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Greetings all. I have been looking around here for help and have found some really good info. So my journey begins. A little backstory. We manufacture hoods for commercial use (kitchens not cars lol). We recently purchased a plasma table to help take the weight off of our cnc man and machine. The ultimate goal: run this thing 8 hours a day and get consistent results while increasing our speed. I got pulled into this because of my abilities to draw in cad and have the gumption to see it through. Even though I had no experience with a plasma machine, but hey gotta start somewhere. We have had this machine for three months and I have had a lot of headaches.
Some of the Headaches:
--Clean cuts coming off consistently. We cut a variety of metals but mostly 18ga. Galvanized and Stainless Steel. The problem with this is we can't seem to get it dialed in to be consistant.
Solutions tried: Switching to Nitrogen for torch use. Using "fine" cutting consumables. Adjusting speed in material settings.
Current Setup:
--Plasma Pro II Table coupled with a Hypotherm Powermax 65 Plasma Cutter. We are using the fine cut nozzle (220930), electrode (220842), Shield (220948). Torch to material is set around .06"
--Nitrogen for air. Nitrogen is regulated to run in at 85 psi. Also we are cutting around 150ipm to 180ipm.
I really have some other issues but need to get this addressed so that I can satisfy the welding aspect of things. I still continue to have varieing cuts and sometimes extreme dross build up. This causes me issues due to the operator than having to grind and clean these edges before moving on through the production. Any kind of help would be greatly appreciated. The owner of the company is on me to get this problem straightned out but having no experience and unreal expections has made me question if I should step down and possibly lose my job. This is causing unneeded work on everyone involved including costs. Thank you in advance.
Last edited by Crzyrzr; 12-23-2011 at 12:35 PM.
Hi,
Have you registered with Hypertherm on Xnet?
For 18ga Stainless
cut height should be 0.02"
pierce height 400% or 0.08"
cut speed should be 325ipm
current set at 45A
pierce delay 0.2secs
Gas should be set at 85 to 135psi (flowing)
Are you using THC or fixed height?
Try these settings and let us know how you get on.
The material to torch was set to .06 by the gentleman that came out and did the setup. Looks like I have to change that. Just changed pierce delay to .2 for stainless. I am going to check into the pierce height. Would that be changed in the cad/cam program or the interface for the table itself?
I feel for you and I know exactly what you are going through right now. As of July I was new to running a plasma cutter. All the videos online make it look like a piece of cake. After quickly finding out otherwise I immediately had the sinking feeling in my gut that we made a very expensive mistake. It took months of playing with our unit and many dollars in tips, electrodes and steel to finally get some amount of consitency. We purchased our unit for prototype and light production work. All of our cutting is low carbon steel ranging from 16 GA thru 3/8" and we have a ShopSabre 4896 with a Thermal Dynamics A80. For anyone that is looking for a new unit I highly recommend ShopSabre. Their tech support is extremely helpful and patient and their table is very well built. If I had to do it over again I would buy a Hyper Therm plasma cutter though.
As mentioned by others, there are many factors that can affect your cut results. Plasma cutters are very touchy. If you are going from good parts to bad parts all in the same run my guess would be that your tip is either wearing out or getting damaged. This is probably my main source of poor cut. Tips can get expensive, but scrap is also expensive. Don't try and make your tip last to long. As soon as I notice an increase in cut bevel, bottom dross or a poor pierce it is time to change the tip. I also clean the tip after 100-150 pierces and most recently I am having to change both the tip and electrode after 400-500 pierces. I now program a sheet of steel (4x8 sheet with 100-200 parts) so that I have stop points to clean or change the tip.
Hang in there you will get it to work.
Hi, the pierce height can be set either in the cad/cam program or in the cut-charts on the cnc (depending on your system).Originally Posted by Crzyrzr
The pierce height is important as it allows for the "spatter" from the pierce to avoid fouling the torch.
You did'nt say whether you had THC or plate rider, if you have a plate rider you will not be able to control the pierce height and will end up with shorter consumable life.
I'll be more than happy to help you out. Getting the best quality cut with your plasma system is dependant on proper cut speed and cut height. From your post...it is clear (on the 18 ga.) that you are simply cutting way to slow for the system that you are using.....cutting too slow will produce dross, bad cut edge angularity, and warpage.
Further....using nitrogen will not improve cut quality on either stainless or on galvanized steel......go back to using clean dry compressed air. Air has approximately a 20% oxygen content which on the steel provides an exothermic boost for less dross and better edge quality.....on the stainless the oxygen reacts with the molten metal to allow better flow....decreasing dross as well.
The specifications listed in the cut charts in your Hypertherm manual will provide the best cut quality. My first suggestion is to set all of the parameters as the cut charts suggest.
For 18 gauge galvanized....you can use the fine cut consumables and use the mild steel cut charts.
Amps: 45
Cut Height: .06"
Pierce Height: .15"
Pierce delay: .2seconds
Cut speed: 325 ipm (recommended, if dross, try faster)
Your machine should have acceleration in the 30 to 40 miligee range, and your height control system must be able to maintain the .06" height during steady state cutting. If the height control on your machine has an arc voltage setting (arc voltage is proportional to height during the cut...highe voltage= higher height)....start with the voltage setting listed in the Hypertherm manual...then adjust up or down to achieve the proper cut height of .06"
Plasma cutting....with todays technology...is not a real finicky operation. It does however, have to be dialed in correctly to achieve the best performance. I have been with Hypertherm for 35 years.....doing cnc plasma cutting for most of that time...
Jim Colt Hypertherm
Ok right before our plant shutdown for christmas and new years, I made a couple of adjustments and ran some samples. Had some good results and some not so great ones. To clerify a couple of points: No there is no automated control for the height of the torch, it simply rolls along at at predetermined height. I also reset the torch to .02 from surface on stainless and sped it up, cuts came out better than what I have been seeing lately. I think the sweet spot I have found is this here:
Amps: 45
Height: .02
Pierce Time: .2
Speed: 275-315
This is for Stainless 18 gauge and should cover me all the way to 10 gauge.
For Galvanized I am going to run the following:
Amps: 45
Height: .06
Pierce Time: .4 (seeing as I cut mostly 16 ga)
Speed: 250
Hopefully this will cover as many bases as possible with little manually changeing.
Thank you for all your help. I recieved good news from the operator this morning that the cuts were coming out alot better than what they were. Then I will tackle the air issue. My question is this about that point: What is the advantage to using nitrogen over standard air? Did my biggest improvement come from the fact of them adding a regulator in line or switching to nitrogen? Keeping in mind that our stainless material comes in with a protective film on it?
Nitrogen will not improve your cut quality on thin gauge with the plasma system you are using....in fact you will probably see more bottom dross. You will see slightly longer electrode life....but it will not offset the cost of the nitrogen or the grinding that will be more necessary.
The best investment you could possibly make with your existing system would be for a full function torch height control. There is not any material flat enough for plasma....which needs to stay at the correct height within plus or minus about .010" for best cut quality and consumable life.
Jim Colt Hypertherm
That would explain a degrade in cut over long cuts then in "phases" ex. good --bad----good in one lineal cut. Hmm I will contact the company we purchased the table from and get some details on it.
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