Fairly New to CNC Plasma Cutting,Even Newer To This Site

[GForce_Guy]

Hi everyone,

Took over on my shop's plasma cutting table back in October. I had a three day crash course with the guy who used to work it before he left and have since been on my own. Though I've come a long way, I know there is still much to learn about CNC plasma. SO far everything has come to me naturally and I have been able to figure most things out. I'm working with a Torchmate X plasma cutting table, a Hypertherm Powermax 105, and Torchmate CAD-CAM V9.

I do have one question about cutting 1/4" aluminium. I'm trying to cut a vent cover that has several slits at 1/4" wide running diagonally across the cover. The issue I'm having is the torch keeps getting caught against the metal as it is going. The charts call for a 0.06" torch-to-work distance on 45A to 85A and 0.125" for 105A. The way it looks is the shield is practically touching the metal with no space between the two and only travels a inch before the kill switch is triggered. I think it has to do with the sheet not being perfectly flat. Maybe because the sheet is slightly warped or because dross built up on the slats below on the table. I'm gonna clean the dross off the slats to see if that helps, but 0.06" seems extremely close to the metal. Is there a way I can increase the Torch-to-Work distance yet still get a clean cut? I want to run it at 45A because I read that that is preferable for aluminium.

Anyways, I'm excited to be a part of the community. Nice to meet you all!

[robertspark]

Do you have torch height control?

[GForce_Guy]

Do you have torch height control?

The control box I have has "Pierce Height" and "Init Cut Height" settings. I can also manually jog the torch up and down once it starts running the program. I know "Pierce Height" is for the start so it can penetrate the metal, so I presumed "Init Cut Height" is the same as Torch-To-Work Distance on the charts I have.

[acourtjester]

AS Robert asked do you have a Torch Height Control, the problem you talk about is why you need one. the cut height or 0.060" is very normal with a pierce height of 0.160". But this is only good at the start and should be set in the G-code for all cut starts. Then after about .5 to 1 seconds of cut time the THC come in to control the torch height by detecting the arc voltage. This also needs to be set for each metal thickness and type of metal. It then will keep the torch at the correct cutting height correcting for warps while cutting.

[GForce_Guy]

AS Robert asked do you have a Torch Height Control, the problem you talk about is why you need one. the cut height or 0.060" is very normal with a pierce height of 0.160". But this is only good at the start and should be set in the G-code for all cut starts. Then after about .5 to 1 seconds of cut time the THC come in to control the torch height by detecting the arc voltage. This also needs to be set for each metal thickness and type of metal. It then will keep the torch at the correct cutting height correcting for warps while cutting.

Oh my goodness this is what I need! Where does one usually find this feature? Is it pretty standard or is this like an add-on that I'll have to get?

Thank y'all so much for bringing this to my attention!

Edit: Okay so I was scrolling through all the settings in my control box. I noticed where it shows the current and set voltages it said manual under all that. I switched it to auto and I'm about to test it and see what happens. Is this what y'all are talking about?

[robertspark]

I switched it to auto and I'm about to test it and see what happens. Is this what y'all are talking about?

Yes..... but you will either need to enter the correct voltage.... or use a "sample and hold" strategy.....

I do not know your machine, or its controls and don't have access to your manual.....

I would suggest that maybe you need to have a word with whoever is your line manager and see if they can get you on a couple of days training course to go through everything with the manufacturer of the table.

An employer who invests in you will mean you invest in their success and productivity.... and the more metal that goes through the machine means the more you produce and the more your employer will make.... training = win win to all sides.... An employer who won't invest in you probably means they don't expect you to be around long.... not good....

[GForce_Guy]

Yes..... but you will either need to enter the correct voltage.... or use a "sample and hold" strategy.....

I do not know your machine, or its controls and don't have access to your manual.....

I would suggest that maybe you need to have a word with whoever is your line manager and see if they can get you on a couple of days training course to go through everything with the manufacturer of the table.

An employer who invests in you will mean you invest in their success and productivity.... and the more metal that goes through the machine means the more you produce and the more your employer will make.... training = win win to all sides.... An employer who won't invest in you probably means they don't expect you to be around long.... not good....

Yes I have all the parameters set according to the chart they have for 1/4" aluminium at 45A.
Voltage: 142
Cut speed: 54 ipm
Pierce delay time: 0.5"
Initial Pierce Height: 0.15" (This is what I put for "Set Pierce Height" in the control box)
Torch-to-Work Distance: 0.06" (This what I put for "Set Init Cut Height" in the control box)

I have the "Use 'Ok To Move'" option enabled and "Use Pierce Complete" option enabled. I know the "Pierce Complete" option is for the control box to control the pierce delay time. Not quite sure what the "Ok to Move" option does but I enabled it because I'm still having trouble with the torch catching the material. It has something to do with the pierce delay time, correct? I hit start, torch goes to its first spot to cut, torch goes down until it touches the material, torch goes up to the "Pierce Height", torch fires and sits there until the "Pierce Delay" has expired, torch begins to move and goes down to the "Init Cut Height". This is where it hits the metal upon barely moving out of its starting position thus activating the kill-switch. Now acourtjester said "Then after about .5 to 1 seconds of cut time the THC come in to control the torch height by detecting the arc voltage." In my original post I said it moves about an inch before hitting the metal and activating the kill-switch but in reality this happens the second it moves out of the starting position.

Taking over the plasma has reinvigorated my efforts in the shop. So far I have been able to keep up with all that they need for structural jobs which is mostly just base plates, connection plates, and stiffeners. However on the side they ask me to make a lot of custom stuff which I find the most fun because I get to use my creative side. They told me they see a lot of potential in me and growth in the company. I designed something that they really like(two return vent covers going in the sanctuary of a local church). I really hope to nail this job and impress my superiors.

Edit: Just found the sensing delay option and read what it's for. It tells the AVHC when to start adjusting for voltage. It was set at 1.4 seconds; I adjusted it down to 0.5 seconds.

[acourtjester]

From you description I would say longer on the sensing delay, the purpose for this is to allow the arc voltage to become more stable before the THC starts to control the torch movement. the "OK to move" may be what others call "arc OK" signal this signal comes from the Plasma unit stating there is current flow
Also so you know the action to touch the metal surface is called Ohmic sensing (they may call it something different) and the safety Kill switch is part of a floating head assembly to behave as it has to protect the torch from crashing or breaking. By floating head assembly I mean the torch is free to move up unrestricted a short distance and a switch which detects if it move up. You may observe this by just lifting the torch up by hand it should then trip the kill switch you spoke of.

[GForce_Guy]

From you description I would say longer on the sensing delay, the purpose for this is to allow the arc voltage to become more stable before the THC starts to control the torch movement. the "OK to move" may be what others call "arc OK" signal this signal comes from the Plasma unit stating there is current flow
Also so you know the action to touch the metal surface is called Ohmic sensing (they may call it something different) and the safety Kill switch is part of a floating head assembly to behave as it has to protect the torch from crashing or breaking. By floating head assembly I mean the torch is free to move up unrestricted a short distance and a switch which detects if it move up. You may observe this by just lifting the torch up by hand it should then trip the kill switch you spoke of.

Yeah I found out about sensing delay shortly after my last post. With THC now on auto(it has been on manual the WHOLE TIME!) its no longer catching the material. I still have some issues on take off so I think I just need to play some parameters to get just right.

I can't thank you guys enough, cheers!