Another new toy, a Laser welder

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Another new toy, a Laser welder

Postby Jerry » Sun Jun 09, 2013 1:51 am

Got another new toy on the way that I am buying from work. A 4 axis CNC laser welder!

The laser itself is a Nd:YAG made by JK Laser in England. It is rated at 55J per pulse, .5ms to 20ms pulse length, up to 100Hz pulse rep, 400W average power. The manual says it can be used for laser welding, drilling and cutting up to 5mm metal. Fun! Great for welding odd-ball metals.

Bad thing is it sucks power, at 240 3 phase it wants 66 amps peak. Ouch! The power supply is Two 19" rack cabinets bolted side by side about 4-1/2 feet tall and weighs in at about 880lbs (400kg). It also wants about 5 gal/min water cooling.

It was originally bought by Tektronix in 1985 for the display division. A friend who used to work down there said when he was there they used a ruby laser to zap tabs inside evacuated CRTs. The machine has sat for about 10-12 years now. About that time the original Anorad control died and they decided to upgrade the control to something more modern. They used MDSI OpenCNC with Yaskawa Sigma II brushless servos. After spending a LOT of money on the software, drives, and I/O the management decided this was costing too much and wanted to get out of the laser welding side of things so the project was dropped. The machine has sat ever since.

This is the software, yeah, $11,000 for the 4 axis version: http://www.mdsi2.com/Solutions/CNC_Cont ... fault.aspx

The machine has an amazing amount of documentation including copies of the original correspondence between Tek and the machine integrator, Lumonics. There are two filing cabinet drawers of complete schematics and blueprints for the laser and the machine it was integrated into. Every custom part used to put it together seems to have a print.

I am hoping I can modify it to run off of single phase. According to the schematics the power comes in and is routed to three places, a single phase transformer which supplies the DC for the control electronics, a three phase pump for the head cooling loop and two main three phase transformers in parallel. The first two are easy to deal with, a small VFD on the pump. What I am hoping is since the transformer is tapped for voltage selection I can rewire the windings for single phase operation. The output does not matter so much, it is just rectified for a 425v DC buss to charge the capacitor banks. If this does not work I have a 15HP rotary phase converter I built for my lathe that might run it.

For the cooling I will just use a garden hose for now, it wants 2 to 6 bar at 20l/min of water. If this thing does work I will probably get a plastic 55 gal drum and use a pump to circulate from that into the power supply's heat exchanger. A thermostat would add tap water to the tank as it heated to keep the temp stable. Maybe an evaporative cooler too.

It comes with an extra set of new lamps. Bad news is it sounds like it may need to have the YAG rod repolished. I cant imagine how much this is going to cost. It is a pretty good sized rod too, 3/8" diameter and 6.25" long.

Image
Lumonics laser welder by macona, on Flickr

Image
Lumonics laser welder by macona, on Flickr
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Re: Another new toy, a Laser welder

Postby Doug Coulter » Sun Jun 09, 2013 3:22 pm

Saweeeet! I have a laser head of similar specs - about 60j/pulse. When I tried to find some optics for it - say to let it into the vacuum tank for fun and games, Edmund optics said - not possible, spread the beam first.
With what? How to do that without optics? Mine's the same wavelength, also water cooled and so forth - looks like it might even be possible to use it in your machine (I'm not in love with it if you want it, I bought it for the big caps).

I'm guessing that for other than punching holes, you can't get the power requirements down much - to weld, don't you have to keep the weld hot as you progress? Else you could just cut down the pulse rep rate.
You should be able to tune down the power/pulse as well - but there are limits as you hit the lasing pump threshold.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Another new toy, a Laser welder

Postby Jerry » Mon Jun 10, 2013 12:25 am

I would love to get ahold of that head. Maybe I can make it work. Any pics?

Laser welding is quite a different process than the normal tig or mig welding. It is often done with pulses and this machine can easily do that. You can set the pulse duration and lamp current/voltage so you can really tune it down to what you want to do. It ought to be good to weld your grids. I can weld just about any metal with it. It is also good for high vacuum stuff, gets a real good weld with deep penetration with low porosity. Also has a very small heat affected zone. A couple neat videos of laser welding.



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Re: Another new toy, a Laser welder

Postby johnf » Mon Jun 10, 2013 1:21 am

Bye golly Jerry
you have all the where with all to build a laser sinterer with all that kit
either vacuum or an inert atmosphere of argon and you will have a 3D printer that is useful
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Re: Another new toy, a Laser welder

Postby Jerry » Tue Jun 11, 2013 12:36 am

Oooo, that's a good idea. I might have to try that.

I was digging through some of the documentation and found the blueprints for the demo and build out for the floor at Tektronix where this was being installed. Pretty cool! (Building 48, 3rd floor)

Here is a pic of the schematic of the power side of the power supply:

Image
Laser Welder Schematic by macona, on Flickr

This is the rectification section, three MDD42-12N1 half bridge per lamp, they are rated at 100A IFRMS and 64A IFAVM, whatever that means, forward current root mean squared and forward average mean. I couldnt find definitions. Either way they should be happy if I can figure out how to run it off of single phase by rewiring.

Image
DC Buss Rectifiers by macona, on Flickr
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Re: Another new toy, a Laser welder

Postby Jerry » Wed Jun 12, 2013 1:12 am

A little more info on it I found today, the X and Y travel is 18 and 12" and the Z is 8". It weighs way more than I anticipated, the plate that the x-y axis table is mounted to is a 4'x4'x1" thick piece of steel with a 9x5 grid of 1/2"x4" steel on edge under that. That calculates to about 1035lbs. And thats just part of the machine, the frame is made from 3" square steel tubing.

One of the things it was used for was welding on the crt end cap terminals to the wires that come out of the glass. The old ones were soldered.

In the correspondence between Tek and Lumonics I found out the price of the machine, over $270,000. Thats about $450k in todays money.
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Re: Another new toy, a Laser welder

Postby chrismb » Wed Jun 12, 2013 6:43 am

Where the heck do you get all this stuff from, Jerry? OK, you don't have to spill that particular secret, if it is a secret, but I'm always interesting in chewing over how much folks pay for their 'scores'?
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Re: Another new toy, a Laser welder

Postby Doug Coulter » Wed Jun 12, 2013 12:44 pm

I believe Jerry lives near the Tektronix junkyard...If you want scrounging tips in general, ask BillF or look what he's already put up here - he is a MASTER at that.
Anyway, here's the pix of the laser head I've got. I paid $1.5k for this, the caps, the big inductor (about 80 lbs of copper wire, air core). 1.5k joules in (at a guess from the cap rating), 60 out, at 1ms, it says. I've never fired it up, but Frank Sans says it works and will punch a hole in a quarter with one pulse. The rod appears to be about 1/8" by 3/4" or thereabouts, around 10" long or so. Light purple, you can shine a red laser pointer down the length of it.
Laser1.jpg

Laser2.jpg

Laser3.jpg

Laser4.jpg
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Another new toy, a Laser welder

Postby Jerry » Wed Jun 12, 2013 11:27 pm

Chris, I live in an area that is full of high tech companies. Tektronix is virtually walking distance from my house. The main fabs for intel are here as well as a lot of other fabs like Maxim, Triquint, and Lattice. Plus all the support companies that supply them. So there is quite a lot of stuff around the area, but it is pretty much being in the right place at the right time.

Doug, that is a neat head. Dont think it will be of much use to me. Those lamps will take a lot more voltage than I can put out, I believe.

Brought home the first part of the pile, the power supply and the spares/manuals/etc. I am renting a trailer tomorrow to pick up and bring the main unit home.

Image
IMG_6620 by macona, on Flickr

Image
IMG_6621 by macona, on Flickr
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Re: Another new toy, a Laser welder

Postby Doug Coulter » Thu Jun 13, 2013 11:08 am

The capacitors were rated 1.5kv, but I believe that's so the inductor could more-easily stretch the pulse out - when a lamp fires, it's more or less a short circuit - about 10v drop. The head has a spark coil in it to trigger the lamps, which should work as low as a few hundred volts, but I've not tested that - this thing frankly scares me. I'm not even sure which end the beam is supposed to come out of - or whether it's just an amplifier for another, smaller laser.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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