Want to build stationary 1000w laser

[dbren]

Hello,
I am hoping to set up a 1000w laser for a pipe cutoff operation. The pipe would be fed to a hard stop, then rotated for the cut. I will assemble a feed-through spindle, so the only questions I have are the laser setup. I have watched large cnc cutters, but know little about the components required. Can anyone point me in the right direction or companies that supply components?
Thanks!

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[Blackened]

What sort of pipe material? What quality finish to you expect? Wall thickness? This sounds like way overkill just to cut pipe. Is there a reason you absolutely have to have a laser perform the cutting? I have experience with industrial lasers and rotary axis cutting MS, SS, AL, pipe etc.. Maybe I can at least help you decide if a laser will work at all for your application?

[dbren]

What sort of pipe material? What quality finish to you expect? Wall thickness? This sounds like way overkill just to cut pipe. Is there a reason you absolutely have to have a laser perform the cutting? I have experience with industrial lasers and rotary axis cutting MS, SS, AL, pipe etc.. Maybe I can at least help you decide if a laser will work at all for your application?

Mild steel, 1-1/2" OD, .083" wall, part is an insert for a molded rubber part

I'm looking at laser as an alternative to cold saw. The length of cut is +/_ .007", and only needs deburr if it might cause a cut while being loaded by a worker into the blast tumbler for prep. It is a high volume part, repeat orders, 10,000+. It would be a big advantage if I can avoid deburr, and I assume it would run several times the production of a cold saw.

First concern is approximate cost of components; I'm usually pretty adept to setting up equipment and have a couple cnc machines, 4th axis, etc.

[Blackened]

I can't help with pricing. I don't know if a fibre laser could do this type of work. I'm only familiar with CO2 tube cutting so keep that in mind regarding the following.
Also bear in mind I'm an operator. Not an expert. But IMHO:-
1kw would be more than enough for thin MS provided you have O2 for assist gas.
Compressed air will not give you a burr free finish and will need a much slower feedrate. However the burr wouldn't be sharp like a cut edge. It would have some buildup of dross on the inside wall.
I don't know if 1kw would be enough power if you don't have O2. It may be a really bad idea, or it may work ok-ish. Hopefully someone else knows better than I.
You'd also need a controlled z axis to keep the gap between nozzle and tube constant. You could maybe cut without it, but quality would suffer.
1-1/2" tube wouldn't need sacrificial material down the center either. At that diameter you shouldn't get burn through of the opposite wall of the tube. Maybe a little discolouration due to heat.
Fume extraction because the iron oxide dust sucks!
If you have good edge quality, then the laser will be very repeatable re: tolerance. Obviously there are other causes of poor dimensional consistency though.
When turning lengths of tube for laser cutting, it can be a real pain if the tube isn't straight. But if you are always cutting close to the chuck then that should limit the problem.
We sometimes use a "v" shaped support where both sides of the V are rollers. So you can drag the tube through freely without having to lift it. But this can scratch the material if that's a concern. The V keep the tube approximately centred and limits side to side movement due to warped or curved tube.
You'd need consistent spindle speed.

How long are the lengths to be cut?

I hope this is of some use to you. Please tell me to shut up if I'm not being helpful lol.

[dbren]

I really appreciate any and all advice! Yes, my plans to rotate the part lean toward a lathe spindle head with air chuck. Rotation could be a fairly small variable speed drive. I can rig an easy feed system with small air cylinders, the part is less than 6" long. I've done a parts feeder for a small cnc mill and it works flawlessly.

As far as z axis, any idea what the focal length is for cutting? I think I can easily stay within .005_.010" of concentricity. I assume I could cut within a couple inches of the chuck. Is the absolute height critical for piercing?

Thanks!

[Blackened]

Your tube/part feeder sounds great.

I've used both 5" and 7.5" lenses for 2mm MS tube and you can usually get good results with either. The longer focal length iof the 7.5" is perhaps better in the sense that it helps protect the lens from spatter simply because it's further away. But it's easier to get good results with the shorter 5". Other lengths I don't know about. Also the actual focal point distance from the lens won't be exactly 5 or 7.5" from the lens. The focal point will likely be between 0 and +1mm above the surface for cutting. Once you find you're ideal standoff though you want to maintain it better than a 1mm range. Piercing focal is less critical so if you lift the nozzle for the pierce the same focus will be fine.

You should be able to pierce at the same standoff as the cut with thinner MS like this. Provided you get roughly half a bar of O2 pressure that should be enough to keep spatter from entering the nozzle. If you can at least control the power of the pierce separately that might help in dialing in a good quality pierce. You should be able to get away with the same pressure for pierce and cut too. Usually they are different values. At worst maybe you could have 2 separate manual regulators and just use an on/off solenoid on each to swap between high/low pressure. But I think you should be able to find a happy medium that works for both pierce and cut.

Higher pressures will be needed if you use air as an assist. The spatter is different and tends to damage lens' easier.

The pierce mark will be noticeable on the cut edge. It will be larger than the kerf. Tweaking pierce parameters can help reduce this effect. Pulse pierce is slower but generally cleaner and less crater effect. We usually use a leadin, but that won't be possible with a fixed laser, unless you move the entire tube, but then you also need to cut both ends of each tube.

I've thought a bit more about the tube diameter and wall thickness. You may need to put some sacrificial material down the center of the tube. It's a bit borderline. Pulse cutting can help, make sure there's no dwell after the pierce so the beam is always removing material and not going straight onto the opposite wall. But pulse cutting is slower. Even still the cut off should take a few seconds only. So there's a couple of options to reduce excessive heat in the opposite wall of the tube. Oily tube is helpful, as the oil burns off and dissipates some of the excess heat. But again, smokey.

[Blackened]

Standoff from nozzle tip to surface should also be around 1mm. Nozzle aperture maybe 1.5mm. But all these cutting variables will be slightly different between different machines.

[dbren]

Thanks for all the info!

So, it sounds necessary to have Z axis for accurate standoff.

On the pierce mark, any guess of how deep it will average?

Is there a short list of basic components for all major parts?

[cinematic2]

Thanks for all the info!

So, it sounds necessary to have Z axis for accurate standoff.

No, it`s not.
Every cutting system uses appropriate laser head that keeps "accurate standoff".
May suggest Precitec.

[Blackened]

No, it`s not.
Every cutting system uses appropriate laser head that keeps "accurate standoff".
May suggest Precitec.

And to keep "accurate standoff" the head has to rise and fall perpendicular to the work piece, be it tube or sheet. And by convention, this axis is referred to as the Z axis. But you can call it the purple axis if you like lol, the head, lens, nozzle etc must move in concert with the surface so that the nozzle standoff, and focal length remain constant with respect to the work surface. Non-metals are much less sensitive to these variables, but metals need pretty tight control for consistent quality.

You could have a pretty simple z axis though IMHO. All you'd need is a way to retract the head away from the tube to a top position, and the surface following could be accomplished with a floating head that has a foot in physical contact with the material, rather than an electronically controlled z axis with capacitive sensing (or other sensing types).

I'll take some photo's of 2mm MS pierces when I get a chance and post them so you get an idea

[Blackened]

This is a slug from flat sheet 2mm thick HRPO. There's no reason to expect a pierce on a tube to be significantly different IMHO. It's actually pretty good. The pierce is barely any bigger than the kerf. The kerf, on this machine being approx 0.4mm wide. This varies from machine to machine and with different parameters. If you pierce and cut without a lead-in you can feel the nick with your finger if you run it over the edge, but it's not really much of a hole. But again, results will vary greatly depending on your power, focus, standoff, O2 pressure and nozzle aperture. And every pierce won't be identical, there will be variation, sometimes the ejecta will splash in one direction, sometimes another. Pulse pierce usually gives the neatest smallest pierce at the cost of being a little slower but for 2mm MS the difference should be in the order of a few hundred mS.

I have zero clue about suppliers and component lists sorry dbren. Hopefully others can help you there.

edit: I swear I attached a photo to this. Photos are on another device and I can't fix it now

[dbren]

This is all very helpful, I like the idea of the manual foot.

I'll start the search for components and may have more questions later, thanks!