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Plasma cutting table, CNC

BadBeta

Stainless
Joined
Feb 11, 2006
Location
Northern Europe
We are thinking of getting some plate cutting equipment for aluminium and stainless steel. Thickness up to 20mm, size at least 4x8 feet (1200x2400mm) but preferably 5x10 feet (1500x3000mm). It will be used for small series production and prototype work.

Plasma seems to be the best alternative? How does it compare to say water jet cutting as far as speed, precision and running costs go?

What are good models/ brands and do anyone have a ballpark cost for a system? Any input appreciated!
 
Plasma is good up to about 3/4" for steel, past that oxy-fuel is cheaper to run.

Waterjet is slower but more accurate. But a whole lot more expensive to run. Pretty much need a dedicated building. Lots of garnet, and you need lots of power. Talking 50 HP motors on the pumps.

If you plan on doing much in the 3/4" range look at a 200 amp plasma.

Esab, Hypertherm, C&G all make good machines and power sources, well, at least in the US. I have never seen a high end European plasma power supply and the controls for the esab machine are made over here as well. The stuff over there is totally different than here.
 
Thanks for the info!

There seems to be plenty of Hypertherm plasma equipment over here, so I guess that part of the equipment is quite similar.

I do have a decent offer a small used waterjet in good condition (5x10), but apart from running costs I'm thinking that a plasma will be more reliable? Price is also certainly an issue as we will not be using this for production work - once we know exactly what we want, and there is a fair number of them, we outsource it.

What level of precision can we expect with a plasma? (Given the right gases).
 
Thanks for the info!

There seems to be plenty of Hypertherm plasma equipment over here, so I guess that part of the equipment is quite similar.

I do have a decent offer a small used waterjet in good condition (5x10), but apart from running costs I'm thinking that a plasma will be more reliable? Price is also certainly an issue as we will not be using this for production work - once we know exactly what we want, and there is a fair number of them, we outsource it.

What level of precision can we expect with a plasma? (Given the right gases).

My understanding from talking to the guys at the shops when having work cut out, was that the waterjet can make near net sized parts that require very little machining. A big problem is nozzle wear, which will cause a wider kerf and less accuracy, and one needs to pay attention to this maintenance. plasma cut adds a heat affected zone, which can be a problem both for warpage of thinner materials and hardening of some metals. Plasma also leaves a slightly diagonal unsquare cut on one side (usually the left?) because of the direction the nozzle makes the gas vortex spin.

one other advantage of water jet over plasma is that you can easily cut glass, stone and plastic, which is not possilbe with the plasma cutter. It opens up more possibilites for money making when the machine would not otherwise be running. I have even had somebody do test cuts in MDF (fiberboard that your euro cabinets are made from), but it didn't hold up well to the water. I suspect you could do some pretty awesome stuff with marine grade plywood.

I really like our hand held hypertherm machine, but I have not used any other of the more modern machines from other companies, just older models like the lincoln procut series.

-jon
 
Newer high-def plasma systems cut much better, almost laser quality. Might be worth looking in to. You would have to talk to a rep for specs though. The more current you cut with the more kerf.

Also if you get a water table that can reduce thin sheet warpage to little or nothing.
 
We've got a fair share of different water cut parts done by others. Quality seems to be quite dependant on cutting speed, which again is correlated to price. For rough parts they will run quickly and get a cut with lots of kerf and rough end surface, and for parts which require precision slow running will do the trick. So it is somewhat adaptable on the axis of speed vs quality.

We need better quality and precision than ordinary hand plasmas. Like you say I've been told that plasma has improved a lot with the years, and that machine torches and proper gases will make for a quite precise cut. But even then there are the heat related issues, which might or might not cause problems depending on the application.

I think I'll get some plasma people to send me some samples in the appropriate materials and thicknesses. If they are good I guess plasma is the way to go, otherwise a waterjet splurge might be required.
 
For the materials that you want to cut I would really go with the Hi-Definition power source or at least the new Hi Speed Plasma power source from Hypertherm. The ability to use other mixing gases and more electrode choices will help your cut quality tremendously. As far as the table goes there are a multitude of choices when it comes to manufacturers. AKS is a new one and their tables look like they are built well. We run the Plasma Automation tables called Vicons. We're happy with them. Some other shops in our are run Kioki so there are a bunch of manufacturers so be sure to talk to several of them and get the options you are looking for.
 
Sorry I didn't catch onto this post sooner! With Todays High Definition class plasma....many users are cutting with plasma on steel up to 1" and 1-1/4" at 260 Amps. 1" cuts at 65 inches per minute with Hypertherm's HPR260.....and later this year will be cutting in the range of 85 inches per minute with technology that will be introduced at the Fabtech show in Vegas in October. The pierce capacity will also be improved to allow piercing of up to 2" material...with cut speeds in the 30 ipm range.

Plasma Automation makes a good machine.....and have sold many Hypertherm HPR plasma's over the years...Koike is another good cutting machine manufacturer. If you look on the Hypertherm website you will find a list of OEM manufacturers on Industrial Grade cutting machines. Here is a link https://www.hypertherm.com/Xnet/hypr/locator/oem.jsp

Best regards, Jim Colt
 
One thing that you need to remember, which has only been slightly mentioned- to plasma cut stainless steel, and get an acceptable edge finish, you need to use a different gas- no compressed air, like you use on mild steel.
Stainless will get very hard, black, sharp dross rewelded to the material if you use compressed air on most plasma power supplies. Big pain in the neck to grind off.

But only the bigger, more expensive power supplies are set up to use dual gas, with nitrogen or argon used for stainless, and compressed air for mild.
Like the Hi-def machines being discussed.

Before I bought a plasma machine, that I wanted to cut aluminum and stainless with, I would want the manufacturer to cut samples of MY material, in the exact alloys and thicknesses I plan on using, and check that they are up to your requirements.

The smaller, cheaper machines do not do a good job on stainless, or, sometimes, aluminum. I rarely cut either in house, as I have a small C&G machine with an older Thermal Dynamics power supply. It works great on steel, but on stainless or non-ferrous, its a lot of extra cleanup, so I often send those out to be waterjet cut.

It is certainly possible to get excellent results on aluminum and stainless with plasma- but not every machine can do it, and it will cost more for equipment initially.
 
Sorry I didn't catch onto this post sooner! With Todays High Definition class plasma....many users are cutting with plasma on steel up to 1" and 1-1/4" at 260 Amps. 1" cuts at 65 inches per minute with Hypertherm's HPR260.....and later this year will be cutting in the range of 85 inches per minute with technology that will be introduced at the Fabtech show in Vegas in October. The pierce capacity will also be improved to allow piercing of up to 2" material...with cut speeds in the 30 ipm range.

Plasma Automation makes a good machine.....and have sold many Hypertherm HPR plasma's over the years...Koike is another good cutting machine manufacturer. If you look on the Hypertherm website you will find a list of OEM manufacturers on Industrial Grade cutting machines. Here is a link https://www.hypertherm.com/Xnet/hypr/locator/oem.jsp

Best regards, Jim Colt

Jim,

I understand that plasma cutters are well capable of this now, but are they cost effective compared to water-jet at those thicknesses?

-jon
 
Plasma is certainly cost effective on almost all materials vs abrasive water jets. The cost per foot of cut with plasma is a fraction of the water jet cost...and the capital equipment (purchase cost) of plasma is usually less than the waterjet process. The abrasive water jet ....although it cuts metals at very slow speeds....produces very nice cut quality and accuracy with no heat affected zone. If you need this type of quality and are willing to pay for it...then water jets are an excellent choice. Water jets can also cut almost any material, while plasma is limited to electrically conductive metals.

An abrasive water jet will cut 2" carbon steel at about 2" per minute, plasma can cut this material at 30" per minute.

Jim
 
above about .1" Abrasive water jets definately are no longer competitive in cost of cut or travel speed. I briefly was a programmer on an abrasive water jet machine and I'm a big fan. As mentioned it's large advantage is for precise work, non metallics and parts that have precise tolerances. Really water jets compliment and take over where Plasma and lasers leave off.

Another thing is that on thin gauge material you can stack cut abrasive water jet parts if tolerances aren't in the thousandths range. That's what I was doing we were stack cutting aluminum, Copper, and stainless steels 18-20 gauge stacking about 3-5 sheets at a time. At the time I remember the cost to run the machine was ~$26-30/hr including consumables. I'm not sure how abrasive recovery systems and newer technologies fare.

The bread and butter of the machines is the versatility and the fact that it is not a thermal process, you can cut everything from bread to rock.

Our machine was very profitable but we weren't cutting anything as thick as 40mm regurarily.
 
Interesting and quite specific info!

As we are mostly into prototyping and small series I don't think the cutting speeds will be the most important issue. Precison and ready made parts is a consideration though. If plasma means that I or someone else has to spend time grinding or other second operations the actual cost of running will likely be higher than water jets.

Apart from cost my major worry about water jets are maintenance and the surroundings. That the business end will but itself apart regularly can be planned for, but what can one expect as a fair life for the major parts as pumps and so on? I also visitted a water jet shop a few years ago, and that was likely one of the most grimy places I've been. My guess would be that the abrasive get more or less airborne and sticks to everything - being abrasive I certainly wouldn't want that anywhere near machine tools, hydraulics or basically anything else. So was that just the place I visitted, or is it a general grimy rule?
 
My limited experience says the suggestion above for a dedicated building is a good one. An isolated room could work depending on traffic flow. I tested a smaller abrasive waterjet for a couple weeks with a purpose-built setup and made an impressive mess.
 
Interesting and quite specific info!

As we are mostly into prototyping and small series I don't think the cutting speeds will be the most important issue. Precison and ready made parts is a consideration though. If plasma means that I or someone else has to spend time grinding or other second operations the actual cost of running will likely be higher than water jets.

Apart from cost my major worry about water jets are maintenance and the surroundings. That the business end will but itself apart regularly can be planned for, but what can one expect as a fair life for the major parts as pumps and so on? I also visitted a water jet shop a few years ago, and that was likely one of the most grimy places I've been. My guess would be that the abrasive get more or less airborne and sticks to everything - being abrasive I certainly wouldn't want that anywhere near machine tools, hydraulics or basically anything else. So was that just the place I visitted, or is it a general grimy rule?

I don't recall the abrasive becoming extremely grimy any more than say a sand blasting unit. Abrasive will get stuck to cut material especially if it has a laser guard material on one or both sides. However once the stock is dry it can be cleaned quite easily or it can be washed down when wet on the bed. The water I used was tucked in the corner of a shop about 20' from 3 horizontal milling machines. The abrasive has been known to cause problems with the lead screws on the water jet table but I don't think it presented a problem with our other machines. They can be loud too, probably similar to plasma without the light or fumes hazard.

About travel speed I misquoted myself above about .5" waterjets are no longer competitive in terms of travel speed and cost to cut. very quickly off the top of my head machine cost in terms of energy and cosumables use was approximately $30/hr This was about 5 years ago and I'm not sure if anything has changed. There are wear components like the focusing jewel and the nozzle. off the top of my head those go in the 400-1000 range. can't remember the lifetime on it, usually measured in the hundreds or thousands of hours range.

Finally in terms of maintaince the pump seals have a finite lifetime, somewhere in the thousands of hours range if i remember correctly, the high pressure lines are at 50,000-60,000+ PSI and are subject to creap, and water hammer type effects. I never did any servicing but parts like the pump seals and focusing nozzle have to be changed fairly often, but it's nothing that's overly complex. This also varies depending on the type of pump used how often the machine is cycled, it's line pressure etc.


some websites and manufacturers could probably give you a better and more accurate breakdown of operating costs, you could try talking to a machine owner to get their opinion too. In terms of secondary machining the really depends on your criteria for finish but i'd say it's superior to plasma (no dross or slag on backside) and very similar to laser without the heat affection issues.
 
I believe the shop I visitted had a lot of cutting above the water level instead of slightly submerged. Either way every surface was covered in sand. (The computers actually looked quite prehistoric à la Flintstones).

Above .5? I though they weren't competitive below that thickness?
 








 
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