Combating unexpected taper issues

[motoguy]

On several occasions I've cut 3/8" or 1/2" material with electrode/nozzle that I assume to be good (new, little use, no blowouts, etc), only to find an unacceptable taper on the finished part. Usually it's a "parallel" taper...good finish on 2 sides, the other 2 sides are tapered in the same direction. After swapping around electrodes/nozzles/swirl rings/shields (after confirming the torch is still solidly mounted/hasn't shifted), and a couple of test cuts, I find a good combo with no taper. I then proceed to cut (or re-cut) the job. It's the 2nd example in this photo..."unequal" bevel:



I'm curious...do you guys just throw thicker material up on your table, cut away, and have quality cuts? Or do you deal with this issue as well? Do you put a test cut in every sheet, just to make sure you won't have taper issues? I've found I can't rely solely on new components...I found a brand new electrode was the reason for the offset taper on one of my cuts. Replaced it with another new electrode, and the cut went fine. Swapped electrodes back on the next (thin) job, and found the offset taper had returned. Brand new electrode.

I've spent the past many months working primarily in gauge material. If I ran into a taper issue, I could usually run a flap wheel along the edge to correct it. I can now watch the cut part, and see if I need to raise/lower the THC voltage, to make up for a worn electrode. When an electrode/tip becomes too worn for "fine" work, I usually shift it to "artsy use only", until it's time to trash it.

Gauge material is cheap, however, compared to sheet. If taper ruins a 14ga part, it's not the end of the world (and it can usually be corrected with a flap wheel or dremel). Minutes to fix, and the whole SHEET costs $50. I don't want to start wasting any sheets, though, when I'm talking 3/8", 1/2", etc material. Hell, it's an ordeal for me to simply load them...mush less waste a part, and potentially have to load another sheet of it.

I've checked to make sure my torch is square to gantry, and it is. I've wondered if this can be an issue due to worn/rough slat tops affecting the material...perhaps it's not setting flat on the table? While I use whole sheets of gauge material, I often use smaller sections of plate material, for ease of handling. These shorter lengths (sometimes only 3-4 slats wide) would be more prone to slat height issues, I think, than a full a sheet. A full sheet would probably "average" it out.

My work load may be shifting from predominantly gauge material, to a large percentage of plate material. As such, I'd like to figure out these taper issues. Input on the issue would be appreciated.

[SeanP]

Well I can't offer any answers I'm afraid only to say it sounds exactly like what I go through with swapping consumables around, although I'm not using genuine parts but I don't really think genuine are any better anyway, I have tried them.
I can usually tell how well it's going to cut in 1/2'' by the slug that comes out of a hole so I will start off by cutting a 1'' hole in a waste area and see how that looks before cutting the part.
I'm using a PM45 I thought your 85 would have been better really with the better torch.

[Brand X]

I would guess you are using the Copper plus electrodes (Best overall quality long term) and 65 amps max on the .500. Then 45 amps on the 3/8. Not sure if I really liked the 45 amps on .500, but I have not cut all that much with my Powermax 65..

The electrode thing shows up with my Thermal 82 (A-60 now) Aftermarket electrodes,but never buy them anymore. Although I have had some luck with the last batch of them..When they start to fail, they either cause bevel issues or somewhat strange voltage readings on the thc..

My Esab 1600/PT-37 torch was one of the better machines in the 1/2-5/8 range overall. That said, my friend cuts tons of .500 MS with his Powermax 85 at 65 amp book specs, and he gets great cuts overall. I swear there are power supplies that are better then others, even between the same exact models. Found that out with Victor, and Esab machines..(Same machine torch, different power supply)Only have one Powermax, so I can't say there...Of course that will totally be denied by the powers to be.. :)Stands to reason since it true with everything else in the world..

[motoguy]

I would guess you are using the Copper plus electrodes (Best overall quality long term) and 65 amps max on the .500. Then 45 amps on the 3/8. Not sure if I really liked the 45 amps on .500, but I have not cut all that much with my Powermax 65..

The electrode thing shows up with my Thermal 82 (A-60 now) Aftermarket electrodes,but never buy them anymore. Although I have had some luck with the last batch of them..When they start to fail, they either cause bevel issues or somewhat strange voltage readings on the thc..

My Esab 1600/PT-37 torch was one of the better machines in the 1/2-5/8 range overall. That said, my friend cuts tons of .500 MS with his Powermax 85 at 65 amp book specs, and he gets great cuts overall. I swear there are power supplies that are better then others, even between the same exact models. Found that out with Victor, and Esab machines..(Same machine torch, different power supply)Only have one Powermax, so I can't say there...Of course that will totally be denied by the powers to be.. :)Stands to reason since it true with everything else in the world..

I have been using genuine Hypertherm consumables, purchased from Baker's. I have not used the copper plus electrode, as I read about them not playing well with the finecuts. I will likely purchase some, as I start cutting more plate. As I mentioned above, the majority of my work has been gauge work, so the finecuts are my primary consumables.

It's been very frustrating to have to re-cut parts, try to track down the cause, etc. Particularly when new consumables are sometimes found to be the cause of the problem. The more I cut, the more I learn about negating "issues" of the past. This one, though, has me stumped. And frustrated.

[Brand X]

There is Thermacut stuff for the Powermax 65/85 Nice stuff and might give you other options if you are not happy. I have some in the 45 amp range and I like them very well.. different shield, nozzle, electrode,and two piece swirl ring..

[jimcolt]

With the Thermacut consumables you completely lose the advantage of the conical flow technology....one of the reasons why users buy Hypertherm. I recommend against do this. Get the built in USA Hypertherm parts and take advantage of the best technology from the company that designed the system.

Regarding taper....with any plasma torch:

- Taper that is relatively uniform around the perimeter of the cut, but excessive, is caused by: 1. Too much power (amperage) for the thickness, 2. Cutting with too much torch to work distance, 3. Cutting at high speed.

- Taper that has two parallel edges with exaggerated angularity indicates a damaged consumable part, usually the shield and or the nozzle. The primary cause of this damage is piercing incorrectly....too close for the thickness or with inadequate pierce delay time. Inspecting the orifice of the nozzle and or shield should be done with a 10X magnifier, look for cratering or micro-notches in the orifice. One pierce too close or with inadequate pierce delay can cause damage that affects angularity.

- Here is a pic 3/8" steel cut at 45 amps with good uniform angularity for an air plasma...angles are marked on the top. Keep in mind that taper is normal, can be minimized by slowing and cutting at lower power with the appropriate consumables. Industrial high definition plasma systems can cut with less taper as compared to air plasma. Jim Colt

Powermax45 edge angle 004.jpg (36.83 KiB) Viewed 6173 times

Powermax45 edge angle 004.jpg (36.83 KiB) Viewed 6173 times

Powermax45 edge angle 003.jpg (28.45 KiB) Viewed 6173 times

Powermax45 edge angle 003.jpg (28.45 KiB) Viewed 6173 times

[Brand X]

Thermacut has there own designs that work excellent.They don't use Hypertherm Patents, they use their own..It's OK for Hypertherm to sell Centricut consumables for other machines makers , but if some one else does it, it's highly frowned on. Cut speed with less bevel is faster with the 45 amp Thermacut nozzle. Tells you something right there in that their design work.I like what they did with their nozzles. They have a retro torch for Hypertherm, and Victor machines now.. Cool, if you feel like cutting the cord.. Very nice people to work with.. They are the sister company of Binzel, and German owned.

[jimcolt]

Thanks for the schooling on that BrandX.

Hypertherm has a large market share in plasma cutting, which means they sell a lot of consumable parts. Hypertherm sells a lot of plasma cutters because they are well engineered, they are reliable, they provide lower cutting costs, and they cut well. They also have support after the sale. Many of the processes and consumables are patented....because Hypertherm puts a huge effort into improving the process. Hypertherm does make parts for other brand mechanized plasma cutters, however they are not copies....and we see no reason to design parts for other plasma cutters unless our engineering team can make improvements cut quality or consumable life (lower operating cost). Most of our designs are protected with patents....which is a way of allowing us to recover expensive engineering costs by protecting our intellectual property rights for a period of time.

Bottom line, there are a thought of companies that want a piece of the consumable business that Hypertherm has because of its stats in the industry. If you make a lesser torch and lessor consumables that bypass the patented technology you will have lower engineering costs. So customers often will buy less effectic consumables that cost less to buy, but cost more to operate (don't last as long, may not cut as fast, may need more secondary work, may have more downtime.) That is a choice of the buyer. It's a free market out there!

The latest Thermacut consumables, made in the Czech Republic,fit into that category, as do a number of other aftermarket suppliers. You take your chances on performance, cut quality and operating cost.

Now......for the original poster (after the subject was changed)..Motoguy, I am happy to help you diagnose your issues with the varying edge angularity. Best bet is to get it solved using genuine consumables as well as cut specs as suggested for the Plasma cutter you have. Picture of used nozzles, shields and cut edges will help.....I have been helping with issues like this for close to 39 years. If you prefer me to work with you on this forum or privately....your choice. jim.colt@hypertherm.com Jim Colt Hypertherm

One other thing I should add is with the Copper Plus electrodes. They do not provide a cut quality adavantage, but do provide a rather dramatic advantage in consumable life (lower operatic cost is the theme again) on materials thinner than 1/2". They work well with Finecut consumables as well....assuming they are used as suggesting in the operators manual. Jim

[Brand X]

It's nice to have another option for people. Thermacut gives you more options then less.. It's also best to try them in your machine, if you are not liking what the factory is giving you. Might be surprised that it's not so black and white as stated above. You have not even tried Thermacut new torch on a Victor or Hypertherm, so saying it's a lesser torch is still a unknown. When you see the cut speed increase, and the Bevel range move up, somebody knows what they are doing with their patented consumables. Yes they hold patents too. Meaning Hypertherm cannot use their ideas either.. You are pretty lucky The Thermacut guys are not bringing in their highly advanced Plasma cutters to the US..They are just deciding to work with advancing the consumable, and torch line here.. Which mean more benefits for others looking for other quality options.

More schooling is good from more then one source. That's how you become smarter, and able to look through what is a obvious conflict of interest, and what is closer reality..

[jimcolt]

BrandX, How about helping the poster responding to his needs to solve the angularity issue. I know you can do that, as can I.

Start another thread if you want to discuss the value of aftermarket consumables as well as aftermarket torches. I would be more than happy discussing the comparisons. And regarding the direct testing we have done with both the US offerings and the Euro offerings from Thermacut....what you don't know may surprise you! Jim

[Brand X]

My point is he is having issues with the standard electrodes, then maybe the copper plus or some other setup, just might get him going in the right direction. Throwing the same new electrodes that some have been causing him problems, screams try something new like the Copper plus, or a completely different setup, to see if it changes for the better.. I never said copper plus would cut better, but they are a good option anyway, and worth using. There are different setups available, and he just might be happier with one of those?

Many times there are settings, and setups that are not in any book, that will absolutely amaze you.. Owning many Victor/Esab/Thermal Dynamics machines proved that to me, and Best quality setting from anyone, just might not be best quality parameters for my table setup..Just the variation in steel makes that so..Also my idea of best quality just might not be the same as a engineer has wrote down. Mine might be elimination of bevel, and forgo getting all the dross off the plate. ETC.... Air plasma has to deal with many things, that some of the higher end machines do not have to deal with. Impurities in the air itself will never be as good as a mixed gas setup in general. I think you get to a point, and the only thing you can do is pick your poison in which defects you are willing to live with.. It's still pretty dang good when the stars line up right..Kind of comes down to the guy running the machine more then people think..(for the best quality you are looking for..)

[beefy]

As a user and a biased customer of Hypertherm cutters, I do think the mention of any aftermarket consumable has relevance here. I've seen this bevel problem mentioned numerous times over the years and often the thread seems to die without a solution having been found. I've had it myself with brand new consumables.

I'd love it if many users who had this issue tried aftermarket consumables. If a simple change out from new Hypertherm consumables to new aftermarket consumables got rid of this bevel issue then that is VERY relevant to the problem at hand. And if it didn't help the problem then that is just as relevant because it has eliminated that solution as a fix. It's always good to also know what DOESN'T work.

I'm glad Brand X has mentioned these Thermacut consumables and I'm going to order some complete sets. If/when I get this bevel problem with brand new Hypertherm consumables, I can immediately swap out for the aftermarket ones and see how they go.

[jimcolt]

Tried and true troubleshooting procedures for a solid process (and the Hypertherm systems are solid) are to go back to the base specs. Book speeds, pierce height, cut height, amperage and a new set of consumables. Here is the way I handle cut quality issues:

1. Open the manual, set everything exactly as the manual suggests.
- Speeds can usually be assumed correct on a machine that has been properly built and has the correct motor / reduction per length of travel settings.
- Pierce height will vary....and should be checked periodically. This is critical and will cause cut quality issues on the very first pierce once you are cutting thicker than about 3/16". This should always be at book settings, though a little higher is ok. The Hypertherm torches are designed to pierce straight in with no x, y or z motion until the molten metal exits out the bottom of the workpiece.
- Pierce delay time in the Hypertherm book is correct, assuming you start the time by using the arc transferred contact closure from the plasma cutter....this contact closure occurs exactly when the plasma arc starts drawing current through the work cable. Some cnc machines start this timer based on other events....such as when the start signal is sent to the torch....which would bee too soon as there is a delay in getting the torch started that can vary with consumable wear, with torch lead length, and with air pressure. You can increase the pierce delay time to ensure the arc penetrates before motion occurs if necessary.
- Amperage....book specs from the cut chart.

2. Consumables....if you are having varying angularity....put everything in brand new with part numbers that match those in the cut charts. Nozzles, shields, swirl rings, retaining caps can cause wildly varying angularity. Electrodes usually do not unless they are worn past their expected pit depth (see the operators manual for inspection procedures).

3. Check torch angularity to the material with a square. Do not use a level. Check both x and y directions and adjust as needed.

4. Check incoming air pressure at the plasma air inlet....with a gauge hard plumbed here. If it is not located right at the inlet it is not accurate. Read this gauge with air flowing at the torch....and check it this same way when your compresses air system is at the bottom of its pressure cycle. Be sure it stays within the Plasma manufacturers specs. Restricted inlet air will affect edge angle and can also cause rapid nozzle orifice wear, as well as rapid electrode pit depth wear.

5. Check cut gas flow or pressure....depending on the plasma system....do this with all of the above done first.

6. Shut off the height control and initial height sensing (pierce height) and program a rectangle with radius corners (like the one in my previous post) and with a long straight lead in (maybe 1/2" or more) that can be positioned to start with the torch centered on the edge of the material. Set the torch at the correct physical cut height using a thickness gauge.....advance the torch in trial mode (no arc) around the part to determine that the height stays accurate for the entire rectangle.

7. Cut the part....observe the edge angularity on each side. You will notice that the part I posted shows some variation......which is normal with any plasma, more so with air plasma than an oxygen high definition plasma. 3/4" should have edge angularity of about 2 degrees, 1/4" will have edge angularity at 3 to 4 degrees, assuming you are matching the power to the thickness (85 amps on 3/4", 45 amps on 1/4")

8. If the cut looks good as done in #7.......do another cut piercing the material, not edge starting. On some steel plate with different levels of carbon, manganese and other metals.....you will see the pierce slag pile stick to the top where the pierce occurred. Be sure your lead in is long enough and position properly so the slag pile does not cause a torch to slag pile collision at the end of the cut.....which can damage consumables and knock your torch out of square. Spraying anti-spatter spray on the top before piercing can help this. If I have to do a lot of piercing on thick material....I do another cut layer that only has all of the pierce points.....I pierce all pierce holes, knock off the slag piles , then edge start on the pierce holes to do my cutting, just like in #7.

9. If after all of the above is done accurately and methodically....and you still get wildly varying angularity when doing the non pierce cut in #7, then you could have an air flow / pressure issue internal to the torch, the torch leads, or the internal plumbing of the plasma cutter. Time to contact tech service for advice.


The above is good troubleshooting for wildy varying angularity with a Hypertherm system. If you don't follow a systematic step by step procedure like this....you will simply keep digging a deeper and deeper hole into poor cut quality land. Hypertherm has done their lab work, the book specs work (and yes BrandX, there are always other specs that may produce the desired result as well). The worse thing you can do when there are cut quality issues is to buy aftermarket consumables or torches......get the factory system working first....then if you want to gamble with another company's parts on your top of the line plasma cutter, go ahead. Kind of like putting some old bias ply tires on your new Corvette.....

Jim Colt Hypertherm

[sphurley]

Quickest way to ruin a new set of consumables is to test fire a 45amp consumable, with the PM set at 85. Don't ask me how I know that.

[Brand X]

I read this a while ago, and I think it still has merit to this day..(8 year old post..) Post #12 is interesting, and along the lines how I think.. :)Yes Hypertherm has moved forward, but Thermacut sure has not been stuck in the mud either.. I am going to do some more cutting with my Hypertherm 65 with both Thermacut 45 amp , and Hypertherm 45 amp consumables.. That's how I do it, but I guess it has no real value other then I get to see what works for best for me. (Usually Victor anyway, because of lots experience with them ) I figure It might not be be politically correct to think out of the box, but my machine, and my rules..

http://www.cnczone.com/forums/general-w ... ables.html

[motoguy]

- Taper that is relatively uniform around the perimeter of the cut, but excessive, is caused by: 1. Too much power (amperage) for the thickness, 2. Cutting with too much torch to work distance, 3. Cutting at high speed.

- Taper that has two parallel edges with exaggerated angularity indicates a damaged consumable part, usually the shield and or the nozzle. The primary cause of this damage is piercing incorrectly....too close for the thickness or with inadequate pierce delay time. Inspecting the orifice of the nozzle and or shield should be done with a 10X magnifier, look for cratering or micro-notches in the orifice. One pierce too close or with inadequate pierce delay can cause damage that affects angularity.

- Here is a pic 3/8" steel cut at 45 amps with good uniform angularity for an air plasma...angles are marked on the top. Keep in mind that taper is normal, can be minimized by slowing and cutting at lower power with the appropriate consumables. Industrial high definition plasma systems can cut with less taper as compared to air plasma. Jim Colt

Jim,

Is 3 degrees a good number to use to calculate taper for a properly cutting HT air plasma setup? I'm trying to determine how much material/oversize to allow for holes in various thicknesses in my drawings. If I use 3 degrees, then 1/2" material will have about .026" of bevel, 1/4" is .013, etc. I'd like to put together a good starting place, for things like the lug holes I cut in the plate below. My digital protractor showed just under 2 degrees of cut (1/2" material cut at 45A process from 45xp cut chart), but I don't expect it to be ultra precise.