Hypertherm 1650 excessive tapered cuts

[PlasmaGuy]

I am a huge fan of Hypertherm and their support group.

With that said, I would like to see if there are other 1650 users that are seeing excessive taper in their cuts?

I called to ask if the capacitors can lose their power but still cut but w/o the original power.

The only problems I have had with machine were in the circuit boards... something internal would blow and trip my main 200A 3 phase panel.

My cut speeds, tip height, amperage and air pressure are unchanged.

Hopefully Jim Colt is reading this weekend and can offer up his opinion?

Thanks

Tom

[jimcolt]

In general....there is not normally an electrical problem that causes cut quality issues. You have not provided much detail regarding "tapered cuts"....so let me ask a few questions:

1. Is the 1650 mounted on a machine...or hand held?

2. Assuming it is on a machine....is there a THC (torch height control system)?

3. Please provide details about the machine and THC.....machine motion, torch to work distance and pierce height and pierce delay times are definitely top ten suspects when cut edge angularity is an issue.

4. On what materials are you seeing the taper? Is the taper uniform around the perimeter of the cut....or does it change?

5. What consumable sets / power levels are you using for each particular material and thickness? If you operate at 100 Amps on 3/16" material....expect very high cutting speeds and a lot of taper. If you use the FineCut consumables at 35 Amps on 3/16"...expect slower speeds and minimal taper. Matching the consumables and power level to the material and thickness is key to best cut quality. The best starting point is to follow the recommendations in the Hypertherm manual....there are cut charts for FineCut consumables as well as 40, 60, 80 and 100 Amp shielded consumables....each set has its sweet spot for cut quality.

5. Air pressure, air flow rate, air purity.......we all keep hearing about this....and I find that over 50% of plasma system user don't seem to believe what we say...moisture or oil in the air will damage consumables in the first few seconds of use. These damaged consumables will still cut...for a long time...but the damage causes poor cut quality in terms of dross and bad angularity (taper)

6. Pierce height/technique. One pierce too close to the plate damages the nozzle shield orifice. Always pierce at 1.5 to 2 times the recommended cut height. Pierce delay time must be long enough to ensure that molten metal is blowing out the bottom of the plate before the torch starts moving.

Please get back with more detail and we'll try to help you out!

best regards, Jim Colt

[PlasmaGuy]

1.Machine
2. Yes, Technogon brand
3.Jim, My system is a Torchmate using the Microkinetics Superscribe system...DOS an old gal to say the least. Pierce height is 0.125" . Dwell / pierce delay is 0.75s
4. A36 mild steel . Uniform around the cut
5. I operate using 100A consumables 99% of the time. Half inch material is my most common material too.
6. I have a refrigerated ar dryer but will say that I have not had it on this month.... maybe the problem? Air pressure is OK
7. On pierce height I have one of Leons old proximity sensor machines so I start manually most of the time with my pierce.

Thanks Jim!

Tom

[jimcolt]

Tom,

You can get better cut quality in terms of square edges on 1/2" steel by using the 60 (best) or (80) amp consumables. The 100's will do an excellent job on 1/2"...but there will be more taper than at lower power levels. Don't just run the 100 Amp consumables at lower power....this will reduce the energy density of the arc...resulting in worse quality.

If you look at the operating charts in the Hypertherm manual....you will see that the proper cut height for 100 Amp cutting is 1/8" (.125").....pierce height needs to be set at 1.5 to 2 times the cut height....so you should be piercing at 3/16" to 1/4". One pierce at .125 on 1/2" thick steel is enough to damage the nozzle orifice and/or the shield orifice. You can inspect these orifices with a magnifying glass (I use a jewelers eye loupe)....compare a used nozzle orifice with a new one.....you are looking for a perfectly cylindrical bore with sharp exit edges....no rounding, no nicks. The nozzle shapes the arc....and if it is rounded or unconcentric in any way...then the arc will take on the shape of the nozzle bore......and lose energy density, causing varying taper in the cut. Pierce height is very critical.

Does your machine have arc voltage height control to control torch to work distance real time? If you vary more than about .010" from the recommended cut height of .125"....then expect more taper in the cut edge. If your taper angle is the same all the way around the perimeter of the cut....you can reduce it by cutting slower, and cutting with the torch closer to the plate.......just never piece closer than mentioned above pierce height.

Jim

[PlasmaGuy]

Jim,

My height control is via 3 proximity sensors. At the time Technogon had not started to offer the Arc Voltage HC option. My THC in primitive at best.

With that said I have had 4 years of perfect cutting with this system. And with my dwell and pierce heights too.

This is why I am curious if the I may be having some weakening caps or other internal stuff?

As to using a lower amperage electrode and tip I learned something new. Bigger/larger isn't always better!

Thanks Jim!

Tom

[jimcolt]

OK....I now understand that it was cutting acceptably...and now something has changed!

I still don't believe there is anything in the electrical/electronics in the power supply that will cause this. Usually...as I said befor it is gas pressure or flow related.....we already talked a little about that....but there also can be problems downstream of the gas components in the power supply.

If you have not changed the torch retaining cap recently....try that. Same with the swirl ring. Check the orings on the front of the torch. Last but not least.....try to convince your local Hypertherm distributor to bring a whole torch and lead assembly to your place...or borrow one for a day. Even a minor leak or restriction in gas flow....which can be caused by any of the above...could result in bad angularity.

Jim