Laser cutting aluminum

[RuBert]

We have mentioned laser cutting on the community before, and I was going through my slides and found this picture of a Lasmac CAM laser cutting some aluminum for a sculpture that I later built.

You can't hardly beat it for precision and for leaving the aluminum clean and free of debris for welding. Aluminum is such a pain to weld anyway, that a clean edge saves a lot of time and makes for a stronger finish weld.

[novabelgica]

I agree. Aluminum can be a real pain to work with. A plasma cutter leaves an annoying brim that is hard to get rid of. I believe the price of laser cutters is dropping these days, so I might consider getting one if my plasma cutter dies on me. Not anytime soon though. ;)

Welding aluminum is, like you said, even worse than cutting it. I have a TIG, but it won't weld aluminum, so I had to use my MIG welder. It nearly drove me insane. It wouldn't ignite and when it did, it would stop all of a sudden and you had to cut the thread. In the end the sculpture looked like a hedge-hog. :p

[JAZ]

In the end the sculpture looked like a hedge-hog. :p
Now there's a mental picture! Congrats on your first hedgehog. Actually, perhaps the thing to do is to use the weakness of the process in your favor and design more sculptures for your "hedgehog series".

[RuBert]

That has happen to me also with a mig. The speed control/power ratio is very critical for using a mig, and it is hard to use them unless they are specifically designed for the process. Most of them need different sleeves for aluminum, and unless they have a push - pull mechanism they tend to jam often.

The spoolgun type is the least expensive welder that works well for smaller aluminum welding jobs.

The tig should be able to work, but how well depends on the model, and you really need a foot or hand variable output control of the amps.

I like using a tig, it is much slower to weld, but you have tremendous control. Maybe you could adapt yours to work, what kind is it?

[novabelgica]

I have a older Commercy CYTIG 400. It can be adapted to weld aluminum, but the price for an adaptor thingy is not much less than a brand new or maybe slightly used 'I can weld anything'-TIG.

Let me see if I remember this correctly... It all has to do with the electrical current. For most metals, you need alternating current, but for aluminum, you need a direct current... Right? Right. So you need to install something inside this TIG that converts your alternating current into a direct current and hey presto, you can weld aluminum, but you've just spent about 1.200 Euro on an 'old' TIG.

I think that's what I was told by the SAF representative. Ofcourse, he was trying to sell me a brand new TIG, the sneaky bugger. So I'm sticking to the hedgehogs for now.

By the way, JAZ, I like the way you think. :D

[fused]

One of the fabricating shops I've been around the past few years
has a CNC Cutter that uses water propelled abrasive to cut most
of their aluminum. In particular the thick stuff, claiming it gave
them a better cut. When I was there last it was being used to
cut stone and glass as well.

Also for thin aluminum one of my welding suppliers has been selling
a lot of aluminum 'brazing rods'. These rods have the ability to join,
brass, copper, and aluminum (even to each other), seams flow well,
and the joints are stronger than the base metals.

[RuBert]

Let me see if I remember this correctly... It all has to do with the electrical current. For most metals, you need alternating current, but for aluminum, you need a direct current... Right? Right. So you need to install something inside this TIG that converts your alternating current into a direct current and hey presto, you can weld aluminum, but you've just spent about 1.200 Euro on an 'old' TIG.

To weld .125 aluminum you would use about 135 amps Alternating Current, and a 3/32 electrode (in the US that is) using argon gas at about 17 cfh.

Probably what you need is the high frequency. With most TIG welding, we use 60 cycles per second with AC or DC in the US. The cycles involve the electrons going one direction and then turning around and going the opposite direction. There are 60 complete cycles per second. (with DC, there are rectifiers that essentially make the electrons go the same direction for use at the electrode holder).

So, when you TIG weld on AC, the arc has to re-initiate itself each time the electrons change direction. So, most machines used for TIG welding are equipped with a high-frequency switch. The cycles vary with the machine, but most that I have used are 100,000 cycles per second on high frequency. This essentially negates the zero-point when the elctrons change direction, making it easier to maintain an arc.

When doing DC welding on TIG, there is usually a high-frequency start switch. This gives the high-frequency for a short moment to assist in initiating the arc. It automatically kicks off once the arc is started.

Since your machine is able to do TIG and regular stick welding, you may find that there is a high-frequency switch that has three settings. It has "off", "start" and "on". Start is for the DC current with TIG, On is for using continuously with AC and off is for any other use with the machine (such as stick). On some machines, this switch is called "spark" rather than high freq.

Your machine might not have high-frequency capablity. In this case, the welders use a "scratch-start". This can be used for TIG also, but does tend to pollute the tip, so the high-frequency circuit is a nice addition.

I have seen high-frequency add-on boxes sold at tool auctions for a very low price compared to new, but finding the exact model that is compatible can be a challenge.

Hope that helps, I didn't really mean to run on so long, but maybe someone will find it interesting.

[novabelgica]

Russ, ofcourse it is interesting. It's good to see some interaction and discussion on the forum. Now if only I understood a word you were saying... :D

Just kidding.

My TIG can only do the AC welding, so we needed to buy an AC to DC convertor add-on... I think.

I don't often use the TIG and I rarely work with aluminum, so the add-on seemed too expensive for my needs at the time.

[RuBert]

Here are images of the actual files that the laser is following to cut the metal in the initial example. Each image represents a 48" X 144" sheet of aluminum.

By spending a little extra time I was able to save at least one sheet of aluminum if not more, simply by rotating and placing the pieces to maximize the use of material.

A total of five sheets of metal are needed to produce the sculpture.

The actual file used to cut the metal was a dxf, but I have used jpg image files here, so you can easily click on them and see a larger image.

[JAZ]

Looks like standard dressmaking to me! Remember, measure twice, cut once. Now I want to see the finished sculpture. No holding back.
All this discussion about CNC machines, etc. reminds me of how well connected my studio was when I first moved in. Next door was a sheet metal place that had a CNC machine with garnet impregnated water that could cut all sorts of fancy stuff. They were my steel supplier. Unfortunately, they went out of business. There's a welding supply shop across the street and right behind that is a scrap metal yard. Handy. Unfortunatley the city just bought both of those businesses so that in a year or eighteen months they'll start work developing those properties into something more aesthetic. Sigh. Next maybe the hardware store will fold.
I have an aluminum horse on my wall given to me by the sheetmetal people. It's pretty amazing what those devices can do.

[RuBert]

My wife makes various types of fabric art and art quilts, and she agrees with you Jaz. Sheet metal is a bit like fabric in some ways, just much harder to work with, and it doesn't stretch much.

Those water cutting machines are nice, too bad they went out of business. With the City buying property does that help you or will it eventually force you to relocate?

It seems to be a pattern that artists populate areas of cities that others didn't want... leading the way... then redevelopment starts and eventually forces the artists out. That is especially true if they are renting the space - so try and buy it cheap! ;)

I'll try and find a image to post of the final sculpture, I've got a slide of it but not a digital image yet. It is in front of an office building not far from my studio, so I just need to go snap another shot of it - which I should do anyway.

[JAZ]

...Those water cutting machines are nice, too bad they went out of business. With the City buying property does that help you or will it eventually force you to relocate?

It seems to be a pattern that artists populate areas of cities that others didn't want... leading the way... then redevelopment starts and eventually forces the artists out. That is especially true if they are renting the space - so try and buy it cheap! ;)
....

With this issue in mind, a group of five artists, myself included, who all have studios in Amesbury, went to an artists' survival conference in Boston a couple of years ago. Bill T. Jones was the main speaker and there were good workshops, and etc. It was a great day. Some of the primary messages were buy the building you are in, build bridges between the artists and community, and organize. So, we started the Amesbury Artists' Network to help one another find studios, connect with politicians, organize events to raise our visibility in the community, etc. Two guys and I worked so hard to organize local artists to buy one building. when that didn't work, we tried for another. The city consistently said in all of the newspaper articles that they wanted to attract artists and wanted to provide live/work studios, blah, blah. When election time came around I sent letters to all the candidates telling them that we'd distribute to our membership any info they had that related to artists' issues so that our group could vote for the right candidate. We thought we were doing pretty well when the guy who was elected was one of my former drawing students. Unfortunately, the bottom line is that the city wanted their idea of what artists' live/work space should look like, all organized by a developer more accustomed to designing condos. There were lots of meetings between artists and the city and we all learned a lot about what had been possible in other cities and how well those art spaces worked out. There was a showing of the very good documentary "Downside Up" about the development of MassMoCA in North Adams, MA. But in the end, one of the buildings is still not being developed even though the roof is about to fall in and the other is all rehabbed for "live/work spaces" too small and too expensive for any artist I know (and I know plenty). They're 1,000-1,500 sq. ft. and supposedly intended for both living and working. That's mighty tight. And pricey.
Some of the studio rents have gone up already, though not in my building yet. I've been working on my landlord right since the beginning, letting him know that this issue is a killer, and so far the rent in my building has stayed level for the past three years. He likes having artists because believe it or not we pay better than the machine shop that he had to evict before he converted the downstairs to a studio.
Anyway, no, it won't be good for me or for the rest of the artists here. In the last couple of years they have put in brick sidewalks and new lampposts and plantings everywhere downtown. Three new restaurants have gone in this year.
It's a matter of time.

[jwebb]

Cutting with "water-jet" (high pressure water carrying garnet grit) is used extensively in industry. The advantage is that it's a cold process - so there is no "heat affected zone" around the cut. The surfaces are metallographically clean. Also, garnet is basically just silica, so there is no chemical contamination.

[mysticalcu4u]

I agree. Aluminum can be a real pain to work with. A plasma cutter leaves an annoying brim that is hard to get rid of. I believe the price of laser cutters is dropping these days, so I might consider getting one if my plasma cutter dies on me. Not anytime soon though. ;)

Welding aluminum is, like you said, even worse than cutting it. I have a TIG, but it won't weld aluminum, so I had to use my MIG welder. It nearly drove me insane. It wouldn't ignite and when it did, it would stop all of a sudden and you had to cut the thread. In the end the sculpture looked like a hedge-hog. :p
why did you have a problem welding Al, the tig works well with Al. Can I possibly help?

[Graham]

I work at a laser cutting company here in Brisbane. Has anybody figured out how to clean cut ally all the time. We can get a clean cut about 90% of the time but from time to time we get an annoying dross left on the bottom of the cut items and it is driving us to drink trying to find a solution.We use a Bystar 3015 co2 laser with a 5.2k/w laser. We use either oxygen or nitrogen gas to cut. If anyone has figured out a foolproof way of getting a totally clean cut all the time we would very much appreciate any advice.We are a processing company cutting parts for a range of customers.

[Bill Harsey]

Cutting with "water-jet" (high pressure water carrying garnet grit) is used extensively in industry. The advantage is that it's a cold process - so there is no "heat affected zone" around the cut. The surfaces are metallographically clean. Also, garnet is basically just silica, so there is no chemical contamination.
Correct, and the cool thing about water jet is that it can be used to cut non-metal materials too like stone or plastics.
We use it a lot to cut production runs of very heat sensitive air hardening tool steels and titanium. If you can get your water jet person to slow down the inches per minute travel speed and get the (expensive) nozzle down close to the work, higher accuracy is possible.
Time is money when the machines running so you have to figure out how you want this to go.
Generally we can get tolerances with laser of .002 to .003 thousands of an inch "outside the line", water jet likes a tolerance more like .005 to .007 thousandths because there will be some angle in the cut when turning corners.

[Merlion]

Correct, and the cool thing about water jet is that it can be used to cut non-metal materials too like stone or plastics.


I dug out this old thread because I notice this decorative acrylic panel while I was having lunch today, see below.

It has a variety of 2D shapes cut into the plastic sheet and supported by another uncut sheet. It is illuminate at the top edge so that the profile edges are lighted up.

The idea is good, and so is the effect.

I think the shapes are cut with CNC controled abrasive water-jet, as the curves and the edges are very smooth. The smoothness cannot be achieved with jig saw machines and manual movements.

Locally, shops having this type of machine are not common, but they do exist. I think their main jobs are to cut marble sheets to form other types of decorative panels.

By the way, I think some thicker wooden jigsaw puzzles are also cut this way. See link (http://www.subcontractingtalk.com/news/kmt/kmt101.html). Compared with metals and hard plastic, wood is softer. Thus there is no need for addition injection of abrasives. Just very high pressure water jets will do.

[Bill Harsey]

Merlion,
Good post.

[Merlion]

Thanks Bill. But on second thought, such acrylic panels may also be cut on a CNC laser machine, as the edges of the cuts are so smooth. The heat from the laser may leave the material at the edge molten before it solidifies to a smooth surface. Abrasive water jets do not melt the material (except in a micro scale).

[Bill Harsey]

Interesting, I'll have to ask how that works the next time I'm in town around the laser outfit. That must smell good while it's being cut. :D

I've actually had one laser outfit decline to cut micarta (phenolic composite), something about folks being allergic to the (formaldehyde???) gasses being generated. We just 4 axis cnc router it for some shaping jobs now.

[Bill Harsey]

Laser technology is changing all the time, I had the chance a couple months ago to watch a new machine doing even more accurate work at a higher rate of speed in difficult steels than anything I've seen before.
We still use water jet for all heat sensitive materials.

Where's that guy from Estacada Oregon? I grew up near there and spent a lot of time up the Clackamas River.

[fused]

Reading back through this thread and thinking about past experiences, I've stick welded thick aluminum using additional torch heat to keep the metal warm and an AC current, messy work and expensive electrodes. Also when you TIG aluminum try a blunt tip instead of the sharp pointed tungsten you do your stainless with.

Nice acrylic divider Merlion, am I understanding you right that it is solid all the way accross and not perforated by the design anywhere? Pretty cool.

[Bill Harsey]

Fused,
your correct about the electrode shape when TIG welding aluminum.

My friend Steve Wolf, http://www.wolfpitts.com/ the aerobatic plane builder and pilot (who welds a lot of this stuff) grinds his tips flat or slightly round and then lets them form into a little ball on the end while welding aluminum.
All the fuel tanks he builds are shaped to fit into the wings and are pressure tested for leaks. I've seen him finish a fuel tank and have it pass testing on the first try many times.

edited to add: Steve and I go back a ways, there are at least three of the planes featured on his website that I've built parts for and my tools have been used on more.

[rberger54]

Wow - Thanks for the discussion on TIG welding of aluminum. I thought I was the only guy having problems. Got to go to the shop & check out the details of my TIG welder. I had thought it was DC - since the outputs are marked + and - and I have to switch polarity when I do stick welding in addition to adjustments on arc force - which is the amperage dial if I can remember.

I did try some Aluminum Brazing Rods a while back but found - at least the ones I was working with - that the brazing temperature was only 100 degrees or so below the aluminum melting temperature, & if I poured on heat to get get the blob to flow - I could melt the aluminum. I do note on line that vendors claim that there are different "gennerations" of Brazing Rods - different alloy mixes. Anyone got a name or a supplier of a Brazing Rod that works.