Welding Tips and Tricks

Hi, my name is Dmitry and I'm a brand whore.

I am also not rich, sadly. My first welder was/is the Lincoln 180 MIG PAK, which has served me flawlessly, even got the spool gun for aluminum welding. I waited for the right opportunity to snag the right TIG, getting the Dynasty 210DX at a trade show and generally all the rest of my gear is Miller. If I find the right buyer for the Lincoln this year, I'd like to get the new 211 Millermatic.

Meanwhile I was eyeing plasma cutters. The Miller 625 is 1800 bucks and at that price it's just a pipe dream. The TIG is more expensive but there's no substitute for it. I looked at a plasma like a microwave oven - if you can't afford one, you can get by without it just fine. Then I found out about the ebay Chinese plasma cutters and at 300 bucks shipped, including a pile of consumables, it would be a fun mistake at worst. I've had it for over a year now and I'm left wondering, what do I get for 6x the money? As long as my crappy single stage compressor can keep up, it will do everything and as far as I can tell, do it well. I've cut up to 1/4" alu and 1/2" steel with it.

If you've used both, owned both or happen to know from a first hand account - what do you gain with the much more expensive Miller or comparable plasma cutter? I don't know how accurate it is but the Ebay one is rated singificantly higher (Miller 625 40A @50%, China 40A 100%, 50A 60%)

Hey Dmitry.

In my humble opinion, there is no straight answer, as there are so many different uses, needs and variables. If you are using the plasma as part of your business, what you absolutely must have - and perhaps what you get with a big brand - is decent backup, so should anything happen you can access service and get it fixed fast.

My Tig/Stick/Plasma unit is Chinese, but I purchased carefully from a reputable storefront and the seller offers instant backup every single time. I've never had a real problem, but if I do I know that the guy is at the end of the phone ready to send a whole new machine overnight if necessary. Of course this isn't always the case with the China stuff.

If you are a hobbyist and can buy Chinese from a dealer who offers great backup, parts and service, why not? I'm not in a position to comment on the finer points of comparative performance, but there is a plasma specialist on this forum who will no doubt chime in sooner or later to cover that.

Glad your machine is performing well.


Kym

Plasma -- Hypertherm, nuff said.

OK, I will make an attempt to explain the differences in plasma cutters from a major brand as compared to plasma cutters that come from China (and cost a fraction of the price). First though....I am Jim Colt, a 38 year veteran with Hypertherm......as the 11th Hypertherm employee (approaching 1600 today) I have had the opportunity to work in virtually every facet of plasma cutter design, manufacturing, sales, marketing and even in inventory control positions. I am not going to specifically try to make Hypertherm look better in this post, just provide comparisons as I know them. I do have the privilege of being able to walk into our large reliability test labs where we have almost all brands and models of plasma cutters at our disposal. I can (and have) cut with almost all of them in both hand and cnc cutting applications. So...here is what is different between "ours" and the low cost Asian imports.

- Power output......when buying a plasma we look at the amperage as the relative cutting power for comparison. We think that if it is a 40 amp system it will likely cut as thick and as fast as all other 40 amp systems. In reality the true power of a plasma cutter is the amperage multiplied by the load voltage capacity of the plasma power supply, amperage x voltage = wattage, and a plasma power supply that can produce a higher wattage without exploding internal components (like FET transistors or IGBT transistors) will have more power....regardless of the amperage.

The math. There is a popular 40 amp import plasma that produces 40 amps, and when you read the fine print in the tech manual it can provide a safe load voltage of 96 volts DC. 40 (amps) x 96 (volts) = 3,840 watts. There is a popular 30 amp US built plasma cutter that is advertised to produce 30 amps. It can provide a safe load voltage of 125 volts DC. 30 (amps) x 125 (volts) = 3750 watts. The real power of this 40 amp import and the 30 amp domestic plasma is almost the same. When you cut with them you will actually realize that the 30 amp system cuts very similar (actually slightly faster) on thick materials compared to the 40 amp import.

The 45 amp US built plasma from a major manufacturer actually has a higher wattage output than almost all of the 60 amp low cost imports. What does higher load voltage buy you? Load voltage is what controls the effective length of the cutting arc. higher cutting voltage is required to cut thicker materials. When you cut beyond the rated load voltage...by forcing the plasma cutter to cut thicker than it should cut....you will exceed the rated voltage and overheat the switching devices in the power supply.....which can end, or shorten the life of that power supply!

- Torch Design. Most of the import low cost plasma cutters use a torch that was produced by another company...and is a universal design that will work on almost any plasma cutter within its amperage capacity range. Most of these torch designs are copies of older technology US designed torches....some over 30 year old technology. A major US plasma system manufacturer designs and builds their own torches (and power supplies) and they are designed to work together. When you buy a 30 amp plasma from this company it comes with a torch that was designed concurrently with the power supply, tested with the power supply, and optimized to work best with the power supplies output characteristics. Why is this important?

Here's why. Plasma torches develop an ionized gas arc internally (between the electrode and nozzle) then add DC energy to that electrical arc to increase its temperature up to the 25,000 degrees F. range. This 25,000 degree arc is then forced through a copper orifice to make the arc perfectly round and increase its velocity. Copper melts at about 1100 degrees F. You will typically get about 120 to 250 starts with the older torch and power supply technology that you get with the imports...then you need to change the electrode and the nozzle. With the latest torch designs (and yes there are multiple patents pertaining to design and manufacture of internal components on these newer tech torches) you generally can achieve between between 900 and 3000 starts on one nozzle and electrode before they need replacement. When you do the math here you will see the imports consumables are cheaper to buy as compared to the US (newer tech) consumables, however when you factor in the longer life of the better technology.....it is clear that it is far cheaper per foot of cut as compared to the imports.

Wait.....so a 25,000 degree arc is passing through a small hole in the copper nozzle (melts at 1100 degrees). How is that possible? There are a lot of laws of high temperature physics that occur inside all plasma cutting torches. If you can stretch these laws to their utmost without going too far.....life of the consumables can be improved. In the newest tech torches careful design of the air flow that goes through the swirl ring and enters the inner chamber of the nozzle provides a unique and accurate gas swirl pattern that acts as a centrifuge. This swirling, hot gas centrifuge slings the cooler (heavier) molecules of gas to the outside of the nozzle bore....where they create a cool, non conductive boundary layer that protects the copper nozzle from melting. There is an attempt to do this with the older tech torches.....but it does not work nearly as well. Note that this is one feature of a well designed torch....I'd rather not outline all of the technology, and there is much more!

So the above is why one reason why a nozzle lasts longer (another is conical flow technology that cools the orifice exit and increases the arc energy density, but that is another subject), so why does the electrode last longer in a new technology torch? It was discovered (back in the 1980's in Hypertherm labs) that during steady state cutting the electrode emitter, which is a small slug of hafnium (an earth element)....remains in a molten state (it melts at about 3000 degrees F). When you release the trigger after a cut the post flow cooling air pulls a small slug of that molten hafnium and spits it out through the nozzle orifice. After a number of cycles (120 to 250 with the older tech torches) enough of the hafnium is gone so cut quality is affected....cut angularity increases, more dross is evident, and soon after you see green flame emitting from the torch when the copper part of the electrode is then consumed. On the US made systems where the torch is designed with the power supply....special ramp up and ramp down air pressure and amperage profiles are developed that minimize thermal shock to the electrode when the electrode initially goes from room temperature to 3000 degrees (beginning of a cut) and ramps down at the trigger release to re-solidify the hafnium emitter. Boom, dramatically longer electrode life. Each power level and power supply / torch design requires different microprocessor controlled profiles, and that is one reason why torches and power supplies should be jointly designed by the same team of engineers.

Reliability. This feature can be designed into any product, however it requires a ton of design and long term testing to ensure that what you designed will really last the test of time. At one US plasma cutter company when new systems are designed and the first "alpha" build (maybe 10 to 25 systems) of pre-production systems are complete.....they then go into a high tech reliability lab. In the lab they are connected to a plasma torch and are modified to produce 10% higher amperage (that they will produce as products) and the chamber temperature and humidity levels are increased to as much as 30% higher levels than the design specs...then all of these units are fired up and do actual plasma cutting under these conditions. The lab techs monitor each closely...and when a unit fails (they are expected to) they are dissected, the failure mode is evaluated, some redesign work is done and the units are all updated...then back in the chamber. The torture tests continue until system failures cease, often taking between 10 and 18 months to get to this point. This makes for long new product development cycles, but very reliable products. I did not mention the other torture tests that include the "shake and bake" vibration, oscillation, heat chamber, and the dust chamber, and the dreaded "drop test". Not so sure the imports go to these extremes, but if you want to see these tests first hand I know where you can get a tour!

In reality all plasma cutters have one thing in common, they cut metal rather fast and rather economically.
So......there is a heck of a lot more to compare such as features, cut speeds, colors pricing, etc. You can all do that by looking at brochures and talking to sales people. Does everyone need a high quality (read expensive) plasma cutter for their hobby shop?, I don't think so. Granted you are taking a bit of a chance on reliability, but heck...that's what warranties are for. And so what if the consumables cost more (because you use a lot more )....you probably won't use many with your occasional use anyway.

The arguments for paying more for a plasma cutter from a major company:
- There is a real factory that will supply parts and tech support for decades.
-Often there are upgrades and improvements (torches, specialty consumables, etc.
- Documentation is usually light years better, operators manuals, cut charts, service manuals, etc.
-Consumables are usually available at the local welding supply store or with a quick click online.
- You have a good quality tool that your kids can inherit.
-If you are using this cutter to earn a living....you can trust that it will be very reliable , and that support is a phone call away if needed.

Jim Colt Hypertherm

What a post! I vote sticky/FAQ. Thank you!

plain ol Bill wrote:Plasma -- Hypertherm, nuff said.

What Bill said...
My LWS is a Miller dealer and service center, shop I worked at last year was looking at a Miller Plasma cutter, they told us to get the Hypertherm, not Miller

Great explanation Jim.

Theres a Chinese 300$ plasma cutter in pieces in my garage. Friend gave it to me. It looks like a High School electronics project inside. The power supply part of it is bad, and the HF start on it never worked. Funny, it never had a ground wire for the power supply.. Piece of crap. I bought my John Deere 212 tractor for 300$... You can do better with 300$

cutmaster 42

Let me first say that my welding equipment is strictly for hobby purposes. As such I do not have to have to cost justify my purchases nor worry about ROI etc. And, if at all possible, I purchase my "toys" from US manufacturers. That said, let me relate my Hypertherm story...

A few years back I decided I wanted a plasma cutter. I purchased a Hypertherm Powermax 30 - the little baby model (rated 1/4" but I have severed 1/2" +). I purchased the unit on-line from the vendor where I had purchased a Dynasty 200DX a couple of years earlier. When the unit arrived I unpacked it on the bench. I turned the unit upside down to verify the serial number. I heard a tinkle tinkle tinkle as something metallic bounced through the inside of the machine. I turned it back upright and heard a tinkle tink and that was it. I shook the machine and heard no more sound. Oh $#&t - something hung up somewhere in the machine. Probably on the circuit board. I can just see the smoke leaking out

I pulled the cover and closely examined the innards. I could find no foreign matter (no pun intended). I put the unit back together and decided to take a break and do the on-line registration. I sent an email to Hypertherm customer service explaining my concern. When I went back to the shop I found that I had neglected to reinstall the cooling fan shroud. I took the unit apart a second time, examined the innards a second time, installed the shroud and replaced the cover. By this time I was tired of playing this game and I figured "it is under warranty" so I plugged the unit in and powered it up. No smoke. When I unrolled the gun cable I found that an 8mm brass nut had apparently fallen out through the cooling slots on the case - thus the tinkle and a half when I turned the unit back upright. The nut on the bench under the coiled up gun cable.

Back to the computer and I found an email from the Manager of Hand Held Products (I think his title was something like that) apologizing for the issue and offering assistance. This in less than an hour! I emailed back that I had found the offending object and things seemed to be OK.

The next morning I took the dog out for our early morning walk. When I got back (about 7:45 AM) the wife was up and mad as H. "This person called twice - says to call him as soon as you get in - he has a meeting at 8)." The person was a repair technician at Hypertherm. He explained that he had been assigned the issue and had gone though a Powermax 30 to determine where an 8mm nut was used. There were only two places (main power wires to the gun I think) and he offered to walk me through pulling the cover to check that he nuts were in place. I thanked him and explained that I had already had the cover off twice and I could do so again to check the connections. They were tight. Apparently a loose nut had fallen into the machine on the assembly line.

The point of this story is CUSTOMER SERVICE. How many times have you attempted to contact a company, especially by email, and never receive the courtesy of a reply? In this case I received a reply in less than an hour from a senior manager AND a personal followup the next day.

I cannot say that some of the overseas companies do not have decent support. That I do not know. I do know that I have received excellent support from Hypertherm, Miller and Hobart.

Ken

My bad - actually I purchased the Dynasty 200 DX from the same place as the Hypertherm - it was first. I did learn how tough Hypertherm units were in the interim. I decided to take an evening "continuing education" welding course at the local Community College - so I could play with some of their machines and try pulse TIG before deciding if I wanted to upgrade my Diversion 165. The instructor was a (fill in the blank). How he got through the 10 weeks without someone being seriously injured I will never know. Had one father and son team welding in tennis shoes, shorts and polyester shorts. No concept of safety. I know the welding program director quite well - suffice it to say they have a new instructor teaching the course.

As to Hypertherm... The school had some older Powermax 60s which were quite abused. After the instructor's introduction of the machines the students were let loose. A plasma cutter does not do very well without the ground wire attached, with the wrong electrode installed, with the nozzle burned through the side. After their first experience I do not think anyone would have had a plasma cutter if you gave it to them.

As I had a Hypertherm and understood how they worked I tore down the guns and installed the correct consumables and made sure the ground wires were properly connected. The machines now cut like they were supposed to. No worse for the abuse.

Ken