Cutting 3/4" material

[JEL DESIGNER]

I have my machine up and running. We have been trying to cut 3/4" plate, but we have issues. The first one is that the head always go done to the material during the cut and stops. We have the plate grounded to the plasma cutter, the slats in the table have a ground wire that goes to the table ground which goes to the controller and the earth ground. I was told to add more ground when I talked to tech support. I am thinking that the mill scale on the plate is causing us issues during the cut. Do I need to be using HRPO plate when I am cutting 3/4" or 1" material. We normally buy A36 HR. i need help in getting this figured out as we have a lot of parts that get cut from these 2 sizes. Any help with this would be greatly appreciated.

 

[Dnmeistr-LECS]

Dont add more ground if not needed. Both the VFC and Accumove have there own ground cable going to the table ground, table ground to the slat support, and table ground going to earth ground is all you need. If the torch is piercing the plate then mill scale is not an issue, as it has already detected ohmic. What is an issue is you are likely running with Sample Voltage turned off, this would generally need to be turned on when AVHC is set to Auto.

 

[Bo185]

Is it piercing then moving to cut height then stopping?

Sometimes on thicker material I have noticed I have to remove the slag from the pierce, which will be on the face were the torch moves. I usually pierce first stop it and move torch up and knock off slag on top then keep it cutting as the torch will usually hit it any way when it comes back around because its thick.

 

[JEL DESIGNER]

It pierces then when it starts to cut it nose dives into the material. We always have the AVHC set to auto and sample voltage on. We have tried adjusting the material thickness and it still happens. We adjusted pierce and cutting height and nothing seems to help it. We got the table to be able to cut everything we need and that includes cutting 3/4" and 1" material. That is why I am trying to see what we can do to solve this issue.

 

[Dnmeistr-LECS]

You will notice that the Set Voltage will change essentially after every pierce, that is because Sample Voltage is On and you are cutting in Auto Mode. If the Set Voltage does not change then that would indicate that it is not reading voltage, your Height Control Status will indicate the Voltage that it is reading when cutting. If the software is not reading voltage then the Set Voltage has no value to adjust to. That would be your first clue, you can change your Distance to Corner under Machine Settings to give it a longer time before it takes a snap shot of the Arc Voltage, changing the value to 1.5.

The VFC box is polarity sensitive and will only read voltage if the wires have the proper polarity.

Generally speaking cutting 3/4 material arc voltage is not needed as the material does not warp. You don't mention what settings you are using as in the amps or feedrate.

 

[JEL DESIGNER]

We are cutting at book settings for our Flexcut 125. We just slow the ipm down a little. We are currently running at 30 ipm and 105 amps. The other settings are set to the book settings. Why would we only have this issue with 3/4" material and nothing else? It seems weird that we can cut the other sizes we use(3/16", 1/4" , 3/8", and 1/2") don't have this problem. The operator told me when it pierces it is fine and then it starts the cut and takes a nose dive into the material and stops.

 

[LECS-Chad]

We are cutting at book settings for our Flexcut 125. We just slow the ipm down a little. We are currently running at 30 ipm and 105 amps. The other settings are set to the book settings. Why would we only have this issue with 3/4" material and nothing else? It seems weird that we can cut the other sizes we use(3/16", 1/4" , 3/8", and 1/2") don't have this problem. The operator told me when it pierces it is fine and then it starts the cut and takes a nose dive into the material and stops.

Two things cause this.
1. AUTO/Sample voltage is not on
2. RAW ARC VOLTAGE not being read in or reads 0/200

Verify that AUTO and SAMPLE VOLTAGE is are on.

 

[JEL DESIGNER]

We don't turn those off. We always are using those features. This table has been giving us different problems since we got it up and running. It seems we can't always use the book guidelines as the material won't cut. It seems we always have to slow our cutting down quite a bit when we do cut things. I was told that information in the books is just a starting point and we have to make adjustments from that.Sometimes we are at 3/4 or less of the book speeds to get things to cut. It just seems weird that out of everything that we have cut that the machine doesn't want to cut is only happening on the 3/4" material. I haven't cut 1" material on the machine since earlier this year and I am concerned that when I do have to cut it again I will have the issues I am having with the 3/4" material.

 

[LECS-Chad]

We don't turn those off. We always are using those features. This table has been giving us different problems since we got it up and running. It seems we can't always use the book guidelines as the material won't cut. It seems we always have to slow our cutting down quite a bit when we do cut things. I was told that information in the books is just a starting point and we have to make adjustments from that.Sometimes we are at 3/4 or less of the book speeds to get things to cut. It just seems weird that out of everything that we have cut that the machine doesn't want to cut is only happening on the 3/4" material. I haven't cut 1" material on the machine since earlier this year and I am concerned that when I do have to cut it again I will have the issues I am having with the 3/4" material.

Only numbers I use out of the book is the Pierce Height, Cut Height, and the Pierce Delay. I then run a line speed test at the range the book states to get definite numbers for the line speed. I cut 3/4 on the FC80 at about 22ipm. I would look at your VOLTAGE numbers coming in and verify that you numbers in the SET VOLTAGE. The head is crashing into the material either because the voltage/set voltage are not close or the AUTO ON and SAMPLE VOLTAGE ON.

 

[Josh Caudle]

Having this problem as well and I have a brand new unit. As far as the two issues that cause this both have been verified as working or set correctly on the HMI. Looking forward to further responses.

 

[LECS-Chad]

Try changing the AVHC to MANUAL and see if you get the same issue. I'd be interested to see a video of what the VOLTAGE is doing when this happens.

 

[Dnmeistr-LECS]

Understanding how the AVHC works is half the battle, if you have no idea what is going on then you are flying in the dark, I have explained the functions of the HMI and how the AVHC with Sample Voltage Works and how to adjust the parameters in the background such as Distance to Corner. It would make sense that at higher amperages, the voltage is more eratic and may need a longer delay to settle down, this is what Distance to Corner is for.