CNC pierce capacity increase - torch rotation?

[ASTRO_AL]

Hi guys.

As I understand it, there is essentially no difference between the components of a machine torch and manual torch for a given machine (except the housing etc). So in theory they have the same pierce capability, yet in practice the machine torch capacity is lower due to the inability to rotate the torch into the material (must pierce directly from above).

Right so far?

So my obvious question is has anyone added a torch rotation axis to their CNC plasma in order to pierce like a manual plasma and increase cut capacity accordingly?

Would this be too complex while maintaining correct torch height? (Combining with THC)

Would it be possible to add the function to most/any software? Possibly including both location and direction (clockwise / counter clockwise) to ensure you always cut into a scrap area.

Anyone have any thoughts on this, or is it just stupid?

Cheers, Al.

[jimcolt]

Al,

There are a few high end industrial cutting machine manufacturers (MG Industries, Koike Aronson, ALLtra Corp, Esab) that full rotating beveling plasma machines. These are all pretty big machines that can real time bevel to 45 degrees....they have the capability to pierce at a bevel. Generally they have industrial plasma torches that can cut at up to 1000 Amps....so straight in piercing isn't usually a big issue for them. I'm not aware of any entry level or hobbyist level machines that can tilt the torch like you say. There's no real reason why it would'nt work....although it may be cheaper and simpler to just get a bigger plasma to pierce thicker material...or do your piercing with oxy-fuel...then start on the oxyfuel pierce hole with the plasma.

Jim

[ASTRO_AL]

Hi Jim, thanks for your reply.

It won't be cheaper or simpler to upgrade my plasma, I just bought a Hypertherm Powermax 1650 (at least I've paid for it, so it had better arrive soon!), which is going to be hard to top.

Looking at the specs, the max capacity goes from 1.5" to 3/4" when switching from manual to machine torch. I just think its a waste of the machine's capacity simply for lack of rotating the torch into the cut on thicker material.

Nice to hear the idea exists. That justifies giving it further thought! The mechanics is ok, the problem (for me) is integrating it into the software / control system.

I guess the problem for pre-piercing is that you then have to ensure your pierce points in the metal line up with the CAD model. Which is doable, but it has to be easier to just throw the raw material on the bed and cut it without worrying about datums etc.

Any idea of the required range of motion (in degrees or radians) for the rotation? Start at 45 degrees from the vertical? 60? More?

Anyway, thanks for your inputs. You work for Hypertherm, right? Any spare machine torches (or parts thereof) lying around? Happy to pay shipping and a little extra! [I had to ask - I spent all my cash on the unit!].

Love to hear any other thoughts people have.

Cheers, Al.

[jimcolt]

Al,
There has really been no testing done to determine the best angles for piercing with a Powermax torch....you would just have to experiment a little. I would suggest tipping maybe 20 degrees...and also creep the x or y motion a bit. The object is to avoid the pierce blowback. Remember you now will be piercing even thicker...so it will take longer. Most people are able to pierce 1" with no problem with the 1650 torch perpendicular.....Hypertherm's ratings are conservative....our customers tend to like us better that way! There's lots of torches and systems laying around our plant....the problem....I'd have to find another job if I sent them to anyone! I've been here for 30 years...I was the 11th employee at Hypertherm....we now have close to 1000...and the employees, now called associates, own the company. It's a great place to work.

Best regards, Jim Colt

[millman52]

I used to have loads of burn outs done for me before I built a table. For my work I use mostly 3/8" thru 1" mild steel. I personally have no experience with running plasma on my table. Soon to be installed.

I tried with (3) different steel suppliers getting plasma cut parts. I found that everything 3/8" was fine. Most 1/2" was ok. Anything thicker than that had by far to much bevel & inconsistency across the cut edge for me to jig & weld into the final assemblys.

I was also being charged the same price for plasma processed parts as Ox/Fuel burned parts. So I went back to everything above 3/8" OX/Fuel process only.

I'm not saying that better results cannot be obtained on thicker material. It has left me skeptical at best.

I will find out some time in the not to distant future, how good I will be at it. The 1650 is what I have been thinking of buying. Realistically though I have no hopes of using it for what I need, at much, if anything over 1/2". Of course this is based on the above stated reasons. Plus the fact that cut speeds (or so I have been told) on plasma & oxy end up nearly the same on thicker material.

[jimcolt]

Interesting......you say the thicker the plasma cut parts you recieved....the worse the angularity was! With modern plasma technology just the opposite should be true. As you cut thicker material with an exothermic (oxygen or air) plasma...you should expect better overall angularity.

It is very common today with a 260 Amp oxygen (Hypertherm HPR260) to produce 1" thick carbon steel cuts with less than 1 degree of taper around the perimeter, and no dross. 1" cuts at 65 inches per minute with a pierce time of 1 second with this system.

I recommend to most large steel service centers that use our products that they should be using the plasma for production cutting up to at least 1".....then only switch to oxyfuel if they can cut with two or more torches simultaneously....some use as many as 12 oxyfuel torches.

The most productive shops actually operate 4 HPR260 systems simultaneously....which can move a lot of steel on and off the table over an 8 hour shift......usually keeps at least one laborer and a crane operator hopping!

My guess would be that your supplier for plasma cut parts was using some old equipment...or that they had some issues with their height control systems...or maybe their machine operators!

Jim Colt

[millman52]

Thanks for the reply Jim. In the speed comparison I should have stated I was compairing ox/fuel to the more entry level machines.

I have no idea what the company(s) are using for equipment but I'd think a steel supplier(s) that ships across at least 3 states having pretty much newer (less than 10 year old equipment) would almost be mandatory to remain in business.

Like I said. I can't speak for or control what they do. I can only speak to the, what I concidered to be, poor cut quality above 1/2" that I have receieved.

I seem to remember at least one of them had TD Merlin 15 XC or somthing like that hooked to one of their tables. So thats around 150A & possibly 15 or so years old & I'd also bet plasma/air most likely.

I have no idea if that mod. # is exact. I have no idea why it even came to mind. it was a couple years ago I was in their facility.

Neil

[jimcolt]

Your Powermax 1250 will cut 3/4" steel faster than an oxyfuel torch. I call on a lot of the major steel suppliers in the US. Quite a few of them have 15 to 20 year old plasma cnc machines. It's worth asking when you shop around for someone to cut parts to ask for an equipment list. The more progressive operations have Oxygen plasma as a minimum....and High Definition or High Performance plasma for the tightest tolerances and best edge angularity.

Todays air plasma systems can cut steel with better quality than many of the big old industrial machines that are out there!

Jim

[xjdubber]

I dont think that builing some sort of beveling device into a machine to achieve maximum pierce is going to help you much. Like Jim said the 1650 pierces 1" perpendicular, it changes consumable life a bit but it works and you get pretty straight cuts that look very nice. Edge starting would be much easier.

[ASTRO_AL]

Jim its really great to have your input on this forum. I've learned lots from reading your posts.

I hadn't realised the 1650 will pierce 1", that was my target for the cutter, so maybe the rotational axis isn't necessary. My cutter is just coming through customs now... frustratingly slowly! Glad to hear you've got lots of torches lying around! Must be nice

xjdubber - building in the rotation would close the gap between the otherwise identical hand torch pierce rating and the machine torch pierce rating, which is significant.

Thanks for all the inputs. Al.

[xjdubber]

xjdubber - building in the rotation would close the gap between the otherwise identical hand torch pierce rating and the machine torch pierce rating, which is significant.

I know what you're trying to do, and its very possible but if you want high qualilty cuts on thicker materials at low cost you would probalby be better off going with oxy-fuel. even if you shooting all that material of to the side because of a beveled start the heat of that extra long pierce time is going to affect your consumeables.

[millman52]

The problem I have found with edge starting is the severed edge allows the base sheet to move around more & accuracy of the cut part suffers greatly.

Even If I am cutting a sheet in half. I most usually will pierce somewhere near the 1st edge then cut in half. After that hand burn the small holding tab.

Sometime edge starting is a necessity but I avoid it as much as possible.