My Lumonics Laser Welder

[macona]

I brought home my Lumonics cnc laser welder the other weekend. What a beast. The power supply alone weighs 880lbs and the main section is just massive. The X-Y table is mounted to a 4'x4'x1" steel plate reinforced with 14 pieces of 1/2"x4" steel on edge. The rest of the frame is made from 3" square steel tubing and enclosed in 1/8" aluminum panels.

A little about the machine, It was bought in 1985 by Tektronix to weld the seams on their Micro Channel Plate CRTs like what was used in the Tek 2467 scope. They paid $270k for it.

It is a flashlamp driven YAG and runs in two modes, multimode for welding where it outputs 400 watts average, 55J per pulse, up to 200pps, and pulse lengths between .5 and 20ms. In this mode it is a pretty generic setup with a flat high reflector and a flat OC in a pretty short cavity.

The second mode is TEM00 where it averages about 120 watts at 100Hz and is used for cutting and drilling up to 5mm metal. To convert from this you remove the front optic and install the etalon OC, the HR is removed and a water cooled aperture is put in it's place. At the far end of the rail is a curved HR (10m) that doubles the length of the cavity and includes a intracavity telescope.

Lucky for me this thing came with everything. All the optics to convert between welding and drilling, spare flash lamps, thermal power meter, safety glasses, and absolutely complete manuals. There are full A3 sized schematics for every board in the machine. The manuals and documentation fill up almost two filing cabinet drawers.

The machine draws 66A at 220v three phase and I am using two bucking transformers to drop the voltage down to where it wants it, the place I am setting it up at has 240 delta. Last weekend I used a DC supply to reform the caps, it looks like they are still good. I was a little worried about that one! The power supply has a built in water heat exchanger with a thermostatic valve to regulate the temp and DI and carbon filters on the back. I ordered new DI resin and a new carbon filter and installed that this week. I picked up 50' of 6ga thhn wire to get this thing wired up today.

The whole thing is a dirty mess. I have the weld chamber pretty well cleaned out as well as about half the outside. The rail is pretty dusty too. I need to spend some time this weekend cleaning it out. I got a couple 500ml bottles of mass spec grade methanol to clean the optics. The machine has only been used as a welder so the intracavity telescope was removed and stored. I need to take that and the output beam expander apart to clean them as well, I am betting dust has gotten inside from the adjustment slots.

Once I get the laser working I will start messing around with the CNC portion. That is mostly done, I just need to finish the retrofit.

So, some pics:


Untitled by macona, on Flickr


IMG_2122 by macona, on Flickr


IMG_2148 by macona, on Flickr


IMG_2144 by macona, on Flickr

[Eidetic]

I love it!

[macona]

Got the laser up and running last week. Got the optical path cleaned and aligned. The resonator optics are pretty bad, I got to get some new ones. I also managed to score a new set of lamps on ebay for it. I am not sure how much it is putting out at this point, I dont think I can rely on the built in joulemeter.

A couple of my first victims:


IMG_2258 by macona, on Flickr

[daction]

Hi Macona,
Cool machine. I am a plumber and I am interested in the "DI" filter you speak of. Is it a water softener?
Dan

[macona]

Deionizing filter, it removes the remaining impurities in the water that might be absorbed into the water from hoses or other sources. It is often the final filter in a reverse osmosis system.

[daction]

Cool. I live in an area with hard water. I have done quite a lot of work on those.
The resin (when new) is a golden colour. When you have alot of iron in the water it goes brown.
There is a chemical that can be added when the system regenerates ,however the dosing system is mega bucks.
We just put a tea spoon of citric acid with each bag of salt.
I hope we are talking about the same system.

[krazer]

That sounds like a water softener, or so called 'ion exchange resin', which serves to remove the minerals that cause 'hard' water (calcium, magnesium) by replacing them with other minerals (sodium, sometimes potassium). This is the type of system that requires the owner to add salt on a regular basis.

For laser applications, it is required that there be virtually no minerals in the water (this is mostly because dissolved minerals make the water conductive, which is a problem for lasers which have exposed high voltage in the water cooling loop, such as this one), so a 'deionising' resin is used, which replaces all minerals with hyrogen or oxygen ions, which recombine to form pure water. Very rarely is di water used for homes, because di water is actually very corrosive (requires all pipes/fittings to be made of plastic, stainless steel, or a precious metal such as gold). In any case, these systems can also be regenerated, however the process is more complicated than just adding salt, in fact adding salt or any other minerals to a di system will just clog up the resin and force you to replace it sooner.

[macona]

Di systems and the salt systems are two different things. Standard DI filters use ion exchange resins. There are two components in a DI filter, beads that remove anions and beads that remove cations. They can be regenerated but to do that you must separate the beads and then process them. I believe you use an acid on one and and a base solution on the other. With a water softener system I believe you only use one of the resins. Even then there is a limit to how many times they can be regenerated and there is an age limit to the resin as well. Even if you dont use the resin the stuff needs to be changed out about once a year. For the laser I used a refillable cartridge for the resin.

Back to the laser, I found another OC for it and got the output to 200w average power. Had to go to the thermal block unit as my digital tops out at about 170 watts.

[krazer]

Wow, that is absolutely insane. Do you know what the input power is for that system? I never believed people when they said that these little single rod yag systems were capable of outputting hundreds of watts of average power, and this makes my little ~10mJ 50w DPSS systems seem like toys :-P

[macona]

16 to 18kw in Each lamp will run up to 6kw. Max rated power for the system is 400w avg and 55J peak. The most I have gotten is 34J per pulse. I am probably going to send the rod in for refurb this week.