improve cut quality

[islander261]

Hello

I have been cutting out mostly 14ga HR steel sheet for garden art and refrigerator magnets for about 2 years now. This has progressed from never having used a plasma torch, let alone a CNC one, to cutting about 3,000lbs this year. The table is a 4' X 4' Torchmate 2 that we bought second hand from another artist (whom I have now figured out knew less than me about metal working). The plasma unit is a Thermal Dynamics Cutmaster A-60 with an SL100 machine torch. My air source is a 27 CFM @ 175psi, 7.5hp IR with an 80 gallon tank , usual filters, refrigerated air drier and desiccant drier. The compressor and tank are outside and the filters and driers inside the shop. I have had to rebuild the X axis drive to be similar to a Torchmate 3 because it was woefully under powered for the speed required for the thin metal. Our table will now move at up to about 150ipm reliably.

Recently I have become frustrated that no matter how I vary the cutting parameters I can't seem to get clean cuts shown by others here. The first photo is a typical group of refrigerator magnets showing both top and bottom sides. The next photo is a close up of parts. The next photo shows my typical 30" X 48" sheet, I have to have these cut at the steel distributor because I have no mechanical handling and a bad back. The last photo is a torch tip after cutting one sheet of magnet cutouts, TD must love this as I buy a lot of these, I consider this a scrap tip because it is starting to cut much worse than new. I have cut very little thicker metal (>1/4") and it has turned out wonderfully with almost no dross and smooth cut using book numbers.

The torch was run using book settings: 120ipm, .14" Height, 93V, 70lbs air at torch, using a Torchmate Blue Screen ATHC, no pierce delay, 40A with 40A machine tip and no shield, about 1/4" over the water in the table for the photos. TD does not make standoff cutting consumables at lower ratings than 40A. The dross is easily removed with an angle grinder and wire cup wheel for production, most can be broken off with finger nail pressure as a test.

Now that I think the situation is adequately described can I expect to get better cuts if I switched to another brand of torch? I really don't care about routinely cutting anything heavier than 14 and 11ga. Can I get the Duramax torch that uses the Hypertherm Finecut consumables to work with my TD power supply? We do have positive cash flow with this setup, should I sell/scrap it and buy different one? I Know now that Torchmate and TD are not the top of the line small shop equipment. Thanks in advance for any advise.

John

[mike 1948]

Looking at your tip and pictures you seem to have a lot of blow back on your pierces. I see very little of that with my Cutmaster 52. I use same tips 40 amp, #8208 and pierce at about .17. I cut 14 ga. CRS at 130 ipm and it works well, not perfect, but not what you are seeing.
It looks like your are cutting to slow but I don't know anything about refrig. magnets.
Just as thought are you using all OEM consumables? I tried some Chinese knock offs ONCE and result was terrible. They where laser etched with TD logo and amperage and you could not tell them from the originals except for the packaging. I now buy only consumables that are OEM packaged.

Good Luck
Mike

[CNCCAJUN]

I would think you would have more options available to you with HYPERTHERM from a consumable standpoint & surely a lot of support. A very high number of Hypertherm users & Jim Colt . . .

I run a Hypertherm Powermax 85.

What you describe as cut quality I think could be improved.

I am a newbie & I can get 95% clean front and back on non-intricate files with FineCut consumables on my Hypertherm.

Now the really intricate arty type stuff is still kicking my butt as far as getting totally clean cuts front and back.
But they do look like your cuts.

I also have only cut hot roll which I believe is more prone to dross.

Hope that helps . . .
Steve

[islander261]

Hello

Thank you for the replies.

I think that I am using genuine TD consumables, I buy them from Torchmate and they come in OEM packaging.

The pieces shown in the photos are not large, the large fish is 9" long and the others are 6". I sometimes run at 130ipm on other files. Not much quality difference on short curvy cuts and slightly better on long straight cuts.

One issue I forgot to mention is that I have about .032" backlash in my ATHC. I compensate for this by adding this to the book values for pierce and start height. For those of you who don't have the Torchmate ATCH system back lash matters because the torch is driven into the plate until it over currents to find the plate location at the start of the cut and then backs out to set height.

I am aware that the mill scale on hot rolled steel will have an effect on cut quality. I am still learning about this stuff. I still have about 1,500lbs left from my last 4,000lbs buy from the steel distributor so I am stuck with it for a while. The other thing I have to factor in is that because I have to buy so much to get good pricing on my custom cut pieces I end up storing it for an extended period of time. I am not sure how cold rolled or pickled and oiled sheet will store. I do store it indoors in a heated shop.

John

[Brand X]

Turn the pressure up to 75 psi, always shielded nozzles for max life. More nozzle options with Thermal by the way... They have 20-30-40- 50/55 amp nozzles, shielded, and non shielded cups... Just because Thermal does not make standoff tips below 40 amps, does not mean you should not try them. By the way orifice size is the same between 20, and 30 amp tips. Last time I checked (ten years ago)

The part # 9-8245 for the torch shields for 40 amp tips
#9-8237 for the cup

You can use most aftermarket shields with good luck, and most Electrodes too. Tips, or nozzles, just do not cut it..I tend to stick with factory electrodes, but have a few aftermarket just to try them.. I will burn my cheap tips by using them in my hand torch, but not on the table..

You can tell the difference in tips by the color of them. also most will not have the little bevel on the front of the tip. The makings are a bit different too. Thermal have some more # on the bottom row of the tip. Sometime the relief/chamfer in the air ports is different too. Bright copper color is a dead give away of copies.. The factory stuff is a different alloy

If you ever step up to 3/16 give the 55 amp tips a try. They are better then the 40 amps, and 60 amps. Awesome cuts. 125 volts to start on the THC. Speed about 85 for the least bevel. ( I tend to shoot for the least bevel always) Because it's something you will fight with the one torch, unless things are set perfect.. (IMO) .1700 cutting standoff seems to get me there best.