sections. I don't really understand the problem.

Having read many comments have you thought of negative pressure on the inside of the tubing to flatten it, if possible you may be able to flatten the entire roll pass it through the printer and re roll it on another spool in continuous operation.

Thanks for the replies everyone! Sorry I've been silent, I've been out of work all week with a gnarly bug.

@ sucking out the air idea: I'm unsure how we'd be able to do this to an entire roll of tubing without cutting it into sections off the spool, which would likely be a bit counter productive. Neat idea, but not sure it's practical for my use unless you can elaborate? (I am no engineer)

@ rollers: This was my initial thought. just a matter of figuring out how to give them the pressure needed to make it actually flat and not just crease the edges a little. With the door technique described in the OP, I have to go back and forth a number of times before it stays. I have seen a number of mechanical setups of rollers similar to the pictures shared so it'd be a matter of if we can have someone internal design something similar.

@ printed labels: I will mention this to the boss. It COULD potentially work. Are these labels shrinkable too, or do you mean to adhere them after the tubing is shrunken? The surface we are using is fairly small. I will do some more looking into this, feel free to elaborate as well.

@ placing a foot on the printer: This COULD work, but the printer's only mechanism for pulling the tubing is a single rubber roller and with any extra weight or tension it slips and ruins the print / label length and we create scrap. This has been one of my biggest issues trying to design something myself. I made a simple wooden spool holder for the tubing as it comes, and even glued metal washers to the center holes so it'd glide as easy as possible, however once you get to the last half of the tubing, the diameter that it was relaxed to on the spool is half what it started and it starts making creases in itself as the printer pulls it, the creases get a slight hangup as it is printing and makes for a bad part (or tears the ribbon and requires a re-setup).