Anyone having serious bowing issues with plastics?

[Scott Shepherd]

I've had my share of run in's with IPI plastics, but now my Rowmark is coming in the door with 1/4" bow in it.

Specifically, anything 1/8" thick. I get Rowmark ADA material that's 1/8" thick for a specific job I run all the time. It's now coming in so bowed I'm having to break the job up, put a 12" x 12" granite tile on one side while the other side runs. I'm also getting IPI 1/8" thick black with white core doing the same thing.

The 1/16" is also coming in with about 1/8" bow in it.

I called Johnson after fighting the last batch and was told "We are unaware of any issues. Call Rowmark".

So I call Rowmark and they say they are unaware of any issues, but it's being caused by humidity in the air. The protective plastic on one side keeps moisture from getting in, while the backside is unprotected, which allows for water to enter the product. That uneven distribution of humidity in the air is causing it to bow. They told me to remove the masking and let it sit flat for 24 hours.

Did that. Same bow in it. Never leaves.

I'm fighting this stuff really bad right now. Anyone having the same issues? Most all of this material is coming from Johnson Plastics Ohio branch. We've got some material coming from their Georgia branch to see if it resolves the problem.

Anyone else, or am I alone? It didn't use to be like this. EVERYTHING from Johnson used to be dead flat.

[Dave Johnson29]

The 1/16" is also coming in with about 1/8" bow in it.


More than likely the shipper. Small light objects get loaded to the top and with the sun on the roof of the trailer for hours and hours on end, the rest is as they say...

Not unusual in AZ as a lot of our stuff ships from NV and CA. Sun, sun, sun all the way.

Only way around it is to order more than you need and put it into stock to flatten out so it is ready for the next order. Living hand-to-mouth ya gotta take what ya gets. :)

Either that or buy a house brick with each shipment. :D:D

[Scott Shepherd]

I've been unable to get it to flatten out. I've sat tiles on it, while on flat tile for weeks at a time with no correction.

I'm about 2 shakes away from buying a used oven so I can heat it back up.

It's all curled the same way every time. 1/4" curl in it, long ways.

I've soaked it in water with the protective sheet off, sat that on dead flat items with tiles on top of them as well. Tried heating it, but that didn't end well. All I got was several sheets destined for the trash can.

[Mike Null]

This has been an ongoing problem, more with IPI than Rowmark. I suspect it's a process issue dealing with the differing coefficients of expansion of two materials bonded together.

Both companies have long been aware of the issue as has Johnson's. All have replaced material for me.

Don't waste your time trying to flatten it. It doesn't happen. I do the same as you and weight it down with marble or some other heavy material or I cut it to eliminate the bow.

I've tried the heat method and it's the worst of all and will likely ruin the material.

It has nothing to do with humidity.

[Martin Boekers]

Here I thought it was just me!

I have had to use double sided tape to hold it down while lasering.

It seems the last few orders of metal have been that way too almost like it was "sprung" it's a pain taping it down but that is the only way it works.
It get worse as the heat from the laser causes it to "pop" and I lose focus.

While we are on the material end the laser brass seems to be "flacking" slightly on the edges when cut. I have a new cutter, but it did it with the old one to, any sugestions?

Thanks,

Marty

[Scott Shepherd]

I wish I could tape it down. It's vector cutting small object out of the sheet, so I need the honeycomb table to do them.

One thing I'd like to encourage everyone that's having issues to do is to call your supplier and complain. When I called about 3 weeks ago, the guy I spoke with had a database of issues and he looked it up and said they had no reports since one time back several years ago and they resolved that issue.

So if we're all out there experiencing it and no one's complaining to the suppliers (and I mean formally complaining, not casually mentioning it to the sales rep), then they won't know it's a problem.

I'm expecting material from the Georgia plant today, so hopefully I'll have some good news to report.

[Ross Moshinsky]

Where are you getting your metal? I STRONGLY suggest Main Trophy. I have Marco, JDS, and PDU 15 minutes from my shop and I'm probably at one or the other 3-4 times a week. With that said, I still buy almost all of my metal from Main Trophy. The only thing I'll buy from JDS is their gold aluminum and I also buy JDS laser aluminum.

As far as plastic, I don't know if I've bought any 1/8" Rowmark recently. Again, I buy directly from the JDS warehouse so if the product isn't good, they will pick another piece for me.

[Mark Winlund]

Another thing you might consider is that when this stuff is produced, it is extruded in continuous lengths.... it is probably put up in large rolls for later cutting into sheets. I know that sheet metal is done this way. There is supposed to be a flattener that makes it all flat when cut into sheets, probably using heat and tension. I suspect that this machine is not operating properly, or you received material from closer to the core of the roll.

Just something to consider.

Mark

[Keith Outten]

All the engraving plastic I purchase has the same problems. I purchase from Johnson's Plastics at CNU exclusively, JDS won't seel products to schools.

I will report my findings to them ASAP.
.

[Dan Hintz]

Now may be a good time to upgrade that blower... give the vector table a really strong suction capability, like what your CNC machine has :)

[Ross Moshinsky]

I've thought about making a vacuum table for my engravers(something that could be with the rotary & laser). Taping down super thin plastics can be a pain. Vacuum table would solve that, but I don't think it's worth the couple hundred bucks it would cost when tape is only a few pennies.

As for the plastics, anyone ever spending too much and get New Hermes plastic? It's over priced and typically not worth the money, but if this is an issue with Rowmark stuff, New Hermes might be the answer for now.

[Mark Winlund]

As for the plastics, anyone ever spending too much and get New Hermes plastic? It's over priced and typically not worth the money, but if this is an issue with Rowmark stuff, New Hermes might be the answer for now.

New Hermes materials are outrageously over priced. Many years ago (40 or more) they used to be the only supplier of engraving material. I would rather imagine that fossilization has set in, and they are incapable of competition. Recently, I needed a bronze colored sheet to match existing material... ir was over $30 for a 12" x 24" sheet! Similar things can be said about their CNC engraving equipment... overpriced, proprietary fonts and software, and so forth. It is why you commonly see New Hermes equipment for sale in the Engraver's Journal.

Places like Johnson Plastics, Ability Plastics, and especially Main Trophy Supply eat New Hermes for lunch.

To get back to the subject, a vacuum table is really a neccessity if you are serious about making a living engraving. They are not hard to make; I have made quite a few over the years, even before the lasers came out. We made many thousands of badges using a vacuum table made with the rotary engraver and layers of engraving plastic. It worked quite well, and allowed us to cut out the badges with rounded corners with no trimming afterwards.

Don't forget that the rotary and laser machines are good general purpose tools that can make tooling as well as engrave.

Mark

[Liesl Dexheimer]

I have had some bowing problems with Rowmark as well. I usually order it from JDS or our local supplier but both shipments have had bowing issues. I've also had some problems with the actual plastic as well. I know not everything is perfect but a couple of sheets I have ordered have had flaws to the point that I couldn't use that piece of the plastic. I have noticed this particularly with the metals like eurogold or bright silver.

[Joe Pelonio]

Same problem here, with my same supplier as the last 6 years. I've overcome it by a few bits of very thin DS tape and sticking it onto a sacrificial sheet of 1/4" acrylic that was used for cutting out shapes, so there are may openings for the air to flow through.

[Mark Ross]

Now may be a good time to upgrade that blower... give the vector table a really strong suction capability, like what your CNC machine has :)

^^^This. We have a blower that is large enough that it literally sucks the material in place. Material can be bowed somewhat and we don't have issues.

[Rodne Gold]

You can make a vac table cheaply - use a piece of aluminium , 1.6mm is fine thats drilled with 1mm holes spaced about 10mm (just less than 1/2") apart.
Anodised ally is even better - it absorbs the laser beam.
You can use 5-8mm perspex too but it will have to be replaced soon as the laser cuts into it. But you can prolly make the whole thing on your laser if you use perspex - including frame,
Make a wooden frame high enough to fit a vacuum cleaners pipe or use a reducer if you want to go thinner with the whole assembly.
Make a solid bottom and use silicon to glue top and bottom to the frame - seal edges
Find a way to get the pipe into the machine , buy a cheap vaccum cleaner, hook it up and hey presto.
Block off areas you arent covering with your material with card or photo paper for inceased vacuum on your workpiece
We also use a steel sheet and badge backing magnets if something is bowed. I only use the vaccum table for very thin stock like papers , some veneers and engravable self ahesive stuff.
If you make it too big or too thin in terms of top materials , the whole table bows in the centre
Use something under the table to make it level
Use your focus probe or tool to "clock" it up - run the laser head wth the probe or tool just skimming the table and you will soon spot where to lift it.

[Richard Rumancik]

. . . Find a way to get the pipe into the machine , buy a cheap vaccum cleaner, hook it up and hey presto.
Block off areas you arent covering with your material with card or photo paper for inceased vacuum on your workpiece. . .

If anyone wants to use a vacuum cleaner for a vacuum table, just be aware that vacuum cleaners were not meant to be run with the intake blocked off 100%. The air flows over the motor keeping it cool. If you have at least some leakage, it might cool the motor enough to keep it from smoking. The closer you approach zero airflow, the more risk of overheating the motor and maybe even causing a fire.

[Scott Shepherd]

Just got my batch in from Georgia. Bowed like a banana. The call is in to Rowmark for the next step.

Vacuum table doesn't solve the problem. When you finish engraving, you still have a bowed piece of material. I can't hand someone a new item I just made that's got a 1/4" bow in it. I don't need to pull the bow out, I need to GET the bow out!

[Scott Shepherd]

Johnson called back, all their material for this item is bowed at their location as well. They said they are unable to supply me with flat material in this product.

Well, that's reassuring. At least we've traced it to being bowed on their shelf and it's not a function of the shipping process.

[Dan Hintz]

And at least they were willing to admit it... too many companies would look at the product on the shelf (just the two ends of it touching, mind you) and say "Nothing wrong here, must be you!".

[Rodne Gold]

Good point there Richard , you need to block areas till your work is flat. If the vac starts whining and straining its too much.

[Scott Shepherd]

Rowmark called back too, said they would pull some stock from their plant and check it, and they would make sure I got some flat sheets sent.

[Dan Hintz]

<chuckle> They'll be flat when they leave the factory, but when they show up, well... :-p

[Joe Pelonio]

<chuckle> They'll be flat when they leave the factory, but when they show up, well... :-p
That's true too, I ordered from them in the summertime and found it warped from sitting all day in a hot UPS truck. That's when I found a local supplier in Seattle where I can pick it up. Trouble is the last batch from them was warped too as is all their latest shipment.

[Tim Baude]

Just got 10 sheets of IPI Engravers advantage. Use for trophy plates, plaque plates etc. They are the most bowed I have ever had. I will have some bowing, but not all the time. I am going to let JDS know....it is a pain to keep it flat for the cutting with the honeycomb table. Glad that I am not the only one to experience, but wish none of us had to.
Tim

[Bill Cunningham]

I haven't had a problem with new material, but once in a while I get a job where a lot of material has to be removed, so of course, the heat makes it warp. I keep my stuff flat during engraving by using a sheet of brass coated steel on the table, and the parts held flat with some 1/4" super magnets. I never cut all the way through ordinary 1/16 laser plastic, but rather just score it with the laser, and snap them cleanly apart afterwards. If I have to flatten a piece after engraving, I have a small drying oven, used for air flow heat drying water wash hard polymer printing plates. I run this at about 45deg C with a small weight on the piece for about 30 min, then turn off the oven, and let it cool..
Comes out dead flat

[Scott Shepherd]

Material just arrived from Rowmark. Dead flat, and I mean dead flat.

It was wrapped in plastic (like a poly bag).

Very good looking material. So it's apparently leaving the factory flat and it's not getting warped in transit, at least this piece didn't.

[Joe Pelonio]

Material just arrived from Rowmark. Dead flat, and I mean dead flat.

It was wrapped in plastic (like a poly bag).

Very good looking material. So it's apparently leaving the factory flat and it's not getting warped in transit, at least this piece didn't.
I have some arriving by UPS today too, I hope it's as flat as yours.

[Scott Shepherd]

One thing to note, the material I ordered was quarter sheets, the material Rowmark sent was full sheets. So the full sheet is dead flat. I would like to know if it's flat after it's sheared. The process of shearing it could be introducing stress into the material or it could be something else completely. But it's not too many steps between the full sheet and the quarter sheet and shipping them.

[Doug Griffith]

I suspect it's a process issue dealing with the differing coefficients of expansion of two materials bonded together.

I'd bet money Mike is correct on this. I'm surprised coextruding 2 dissimilar materials ever comes out flat.

[Dan Hintz]

The shearing process only introduces localized stress (<1-2"), so that won't warp an entire sheet. Unfortunately, this doesn't disprove a manufacturing issue... since yours came directly from the factory, there is no appreciable shelf-time to allow warping to happen, which may take weeks/months. If you can afford it, leave one of the new sheets sitting on the shelf for a couple of months and see if it warps... still not definitive, but one more data point.

[Scott Shepherd]

I'd bet money Mike is correct on this. I'm surprised coextruding 2 dissimilar materials ever comes out flat.

Sorry to burst your theory, but this material is ADA material (the material that came in from Rowmark) and it's a solid color. No lamination in this process.

It's 1/8" solid color all the way through.

[Scott Shepherd]

Here's the latest on this. They provided full sheets, 24" x 48" instead of quarter sheets. I took one out of the plastic it was shipped in (actually wrapped in plastic), and sat it on the floor. It curled as well. So it came time to use it and I put it in the laser to cut it into 12" x 24" pieces (who needs a stinkin' saw?), and I cut them.

What I noticed was the way I cut them was against the "grain" sticker that's on the protective film. So the box was the opposite direction. It meant the bow was over the 24" section, and it wasn't bad. Gravity and the vacuum table held it down fine, removing the bow. However, on the pieces cut from Johnson, they are cut with the "grain" sticker. This makes the bow run across the 12" side, and it's not enough weight, plus the bow is along the 24" width, so it's longer, making the bow stronger.

Attached is an image showing the way they cut it at Johnson and they way I cut it. They way I cut it makes it work, they way they cut it screws it up. On this piece, it had no grain, so it wouldn't matter, but if grain mattered, then it would be a problem to some degree.

[Dan Hintz]

Iiiiiiinteresting. I'm assuming this is extruded, right, due to the directional grain? Looks like it is having the same issues extruded acrylic sheets have... extruding polymer chains will always have issues that require special post-processing (or proper initial processing). Maybe their roller locations need a little tweaking to pre-stress in a slightly different location.

[Scott Shepherd]

But it's dead flat when it comes out of their factory. The sheets I have remaining in the plastic are still dead flat.

It's only when exposed to the air and humidity all around (it's got 2 of those drier packs in the bag they came in), they seem to have the edges curl.

I took a piece and removed the protective liner and it's sitting on the table, dead flat. It's stayed flat since I unwrapped it.

I do believe this is a humidity issue and the fact that one side is protected, one is not, which allows for uneven exposure. In this case, I believe Rowmark when they say it's the humidity causing it.

This product doesn't have any grain in it, it's a solid color, ADA material, but the plastic protective sheet on it has "grain this direction" so they can use it on any material they make.

[Dan Hintz]

I guess I didn't understand what you were saying. How long was the sheet out in the air before you saw a noticeable curl?

[Scott Shepherd]

I didn't pay too much attention to the time, but I can say it was 24 hours or so, maybe a little less.

[Dan Hintz]

But it's dead flat when it comes out of their factory. The sheets I have remaining in the plastic are still dead flat.

It's only when exposed to the air and humidity all around (it's got 2 of those drier packs in the bag they came in), they seem to have the edges curl.

I took a piece and removed the protective liner and it's sitting on the table, dead flat. It's stayed flat since I unwrapped it.
Steve,

I have a few questions in to some guys I really trust to know what's what (long-time, hands-on engineers in the plastics manufacturing field), but I wanted to clarify your earlier statements.

You said the full sheets remain dead flat as long as they are kept in the poly bags (with dessicant) they were shipped in.

Later you said you removed the protective liner from a sheet and it's sitting on the table dead flat... is this immediately after removing the liner, or is this after it has been sitting in open air for 24 hours? I'm guessing from earlier statements it's the former, but I wanted to clarify.

So far, one guy believes it's not a humidity issue, but a residual stress issue (something I mentioned here yesterday morning, so we're both thinking along the same lines).

It's a bit unclear, but I believe you are saying the bowing is worst perpendicular to the grain direction (i.e., along the 4' side of a 4'x8' sheet), correct?