Hypertherm 45 & 1/8", 14g plate

[gamble]

Think I have this thing running but don't want to push it to book speeds which I think are over 250 for 14g. Not sure on 1/8"

What have you guys found as far as speed/amperage/voltage for best results ?

Also as far as height control goes. I can set height distance and voltage. Not sure how it work exactly. Does it follow voltage or height based off where it touches off?

[WyoGreen]

The touch off just establishes the initial starting height. After that, the THC takes over and maintains the voltage which corresponds to the desired height. If the cutting voltage raises above the set voltage, the THC will lower the torch to lower the voltage back to the set voltage. If the cutting voltage drops below the set voltage, the THC will raise the torch to get the voltage back up. The voltage is what controls the cut height.
As an example, my table is a little high on the right side. As I cut from left to right, the torch will get closer to the metal, the voltage will drop, and the THC will raise the torch up to maintain the set voltage, which will maintain the correct cutting height.

Steve

[gamble]

So why even have a setting for cut height?

[Capstone]

So why even have a setting for cut height?

The cut height is determined by the mfr's testing for best overall performance of their cutter on different metals and those cut heights are different for each machine of mfr. . In the case of Hypertherm, they give you two settings; Best Performance and Production. The first is there for people who want the cleanest possible cuts, the 2nd is for people who want max speed with an acceptable amount of dross and simply need things cut faster and typically have automated the cleanup of dross and finishing.

It's up to you to determine what the voltage should be to maintain that height because it can vary based on which way you want to go with your speed.

Assuming your table remains solid throughout it's cut path at the book speeds, your voltage, once set, will ensure that the torch head keeps that cut height regardless of what the metal does during the cut, thus giving you consistent desired results throughout.

[acourtjester]

This is from a cut I made for a church wall hanging from 14 Ga.
Pierce 0.150” arc ok on all the time (added switch ) feather touch surface sensor.
Cut height 0.060” 45 amps fine cut nozzle
Speed 200 IPM very little dross followed by acid dip
Preset volts 82 delay for THC start 1.5 seconds.

[gamble]

So will the voltage vary from machine to machine. So 120v on mine might be .060" off the plate but it may be different for someone else ? Or is it all generally the same

[Brand X]

Mine voltages matches the books in general.. That includes Esab 1600, Victor 152/52, and Hypertherm 65.. Best quality also includes the lowest bevel..

[jimcolt]

Height control sequence that is best for cut quality and consumable life:

1. torch lowers to plate and senses surface (ohmic, torque sense, limit switch sense, etc., depending on machine).
2. Torch retracts to pierce height . (set by operator.....or by setup files in the CAM software)(pierce height is the height for piercing that minimizes consumables damage caused by molten metal blowback)
3. Torch fires, stays at pierce height until the pierce delay times out. (pierce delay (from cut charts) allows for fully piercing the material before any x, y or z movement occurs)
4. As soon as pierce is complete torch indexes down to the cut height (a physical height from the cut chart that produces the best cut angularity)
5. When pierce is complete....x and y motion start accelerating and moving on the cut part lead in.
6. When the machine achieves a percentage of the programmed cut speed (recommended to be about 90%)...the arc voltage feedback control activates. This function monitors the arc voltage (measured between electrode and material being cut).....and maintains the arc voltage that holds the torch at the recommended cut height (physical cut height). On THC's with voltage sampling...this voltage is set automatically by reading the arc voltage once the machine reaches 90% of recommended cut speed....then locks on this voltage. On THC's that require a voltage setting....it is recommended that you do a test cut with the voltage suggestion from the plasma cut charts....if the torch runs higher than the recommended physical height...then reduce the voltage until the height is correct. 5 volts lower will generally lower the torch by approximately .010".....this varies with different plasma systems and power levels.

On height control systems that have an AVC (arc voltage control) lockout speed percentage (as listed above in #6).....the arc voltage control will freeze at the current height whenever the machine decelerates to speeds below the percentage.....this eliminates torch diving on small holes and fine features. Better height controls also have the ability to recognize the voltage change when crossing a cut kerf....and will ignore this, again, eliminating diving.

Hope this helps. Jim Colt Hypertherm

[jimcolt]

Gamble,

The arc voltage is proportional to cut height. The voltage specs in the manual are developed at the book specs for best cut, with new consumables. Almost any of the book specs that you alter....will alter the voltage / physical height relationship:

-lower the cut speed with arc voltage height control active....the torch will get closer to the material. (wider kerf, longer arc = higher voltage...the THC moves the torch closer to thee material to correct to the set voltage)
-Lower the cut air pressure......the torch will get closer to the material. (changing the pressure changes the resistance of the ionized gas stream...which increases the voltage drop between electrode and material...the THC moves the torch closer to compensate)
-As the electrode wears and builds a pit...the arc length (voltage) gats longer (higher voltage)...the THC moves the torch closer to the material as the electrode wears. (THC's that use voltage sampling compensate for this and maintain the proper physical cut height as the electrode wears. THC's with manual voltage settings require that the operator adjust voltage (higher) as the electrode wears to maintain correct physical height).

The reason you have to set some machine voltages a bit different than others....even if running at the exact same book specs...is with the arc voltage reading calibration. The raw arc voltage from a plasma will vary between about 85 volts and over 180 volts (dependant on thickness, consumables and power level). This normally goes through a voltage divider, filtering circuit....which then feeds the THC electronics with a divided DC analog voltage to monitor real time cut height. I find that calibration on many of these voltage divider varies from machine to machine.....or the wiring between the divider and THC may have some voltage drop. Generally.....if you find the voltage for cutting (under book specs with new consumables) is off by 5 volts.....then all of your cutting process voltages for all thicknesses and power levels will be off the same amount.

Jim Colt Hypertherm

So will the voltage vary from machine to machine. So 120v on mine might be .060" off the plate but it may be different for someone else ? Or is it all generally the same