Cutting Aluminum

[bossfrog]

Hey gang - I am starting this thread to try to combine our Dynatorch wisdom on cutting aluminum. Of course, since I have not tried cutting aluminum yet, I have nothing to offer but questions. I plan to start cutting aluminum soon, and will post my experiences as I get into it.

Some of the previous threads had given some basic cutting voltages and speeds - please post some of these again. Also, I know there had been discussion that the edges are rough when cutting aluminum. Any solutions to this? Maybe a different gas instead of shop air?

[edwardpic]

Hey Ric,
I used Matts basic numbers from another thread and cut some 1/4 and 3/16 aluminum. I want to say 60amp tip, AV 142 and speed 65 IPM. I used the regular shop air and had great cuts. I did a sign for the inside of my shop and messed around with a couple name plates for freinds. I look forward to seeing what you come up with. Remember I use unsheilded ring with sheilded tips.

Ed

[magma-joe]

Edwardpic, here are some pictures of some .080 aluminum I cut with my dynatorch. The cuts are excellent with no dross. I keep the joystick in hand and use the feedhold feature to stop the machine between pierces to let it cool so it won't warp the material. A spray water bottle works great if needed to control the heat. The cuts I did in the picture required stopping once briefly. The only problem you have to watch for is if the material gets warped and the torch goes down for a initial height sense the material will flex down with the pressure of the torch and then raise back up causing the torch to ignite while still touching the material. To prevent this when I am doing a cut I stop the program between pierces and if neccessary lay a piece of steel for a weight in the area of the next pierce to hold the material down. I have cut .060 aluminum with success using this method. I have a 1250 hypertherm running at 84 sp , 150 inches per minute, running at 40 amps with a fine cut nozzle. I have not tried any 3/16 and thicker aluminum yet. Have you? If so what are your settings and how was the cut quality?

[edwardpic]

hey Magma,
Yes I cut some 3/16 with the settings I posted above. 60amp tip may be overkill, but never had to stop and start and cut out 6 name plates and a sign 32"x40" for my shop. Cut quality was nice and all I did was throw them in the sand blaster to get rid of the slight dross and ready for powdercoat. I have an extra sheet of 1/4" aluminum laying around and may mess with that next week. Ill be out of town on business from friday to monday.

[Edwardo]

Hi all

I know its been awhile since any posting on this thread, but i had a guy call me to cut a dragonfly out of some 1/4 alum checker plate he has. From reading your posts i should be ok with 40 amp nozzle and shop air ( i think ), going to see if he has extra plate so i can make a test cut first, we've only been cutting 1/16 steel so far with fine tips, may even give that a try also and see how it goes.

EDD

[KjZitur]

Anyone have any advice for cutting 1/2" thick aluminum?? I have the Hypertherm 1250 with 60 amp tips. I have been playing with the settings as far as set point and feed rate but I am getting more bevel than I would like to see and the tip keeps diving into the plate tripping the crash detector.........ken

[jimcolt]

KjZiter,

I would suggest referring to the Powermax1250 operators manual. The cut parameter charts are in the operation section.....look up 1/2" aluminum...and the chart will provide baseline settings as well as the correct set of consumable parts to use. These charts were developed by Hypertherm's process engineering team....and they will work. I do suggest using the speed listing for "optimal" settings as these will produce a squarer cut edge.

You do not indicate the type of machine you are using....does it have an arc voltage height control? Does it have a separate setting for pierce height? Can you set a pierce delay time? Usually...with an arc voltage height control...if the torch dives into the plate that will indicate that either 1)the arc voltage is set too low, 2) the speed is too slow, 3) the THC corner disable function is not activated, 4) the nozzle or shield may be damaged from piercing too close or inadequate peirce delay time.

There also could be an issue with plate grounding, especially with aluminum. Make sure the plate is making a good conection to the plasma system work ground cable....a poor ground will cause the THC to crash the torch.

Jim Colt

[KjZitur]

Jim, I am using a DynaTorch table with the torch height control. I have the pierce height set at 3/16, pierce delay at 1.5 and I have to have the arc voltage set to 160 (chart calls for 149)feed rate set at 30. I am using 60 amp sheilded tips with the machine set at 60 amps and 70 lbs on the air. The aluminum that I am using is a little oxidized not new and clean. How much bevel should I expect on 1/2" aluminum and should I be using a 80 amp tip? Thank you for your help Jim. I will double check all the settings today and try a few more cuts........ken

[jimcolt]

Ken,

Sounds like you are doing the right thing. The Factory voltage setting is for the maximum cut speed.....you are running at optimum speed so you have made the correct adjustment by increasing arc voltage. During steady state...straight line cutting (not cornering) adjust the arc voltage until the torch is at the recomended torch to work distance....which for the shielded parts is 1/16". It is most important to have the correct physical height than to have the correct arc voltage.

With consumables in good shape (no damage to either the nozzle or shield orifice)...you should be able to keep the cut edge angularity to 3 degrees or less on aluminum. If the torch to work distance is too high...expect the angularity to increase. If you are seeing a dramatic variation in angularity around the perimeter of the part...inspect the consumables....or watch the height caraefully to see if it may be fluctuating. Of course....you should also periodically ensure that the torch body is perpendicular to the plate....use a square , not a level.

When does the torch dive? Is it during cornering...or when cutting fine features....or has it done it on straight cuts? If the aluminum has oxidation....it may be getting a poor connection to the slats.......this will make the height incorrect...or can make the THC fluctuate. Clean a section on the edge of the plate and connect the plasma work cable directly to this area...it may help.

Aluminum is tougher to cut than steel with an air plasma system....and requires more power as the heat transfers quickly away from the cut area. You may get better results with the 80 Amp process. It is normal with air plasma to have a relatively rough, porous edge on aluminum.

Jim Colt