Crush Rollers for making Al Flake

[stix]

I've got access to use these lovely set of "crush rollers" [image attached] and was thinking I could make Al flake - perhaps not fine mesh flake but more like "firefly/flitter" or similar - for effects.

 

These are steel rollers that were an adjunct to a printing process. They were used to flatten the print image of secret codes underneath a rubber coating of those instant win scratch ticket thingo's. Doing so meant you couldn't feel the original slightly raised surface of the code underneath.

 

My brother who owns the rolling device has used it in the past to flatten out some duralumin to make a new ribbon for an old ribbon microphone (it has to be ultra thin). Therefore I already know it works well for that purpose. What I'm thinking is to get some cheap un-coated Al foil and fold it in half, roll flat, fold again, roll, and so on.

 

The process would be similar to how one would make puff pastry, except that instead of butter between the layers, I was thinking that to make the layers not stick together I could use a powder - perhaps boric acid - or would the powder impregnate itself into the Al and become useless?

 

The only other methods that I've heard about for making home-made Al flake is ball-milling (can be dangerous) or blending in a coffee grinder with a liquid - which is basically pointless because the Al is just being cut up, not flattened.

 

I'll be trialling the method this weekend, so any thoughts and ideas are appreciated.

 

Cheers.

 

[EDIT] Now that I think about it, it would probably be better to just fold the Al approx. ten times (an inch or so wide) with some powder inbetween, then roll and slowly increase the pressure (spring tensioners) and keep feeding it through until it falls to pieces, then break up and sieve.

Edited October 15, 2015 by stix

[otto]

I'd consider charcoal or carbon for the powder and might be inclined to tip the assembly by 90 degrees so you could re-run 1st run powder multiple times reducing (perhaps) even further.

[stix]

Good idea about using charcoal - I've also got come carbon black so that's worth a try. Yes, tipping the assembly 90deg was what I was thinking as well, therefore making it easier to capture bits that break off and put them back through.

[ORMDale]

First of all, I want that. Second, how do you turn it?

[Arthur]

For most people with a workshop and the interest, I don't see much problem making a pair of hard rollers, adjustable from .001" to more gap, so that atomised aluminium fed in at the top, could drop out below as fine flake or flitter. "Bright" usually means that it's done in a light oil, some seem to be stearate coated. Dark is different! Some dark ali has carbon in there some is naturally dark by virtue of the pulling apart of the micro particles of metal rather than the pushing together of the metal into flakes. Maybe the difference in the rate of rotation of the rollers is important.

[Col]

If the rollers rotate at equal speed you tend to create a crushing force in the nip, which can cause the material to split. With a roller speed difference its more stretching/smearing of the material.

[Arthur]

Which means that by controlling the roll speed and speed ratio, and by controlling the nip and feed rate of ingredients, several forms of aluminium should be possible from readily available "atomised"

[Col]

If its designed like a mangle, it may be enough to replace one of the gears for another with an extra tooth or two. It doesnt take much speed difference to create the wiping action. I use the same method on my glue roller so it moves fractionally slower than the paper.

Edited October 17, 2015 by Col

[stix]

First of all, I want that. Second, how do you turn it?

 

It's turned using the gear wheel on the r/h side. You can fit your hands around it. For a sense of scale, the steel rollers are approx. 100mm (4 inches) diameter.

 

The test was done and It was a difficult job to do. We both remarked that something like a car steering wheel would make the job easier. I ended up coating a piece of Al foil (8x8 inches) with charcoal then folding it in half once. Fed through the machine a few times, coated again, then folded and fed through again, and once more.

 

It got to a stage and started breaking up - from then on we just scooped it up from the tray underneath and fed it through again and again. There must have been some pieces that were over 200 layers within the thickness less than your average kitchen foil.

 

I screened it with a 20 mesh screen. Unfortunately the flakes did not divide. Theory vs reality doesn't always work out. If you could get the flakes to separate the method may be worthwhile pursuing.

 

 

If the rollers rotate at equal speed you tend to create a crushing force in the nip, which can cause the material to split. With a roller speed difference its more stretching/smearing of the material.

 

That sounds like a good idea Col. Unfortunately the device is not mine to meddle with and I'm not sure that "smearing" would help, it may just cause the layers to stick more?

 

Which means that by controlling the roll speed and speed ratio, and by controlling the nip and feed rate of ingredients, several forms of aluminium should be possible from readily available "atomised"

 

Thanks Arthur, I do have atomised 200 mesh Al. I was hoping for around 20 mesh flitter.

 

Cheers.