Cut Quality on 20 gauge material

[bretkindall]

I have been researching and experimenting for over a month now and cannot figure out why I am having such a poor cut quality with my CNC. I have a Linde ProStar Lancer Series PRS4 table. I work at a high school and this was the table the program had when I was hired. I am going to try and outline each of the problems I am having below, but my main issue is the cut quality. Hopefully somebody is more familiar with this table and can help me out. I will tell you that I am not a professional by any means, I lack a lot of the terminology and there are a lot of settings that I am unfamiliar with, therefore, I do not mess with them too much.

--Sensing PowerMax 65 This is an issue that I have sort of worked around. We cut two primary steel thicknesses in the shop, 12 gauge for fabrication projects and 20 gauge for metal art projects. I set my plasma to 65A for 12 ga and use 65A consumables. I have not had any issues with this. When I switch to 20 ga, I switch my plasma and consumables to 45A. Before I can cut, the table needs the Z-axis zeroed to the plate and it has the function where it senses the metal and then adjusts as needed to cut height. However, when I am running 45A consumables and I select the "Sense PowerMax 65" button, it drops the z-axis and will touch the metal but then keep dropping and pushes into the metal until the safety breaks trip. There is no way to change the settings to some sort of PowerMax 45, which I assume might be the problem. My work around is to manually move the z-axis until it barely touches the metal and then zero it out myself. This seems to work, but could possibly be the root cause of my last problem...
--Shaking Maybe this isn't a huge problem, but while cutting, the computer attached to the table shakes aggressively whenever the table moves directions on a cut. I haven't looked into this much, but this may also be the root cause of the next problem...
--Cut Quality I don't have any issues adjusting the parameters to make a quality cut with my 65A settings and 12 ga, however, I cannot figure out the golden ticket for 20 ga metal at 45A. I have cut an entire 4'x4' sheet making 1" circles adjusting the parameters between each circle. I can get it to cut worse, but never better. Dross is not my issue, the problem is the lead in. Wherever the lead in ends with the design, there is a very small pinhole that bleeds/cuts into the design. It does not cut smoothly whatsoever. I attached a picture on the link below for somebody to look at.

Here's a few things I have tried to resolve the problem:
1) I have adjusted the psi from 80-110 and everything in between.
2) I have adjusted the speed from 160-350.
3) I have adjusted the volts from 90-120.
4) I have adjusted the pierce height from 0.04" to 0.08".
5) I have done the above settings with and without an overburn (I cannot remember the exact size, but I adjusted it up once and below once of the recommended settings).
6) I have added a lead-out (made things significantly worse).
7) I have entirely replaced all consumables, and freshly greased zerks and tracks.

I found the best cut quality at 90psi, 220 ipm, 110V, 0.06" cut height, and no overburn or lead out (just a lead in). My best cut quality is shown in the picture below.

Maybe there is something glaringly wrong with what I am doing, and hopefully somebody can help. Like I said, I would consider myself a beginner when it comes to plasma tables, but I am fairly good at troubleshooting most problems, however I CANNOT figure this out. Any suggestions? I usually reach out to other local teachers when I need help, but nobody in my area is familiar with my brand of plasma table. We cannot do anything larger than 4'x4' which is a problem for a lot of the requests that we get so I intend to sell this table and purchase a larger one, but I cannot do that just yet.

Best Cut Quality

[WyoGreen]

On thin metal, try eliminating the lead in and pierce delay. You may also need to increase the pierce height to .015.

[bretkindall]

I have yet to try removing the lead in. I will give that a try tomorrow and let you know. Are you suggesting turning the pierce delay to 0? Thank you for the help!

[adbuch]

From your text above I assume you are using a Hyertherm Powermax 65 plasma cutter with Duramax torch. If so, then I would strongly recommend you switch to the Hypertherm FineCut consumables for cutting sheet metal 10 ga. and and thinner. The advantage of the FineCuts is narrower kerf width, less heat into the part, and less distortion - particularly on finer detailed cuts.

If you have the option in your control program, try setting your corner acceleration to 0.03 to 0.05 G. This will help to slow it down on the fine details while maintaining optimum speed on the straight portions.

FineCuts for 12 ga. and 20 ga. steel.jpg (74.66 KiB) Viewed 1636 times

FineCuts for 12 ga. and 20 ga. steel.jpg (74.66 KiB) Viewed 1636 times

Depending on the speed/acceleration capabilities of your particular table, you might need to use the settings from the Slow Speed FineCut chart.

FineCuts for 12 ga. and 20 ga. steel - slow speed.jpg (58.92 KiB) Viewed 1636 times

FineCuts for 12 ga. and 20 ga. steel - slow speed.jpg (58.92 KiB) Viewed 1636 times

As far as you pc (control computer) "shaking" - I'm not quite sure what you mean. Is it attached to the cutting table?

David

[SRdesign]

While troubleshooting I would suggest attaching a sharpie or pen to your z axis and running your table without the plasma torch on. That way you can eliminate the plasma from the equation first. Then once you know your table is mechanically sound you can focus on the plasma settings. But yes adbuch is correct, you don’t need 65 amp consumables for 12 gauge steel and fine cut consumables will cut much better on thinner materials.

[SRdesign]

As far as the sensing goes. Do you have a machine torch with the ohmic sensing retaining cap? If so then it shouldn’t matter if you switch from 65 to 45 amp consumables. As long as the wire on the retaining cap is still connected.

[weldguy]

I would go to a Finecut consumable and set the amps to 30 and follow the chart David posted above for your settings.

Don't mess with your air pressure, bring 100-110 into the back of the plasma cutter and leave the Hypertherm on automatic mode so it adjusts for you.

Do you have finecuts?