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lwalker
01-26-2008, 03:21 PM
I need to make up a few instrument panels and the simplest way to get text on them (and make it look nice!) seems to be screen printing. I have a screen print kit but have never used it on aluminum. I have heard that Al doesn't take paint well but I seem to remember that if you spray the panel with adhesive, let it dry and then print acrylic on that, it holds up very well. I don't remember where I read this, but I'm sure that someone here has done something similar at some point.

I can easily test this, but I'm worried about it flaking off a few months later.

The alternative is to laser print on a transparency (back side) and then glue the transparency to the aluminum. Office Max type transparency is too glossy (looks cheap), and I don't want to spend $$$ on polycarbonate film only for 1 or 2 panels - the prices I've seen for a roll would be half as much as I'm charging for the entire project!

Any help would be welcome!

Alistair Hosie
01-26-2008, 03:37 PM
A lot of boats and caravans are made of aluminium and they paint very well , don't quite understand why they would't. I understand though that you need special car body filler for aluminium than steel.Just what I have heard Alistair

fasto
01-26-2008, 04:19 PM
I need to make up a few instrument panels and the simplest way to get text on them (and make it look nice!) seems to be screen printing.

The alternative is to laser print on a transparency (back side) and then glue the transparency to the aluminum. Office Max type transparency is too glossy (looks cheap), and I don't want to spend $$$ on polycarbonate film only for 1 or 2 panels - the prices I've seen for a roll would be half as much as I'm charging for the entire project!

Any help would be welcome!

Find a local printing shop that does vinyl truck signs. Have them print you a sheet that has all of your colors, lables, etc. on it. Stick it to the aluminum panel. Done.

All of my company's products use these vinyl labels. They hold up well. They cost $5 each. Can't be beat.

rotate
01-26-2008, 04:24 PM
If you have access to a colour laser printer or colour copier, then you can make good quality decal. Check out how it's done.

http://www.pulsarprofx.com/decalpro/Vertical/1_MENU/1c_How_It_Works/How_It_Works.html

Ries
01-26-2008, 04:49 PM
My local copy place, which admittedly is a big one, has an inkjet printer that prints right on Aluminum. 4' wide, up to something like 12 feet long.

You just take in a cd with your digital info on it, and they will do it.

Since all the new aluminum I buy has the size, mill run, and alloy ink jet printed on it, it would seem inkjet printing works just fine.

I know guys who have been silkscreening on aluminum for 30 years or more- and never heard of the spray glue thing.
With the right ink, silkscreen should be just fine on aluminum.

Evan
01-26-2008, 04:54 PM
Check this thread:

http://bbs.homeshopmachinist.net/showthread.php?t=25872&highlight=label

Paul Alciatore
01-26-2008, 05:51 PM
After rereading the thread on Evan's dials, I had a thought on getting various stocks for labels. I had to design some adheasive labels at work and needed a sheet that would work well in ink jet printers for continous production. we have worn out several printers by now. Each label was different but the size and pattern was the same. My local print shop was able to obtain several samples of printable stock for evaluation. They run into this on a daily basis and have sources for label stock from around the world. You would probably have to buy a hundred sheets or more but they can get almost anything and you can specify what you need.

nheng
01-26-2008, 06:40 PM
I've made a number of prototypes that are just about indistinguishable from actual membrane panels except for a slight reduction in contrast. I laser print in full color (or black onto a bright colored paper) onto a good quality white paper. It gets over-laid with a 7 mil thick velvet lexan with 3M 467/468 adhesive behind it. A screen printer that does overlays can make some of this up for you. I then apply double sided adhesive to the stack and stick it to the panel. These hold up to handling as well as the real thing. Be careful if you have panel mount hardware to either not tighten too much (not always an option) or cut clearance around it so the hardware bears against the panel. You can even include a clear window in the stack ... with patience :)

Paul, thanks for the reminder about Evan's Avery sticky sheets. I've been meaning to try them sometime. Den

lwalker
01-26-2008, 07:30 PM
Evan:
thanks, that sounds like exactly what I need. My only problem with the overhead transparency I have is that it's too glossy and I couldn't find a matte finish.
I notice it's been 3 months since you posted that; how are the labels holding up?

nheng:
Do you have a source for small quantites of that 7 mil Lexan? All the places I've seen online require that you buy an entire roll at $200+ Even eBay wasn't any help.

radiotexas
01-26-2008, 08:01 PM
There are many ways to skin this cat. Since I am blessed with the tools and the background for commercial art production (Adobe Illustrator on a Mac) I tend to overdo these things.

The most expensive and complex but longest lasting method is to prepare artwork and have the aluminum panels acid etched. The etcher will backfill the etched area with paint. Or they can simply fill the letters with paint. All depends if you have negative or positive artwork. Here is an example:

http://www.kk5im.com/rrimages/CTCfinalD.jpg

And a close-up of a single panel:

http://www.kk5im.com/rrimages/042005c.jpg

These panels are expensive but perhaps in your local area there might be a source. The artwork can be produced on a computer with most drawing software and given to the etcher on a CD (similar to the vinyl sign company posted above).

Another alternative, much cheaper, is to create the artwork with white letters on a solid black background. Print this on photo paper and laminate it TO THE BACK of clear polycarbonate (Lexan/Plexiglass etc). Then center punch and drill holes for the components. There are spray adhesives available for this purpose.

Just about any self-adhesive material you apply to a metal surface that comes into physical contact with your hand (a switch or lever on a control panel) will eventually wear. Applied to the back of the clear panel, this problem is greatly reduced.

We have also done some panels with rear illumination using transparent film for the artwork and back mounted to translucent (white) Plex.

Screen printing is pretty hard to do WELL unless you have the right equipment and experience. It still requires artwork and usually a film negative.

The link to the Avery post was pretty cool by the way. Thanks!

Evan
01-26-2008, 08:58 PM
The labels are holding up pretty well, especially the printing. I would suggest for use in a machining environment that it would be a good idea to mask and paint the exposed edges with clear nail polish. This will seal them and prevent lifting eventually. For masking tape I always use black electrical tape.

nheng
01-26-2008, 09:41 PM
lwalker, A local screen printing shop that did tee-shirts and electronic overlays (different areas of the shop :) ) made up sheets of the lexan and adhesive for me.

The lexan or its polyester equivalent (in appearance, at least) are common for such an operation but a quick glance online says they're not that easy to find. 3" x 60yd of 468 MP is about $40, $80 for twice the width. Other adhesive sheets can also work but they must be clear.

oops, found some 8A35 polycarb sheet ...

This place shows GE 8A35 0.010" velvet/polish sheet for $6.55 for 24" x 48". Sounds cheap but I've never bought any myself.

http://www.eplastics.com/Plastic/Film_Thin_Sheets/AF-0102448-PC815

PM me if you'd like a 4" x 6" sheet with adhesive applied to play with.

lazlo
01-26-2008, 11:04 PM
My local copy place, which admittedly is a big one, has an inkjet printer that prints right on Aluminum. 4' wide, up to something like 12 feet long.


Ries, that's pretty cool. Do they provide the aluminum? If not, is there a specific gauge of aluminum that you need to supply, or is the printer a flat-bed of some sort?

Can they do color too?

mechanicalmagic
01-27-2008, 12:58 AM
Depending on the application, another way is heat transfer.

A laser printer image is placed on a VERY clean part. Heated and pressed. The plastic toner bonds to the clean metal, and the original paper is removed.

I have done this many times for printed circuit boards, or simple markings. The paper is crucial to a good end product.
Dave

Mcgyver
01-27-2008, 01:11 AM
lots of good ideas, a really simple one is the toner transfer method used as a circuit board etching resist. Print using a laser printer (as to be laser) onto glossy photo paper and iron onto the panel. what you print has to be a mirror image - soak in water after ironing and fingernail off the paper. the toner is stuck onto the metal and is fairly durable.

Dave, you beat me to it :D

PaulF
01-27-2008, 01:19 AM
Hi,
I'm an electrical engineer (don't hold that against me).
When we make instruments we have panels made at a place in Seattle.
They even have a neat cad program on their web site so you can put all the text and numbers and they punch all the holes, silk screen the logo and text...the whole 9 yards.

Most large cities have these services for the electronics industry.

PaulF

Your Old Dog
01-27-2008, 08:53 AM
(on painting aluminum. When they paint boats they make it crystal clear the aluminum has to be washed in a mild acid solution that etches the surface before paint. They sell it in marina boat supply houses.)

Evan
01-27-2008, 09:46 AM
It's a chromic acid etch called Alodyne.

http://www.bd-4.org/etching.html

lwalker
01-27-2008, 12:06 PM
Dave,
I thought of this since I have the blue Pulsar toner transfer sheets, but I have never had good luck with them, no matter how scrupulously clean the copper was, it just wouldn't adhere well, or there would be dropouts. But it is worth a try since I may have better luck with aluminum and it would be a quick test.



Depending on the application, another way is heat transfer.

A laser printer image is placed on a VERY clean part. Heated and pressed. The plastic toner bonds to the clean metal, and the original paper is removed.

I have done this many times for printed circuit boards, or simple markings. The paper is crucial to a good end product.
Dave

Mad Scientist
01-27-2008, 02:27 PM
Dave,
I thought of this since I have the blue Pulsar toner transfer sheets, but I have never had good luck with them, no matter how scrupulously clean the copper was, it just wouldn't adhere well, or there would be dropouts. But it is worth a try since I may have better luck with aluminum and it would be a quick test.

Have had similar problems. Found that his helps and has given good results.
Place PCB on aluminum plate, maybe 3/16” thk. Place transfer material on PCB. Place 4-6 layers of paper towel on transfer material. Place second aluminum place on top of that and clamp together with “C” clamps. Use moderate pressure. Cook in oven at 250 degrees for about 20-30 minutes. Let cool then remove the transfer material by lifting corner and rolling back over itself.

P.S.
you still need to scrupulously clean the copper!

nheng
01-27-2008, 03:45 PM
I've had good luck with the blue PNP sheets but the copper definitely has to have "teeth".

Scrub the copper (or other metal if you're labeling with it) with an old toothbrush and Comet or other abrasive cleanser. Rinse with clean water, wipe the water off with a paper towel and never touch it again ! I put about 20 sheets of old letter paper on a flat surface, under the pcb and one sheet on top of the blue sheet. Press with a hot iron (highest setting) without moving for about 10 - 20 seconds, then move to a few different orientations (probably helps to make it "hit" all areas).

Do not move the iron while applying more than light pressure as you may smear or distort the heated toner below.

Cool under running water before peeling away the sheet. The last board I did was about a month ago and had 4 or 5 tiny SSOP packages on it. Not perfect but had 98% continuity :) before touchup.

This would probably not work on any thicker material (1 oz. pcb is 1.4 mils thick) without a preheat or baking as mentioned.

mr coffee
01-30-2008, 02:01 PM
I've spent a lot of time trying to get PnP blue to work well on both copper clad and Aluminum panels.

I highly recommend three other things I've found helpful.

1) AFTER you clean with Comet or whatever and rinse, go over the board\panel with Scotchbrite and wipe the panel off with plain white paper towel before applying the PnP. If you have a ceramic cooktop on the stove, it seems to make an idea base to do the ironing on.

2) After you peel the backing and have a successful transfer of the pattern to the panel, iron a second BLANK piece of PnP Blue onto the toner image on the panel. Then (of course) peel the second backing off and etch. This seems to make a thicker resist that allows etching 2 oz + copper clad and put deeper images in Aluminum.

3) Don't plunge aluminum into the etchant. Apply the etchant with a soft paint brush and rinse and check frequently. It will take 10 minutes instead of 10 seconds, but the detail will be a lot better. The violent etching by immersion takes some of the PnP off with it if you plunge it into etchant.

lwalker
01-30-2008, 02:53 PM
Interesting.
I usually clean the copper with degreaser and rinse well since I thought that it was oils, etc that was causing poor adhesion. I'll try going over it with fine sandpaper to give it a better surface; in fact I have an LED power flasher board I'd like to test it with.

I would love to try etching aluminum: what kind of etchant do you use? I have ferric chloride, but a friend has some ammonium (?) persulfate he wants me to take off his hands also.

Evan
01-30-2008, 05:10 PM
This is something with which I am familiar. Toner transfer sheet were developed a long time ago shortly after the Xerox Standard Camera was developed and sold. It predates the first real copier and is a large format studio camera that uses selenium plates and the xerographic process to develop an image.

The problem now is that in the 1980s certain patents on magnetic roll development held by Burroughs expired. Xerox immediately took advantage of this and began switching over to mag roll development systems. This requires that the toner be magnetic and so it is compounded with ferrite powder. This magnetic toner doesn't work worth squat compared to the non magnetic toner in the pcb transfer process.

This is easy to test. Print a small patch of solid black on a piece of ordinary paper and cut it out. See if it is attracted to a super magnet. If so, and there will be no doubt, then you need to find a machine that doesn't use magnetic toner. They still exist as not every manufacturer jumped on that bandwagon or for every model. It does have some disadvantages. Another thing to try is a color laser and print the image in solid magenta toner only. It can't be compounded to be magnetic unless they have made some recent discovery I haven't heard about.

To etch aluminum use a weak lye solution.

Mad Scientist
01-30-2008, 06:06 PM
I started out using PnP’s paper backed product and quickly decided that it was an exercise in frustration. Then switched to their mylar product, after much experimenting I am able to get it to work reasonable well. As already mentioned the board must be spotlessly clean and have a slightly roughed up surface. I use steel wool followed by an alcohol wash.

Don’t have a laser printer so I use a copier to put the image on the film. Copier is set to its darkest position to put the maximum amount of toner onto the film. (It’s the “plastic” toner that is the acid resist material. Hence the more the better.) Try to avoid touching the printed image, don’t want oily finger prints here.

Next is the tricky part, transferring the image to your metal/pcb. The goal here is to apply enough heat and pressure to re-melt the toner so it will stick. Too much heat and pressure and the image will mush out and become fatter. :o Not enough heat or pressure and it will not stick. :mad: 250 degree heat is not too hard to obtain but the correct pressure is trial and error. :(


2) After you peel the backing and have a successful transfer of the pattern to the panel, iron a second BLANK piece of PnP Blue onto the toner image on the panel. Then (of course) peel the second backing off and etch.
I have not tried this and not sure how it would help. Perhaps the reheating will cause the toner to stick better.

I would love to try etching aluminum:
Many years ago my mother made etched aluminum trays by hand painting a design on them with asphalt paint then etching them with muriatic acid. The acid would not bother the paint put it was easily washed off with turpentine. The toner being plastic should also be able to resist the acid. But I think I would want to start of with a diluted mixture.