Help CNC routing aluminum with applied vinyl

[jtcollins]

We have been trying to route aluminum signs with the vinyl graphic applied already to the substrate (instead of cutting the substrate and then taking it to the laminator to apply the graphic) and have had very limited success.

I am running a Multicam GraphXcutter with onsrud 63-710 upcut aluminum bit at 45 ipm xy, 40 ipm plunge, and 18,000 rpm.

Mostly the bit will start to pull up the aluminum because a burr has been welded into the bit, or the bit will pull up the vinyl and push aluminum shavings between the vinyl and the substrate which is a hassle to file down. I have had a bit fail within 8 inches of beginning the job. By fail i mean it is "pulling" up the aluminum around the edges of the bit and sometimes there isn't even a welded piece of burr to the bit. It's pretty frustrating.

We use Grimco primed .04 aluminum and naked "milled" .08 aluminum and mostly have problems with the 04 aluminum. i think it has something to do with the primed side "gumming" up the bit or because the material is "softer" than the 08 aluminum is.

Anyone out there doing this successfully and care to share?

 

[GVP]

How many passes?

 

[jtcollins]

1 pass for .04 and 2 passes for .08

 

[MikePro]

i've had success routing the aluminum w/ vinyl face-down. Helps having the bit pulling the vinyl up-towards the aluminum as it cuts, to keep the layers together.
Always making a rough pass that's not all the way through the aluminum before the final cut, to minimize the amount of heat/friction while cutting the vinyl layer.\

I also add a layer, sometimes two, of transfer mask or paint mask to protect the vinyl. Also helps with rigidity, helping it cut rather than tear.

 

[jtcollins]

The production manager told me that they used to flip the sheet and cut upside down but they stopped doing that because they would have to route out the fiducials (registration marks, bomb sights whatever you guys call them) which would add a new issue being that the camera would sometimes misread the fiducials and the cut line could shift. Has that ever happened to you? If so, how did you fix it?

Putting transfer mask on the vinyl is a new one and we will definitely try it.

 

[MikePro]

i don't use targets, as my router is just a simple xyz cnc. set home/surface/maxdepth & away I go.

if I did, however, I'm sure I could engineer a way to do it.... as I've been able to route sheets with targets that allowed me to flip & realign:
assuming you having a vinyl sheet with printed targets, applied to metal, then maybe drill a hole through the center of each target and apply a new target to the reverse-side?
or does your scanner require a white base to even register the targets in the first place? idk, I'm just shooting from the hip now without all the info I would acquire via trial/error.

on a different attack strategy, I have also "routed" vinyl face-up on aluminum by using an engraving bit to cut the vinyl layer, but not cut the aluminum, before peeling-away the excess vinyl and then finally routing the aluminum. ....but I'd bet I would have issues with my cutting lubricant sprayer causing lifting issues with the vinyl. As I've only done it this way with thicker/more rigid paint mask vinyl while engraving plaques that I wanted to keep my lettering/frame the painted/raw finish the sheet started with before painting the engraved portions...and still had issues with paint getting underneath the paintmask that would lift in spots while spraying.

 

[rossmosh]

Hit the aluminum with a steady stream of compressed air. It will clear the kerf and help keep the bit cooler. Cut down on reweld a huge amount.

Also try this style bit: http://www.onsrud.com/product/Item/m/itemDetail.html?itemId=63-602

A little bit more expensive but huge difference in quality of cut. It's not too often where I say that about bits but this one made a huge difference. Cut way better and finish quality went up a huge amount.[FONT=&quot][/FONT]

 

[player]

If the aluminum is sticking to the bit there is a problem with the aluminum or bit or feeds and speeds...

 

[SignProPlus-Alex]

Here is my feedrate for aluminum. .25 single flute. 120 ipm xy, 65 ipm z. Pass .065" Cold air gun ON.

 

[MikePro]

i don't use downcut bits, but does anyone think that'd simply be the best option for cutting aluminum with vinyl applied?
if anything, as a single pass to start the cut and then switch to an upcut for the final pass(s)?

my feeds&speeds are always spot on, but upcut bits are constantly pulling the vinyl away from the aluminum and pair that with a compressor/sprayer it has always ended with failure in the graphic before the cuts are even finished. hence my mad scientistry above

 

[Fast46]

3/16 downcut bit, 120ipm, 30,000 rpm, single pass. We do it all the time.

 

[Michaelh]

Vinyl side Down Use a New 3/16 Belin Spiral O Single Flute Upcut Bit 18000 rpm cut a bit slow (20 - 30) ipm

 

[alevit53]

Your feedrate is WAY to slow and the spindle rpm is too fast. We cut .063 and .080 with an rpm of around 16000 and a feedrate over 100.
The reason the aluminum is welding itself to the bit is too much heat buildup. As suggested, use air to cool off the bit and increasing the speed (although counter intuitive) will keep the bit cool.

 

[Derf]

With thin alum as you mentioned I would do the following.

Note: to cut vinyl applied to acrylic or alum. the vinyl must have had time to let the adhesive set up and bond. You also want a new sharp bit.

Vinyl side up - 6mm s/f down spiral bit at 240ipm @ 24k rpm
Vinyl side down - I would use a 10mm s/f acrylic polished bit (10x sharped than an Alum. bit) same feed and speed as above.

Note: these feeds and speeds are assuming you have a well balanced collet and quality bits with a minimal stick out for the depth cut.

If you can have air blowing on the part that will help.

Melting on the bit is due to improper chip load, the trick with alum. is getting the heat to evacuate in the chip leaving the part and the bit a lower temperature.

 

[X Edge Tools]

The cold air gun or at least straight compressed air is a very good idea when misting fluid is not an option. For something as thin as the .04 I would definitely use a single flute down cutter as it will keep from pulling up on the metal and vibrating it. It will also help protect the pulling up of your vinyl. For the .08 it is too thick to get away with the down spiral. I would definitely use a single flute O flute on that. I am assuming it is 3003 aluminum correct? The softer the aluminum the harder it is too cut, the slower you have to cut it, and the worse the edge quality will be. With that said, what others have said is correct, you are cutting too slow. Whenever you have "gumming" happening, that means the heat is staying with the tool and not leaving with the chip which means either your feedrate is too slow or your rpm is too high. You want the tool to move in a manor that will cut the aluminum and then throw the chip. If you are moving too slow, you are cutting the chip and then the chip is being cut again and again before it can throw it out which results in a harder working tool that will heat up and as soon as the tool is hot, metal begins to stick to it. Ideally with any kind of routing, you know you are in the right ball park when immediately after cutting you can grab and hold onto the tool without it burning your hand. It will be warm to the touch but not too warm to hold. If it is too warm to hold, either increase feed rate or decrease spindle speed.