Hypertherm PowerMax1000 and Water Table won't work?

[barnon]

I was told by a technical rep from Hypertherm that beacuse of the way they start the arc that a water table would short out the arc.

Can anybody here prove him wrong?

[mcnerney]

Barnon

I have never tried under water cutting, I know there are several folks that use a water table and adjust the metal so that it just sits on top of the water. This will reduce the warpage on thinner materials and help disapate the smoke. Here is a portion of a reply (on this subject) that was posted on the plasmacutting forum on Yahoo a few days ago.

As I tried to state before…the non-high frequency air plasma torches as used on the Hypertherm Powermax systems can be used over a water table….but are not designed to be submerged. There are some users operating Powermax systems with the torch submerged…..and I understand that they seem to work well…..but the torch is not recommended to be used this way by Hypertherm. Some users do underwater cutting at their own risk.

[xt300301nut]

During the find height mode of operation there is no air flowing throufgh the torch body. Thus once the torch head moves under water it fills with "dirty" water. When the CNC sends a start signal to the Power source the power source does 2 things. Turns on gas flow and DC power at the torch head. If the water has not completely blown out before the DC gets there the torch is shorted by the water. The power source detects this short and shuts down its outputs.
Thanks
Gene

[barnon]

Thanks for the replies.

I wonder if there is a way to keep the air flowing constantly during sessions.

[LordButch]

As far as I know, there is no way to keep the air flowing during submersion. Only specifically made torches for UWP (underwater plasma) have this trickle flow of gas to keep water from entering. Kjellberg is one plasma company that does this.

[xjdubber]

if you keep the water about half an inch under the metal it will do just great. Ask the hypertherm rep how the arc starts without shorting out?

[barnon]

Another call to a different technical rep confirmed what the last poster said, just keep the water under the metal.

Water Table project is on again.

Thx

[Torchhead]

You can actually let the water touch the back side of the metal (a trick that a commercial shop that cuts lots of Stainless uses). They built a constant level water tray (automatic float value). Even a slight film of water on top will not hurt. The purge air stays on after a cut for several seconds but cannot be counted on to cut submerged. The start air will blow any film of water away prior to the pierce. By having the water with no gap under the material it eliminates 90% of the nasty plasma smoke and minimizes warping and heat discoloration. Ironically, the air to the torch has to be clean and dry!

TOM CAUDLE
www.CandCNC.com