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Effects of adjusting volts and amps

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jhsenterprises
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Effects of adjusting volts and amps

Postby jhsenterprises » Mon Nov 13, 2017 3:12 pm

So I tried searching but couldn't really find what I was looking for. I was hoping to get a better understanding of what adjusting amps down from the recommended settings accomplishes. For argument sake, say I'm cutting 16g cold rolled with a hypertherm 85 using 45amp fine cut consumerables. Why do some people adjust the amps down.

Also I've read where others are turning up the voltages from the recommended amount. I'm pretty sure I read one of Jim's suggestions on doing just this for 14g hot rolled with fine cut consumerables, to the tun of 10+ volts. Can someone explain what this is actually doing?

Mucho thanks

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acourtjester
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Re: Effects of adjusting volts and amps

Postby acourtjester » Mon Nov 13, 2017 3:35 pm

This is a way to get better cuts, sometime the torch works better slightly higher ( higher voltage setting for the THC). Instead of using 0.060" a higher voltage will move the torch up to maybe 0.070" to 0.080" cut height. Doing test cuts with different setting shows which works best for you.
with fine cut I don't go below 40 amps for thinner metal, I don't cut below 18 Ga metal.
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jhsenterprises
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Re: Effects of adjusting volts and amps

Postby jhsenterprises » Mon Nov 13, 2017 6:01 pm

So adjusting voltage adjusts cutting height?

tcaudle
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Re: Effects of adjusting volts and amps

Postby tcaudle » Mon Nov 13, 2017 6:56 pm

on that table the voltage (Preset Volts ) is set automatically base on the tool you pick in SheetCAM. To override the Preset volts you can first load the code and THEN change the PReset volts up or down. As stated increase the Preset Volts to increase the arc gap (height) . You can also bump the volts up or down as it cuts. If you find a better setting for that tool just open the tooltable in SheetCAM , find that tool in the list and change any of the parameters then SAVE the toolset or it won't be there the next time you use it.

jimcolt
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Re: Effects of adjusting volts and amps

Postby jimcolt » Tue Nov 14, 2017 1:18 pm

Yes, voltage preset is proportional to cut height, higher voltage equals higher height.

The height control reads the actual arc voltage as if you had a voltmeter with the negative lead connected to the electrode inside the torch, and the positive lead connected to the work cable that attaches to the workpiece. It then compares the preset voltage (set by the operator) to the actual voltage....if actual is higher than the preset the THC activates the z axis motor and moves the torch closer to the material until the actual and preset voltages are the same. This is how a height control works on most cnc plasma cutting tables.

On some machines / THC's the operator sets a physical cut height. The torch starts the cut at that height (after locating the surface of the plate then moving to the physical cut height) and samples the arc voltage...then locks on that voltage (it is like auto setting the preset voltage)....then adjusts torch height based on the locked on on sample voltage.

Jim Colt Hypertherm


jhsenterprises wrote:So adjusting voltage adjusts cutting height?

jhsenterprises
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Re: Effects of adjusting volts and amps

Postby jhsenterprises » Tue Nov 14, 2017 3:52 pm

Awesome thanks for the explanation on voltage. What about the amps? Why do some people run lower amps, and what does this actually do?

jimcolt
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Re: Effects of adjusting volts and amps

Postby jimcolt » Wed Nov 15, 2017 9:44 am

If you look at the available consumables for a Hypertherm Powermax85 (85 amps maximum) you will see there are 45 amp Finecuts, 45 amp shielded, 65 amp shielded and 85 amp shielded consumables.

Each consumable set is designed to provide its best energy density (amps per square inch of arc area) at its rated amperage. For best quality cuts you choose the minimum amperage set of consumables that the cut charts (in the operators manual for the Powermax85) suggest for your material thickness. Then you set everything (amperage, arc voltage, cut height, pierce height, pierce delay, cut speed) exactly as the cut charts suggest for your material thickness and you can expect a good quality cut. Different sheets of steel have different chemistry.....so on occasion you need to adjust cut speed, faster to eliminate dross (resolidified metal that sticks to the bottom of the workpiece) , slower to produce a squarer edge. speed is the most common adjustment to improve cut quality...though advanced machine operators often will experiment with amperage and cut height (arc voltage) to fine tune for their particular cutting application.

So....running a 45 amp rated nozzle at 45 amps usually provides the best performance in terms of cut quality and nozzle life. If you increase the amperage past 45 (with a 45 amp nozzle), expect very rapid nozzle wear/failure. If you reduce the amperage below 45 amps with a 45 amp nozzle...expect cut edge angularity, slower cut speeds and a higher probability of dross.

Typically: 45 amp Finecuts work best from 26 gauge to 10 gauge, 45 amp shielded work best from 10 gauge to 1/4" (to 1/2" if your plasma only goes to 45 amps), 65 amp shielded are best used from 1/4" through 5/8" , and 85 amps from 1/2" through 3/4". Each of these consumable sets will cut thicker than I suggest if you start on an edge. The upper limits listed here are the maximum recommended piercing capability for each power level.

Voltage is height, higher voltage, higher height. Amperage is relative cutting power, higher amperage = thicker and faster.

Jim Colt Hypertherm



jhsenterprises wrote:Awesome thanks for the explanation on voltage. What about the amps? Why do some people run lower amps, and what does this actually do?


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