[Ed Williams]

Could someone explain to me what is the difference on the cheap Chinese IGBT pilot arc machines over Hypertherm and Thermal Dynamics. Why they work on plasma tables and the Chinese IGBT pilot arc will not.

[jimcolt]

Plasma systems are not all the same. The process....in order to make the torch consumable parts provide a good balance of performance (excellent cut quality throughout the life span of the consumable parts) requires some serious engineering work in the high temperature physics arena. Ultimately, the plasma power supply must be designed with the torch and consumables in order to take full advantage of the laws of physics.....the arc temperature can reach 50,000 degrees fahrenheit.....so it is critical to co-ordinate power supply output to the cooling requirements required by the torch....current ramp up, ramp down, gas pressure and flow and timing, as well as the use of the gas (air in air plasma machines) to channel cooling to the nozzle, electrode and torch body while also using it to create the ionized plasma gas can by very tricky. In my 32 years in the plasma cutting industry.....I have seen the largest improvements in air plasma system performance invented in the last 5 to 10 years.

So, the differences between a high end air plasma system and a low cost chines import are many.....let me try to cover some of them.....and of course there are different system designs (both import and US made products)....so not all of the comparisons are true in all cases. I will use a Hypertherm Powermax45 (probably the highest level of performance in a US made Plasma in the 45 Amp range) as a benchmark.

Torch.

The Powermax45 torch was designed as a system with the power supply. It closely matches the output characteristics of the power supply for best performance. It is a shielded (can drag at any power level) torch with the latest "conical flow" technology that helps to constrict the arc for higher energy density, resulting in narrow kerf and extremely good edge quality, and consumable life that is typically 3 to 6 times longer than other air plasma torches. You will notice that Hypertherm has a new torch for every new plasma design.....that is because we are constantly developing new technology...and the company mantra dictates that new systems must use the latest developments to make them perform better than our existing products....or else there is no good reason to develop a new system!

Most of the low cost Chinese imports use a 25 plus year old copy of an Esab PT31 torch. This torch is a high frequency start torch....and can be used with a pilot arc start process or with a "scratch start" process....regardless, it requires a high frequency arc starting circuit. Regardless...this is an unshielded torch...meaning that if the nozzle contacts the plate (drag cutting...or just a shaky hand) the nozzle will get damaged. So, most low cost import torches with "pilot arc" start.....use high frequency...which usually cannot be used on entry level cnc machines that use a standard PC as the controller...the high frequency emits RF (radio frequency) electrical noise which will affect low voltage , low current electronics such as unprotected PC's and drive wiring. Further, this older torch design is primitive in its ability to cool and constrict the arc.....the consumables are inexpensive, but short lived. If you do the math...the more costly consumables in the Hypertherm torches are far less expensive (last longer, cut better, less secondary operations.)

Power Supply

The Powermax45 Power supply as a lot of technology built in. It is designed to automatically ramp current for gas ionization, pilot arc, and transferred arc modes, also has the ability to switch rapidly between cutting current and pilot arc current levels....if you desire to cut expanded metals. The system has an extremely high duty cycle for an air plasma.....and Hypertherm rates their duty cycle at 104 degrees F, at a load voltage of 150 volts at 45 amps output. The toughest rating in the industry. If you use this system beyond its ratings......say cutting material thicker than it is rated for on a 120 degree day....you will not damage it as multiple heat producing internal components are protected with thermal switches....it will indicate an overheat condition, and will disallow the arc until it has cooled. The 45 has has a clean side/dirty side design, as well as a thermal switch controlled fan. The fan only runs after it detects a rise in temperature....this keeps shop dust from pulling through the machine whill at an idle...or even while cutting at lower output power levels. Air that travels through the unit while the fan is running only passes by heat sinks and components that will not be affected by shop dust.....the sensitive electronic and circuit board side disipates its heat through the divider wall and through the heat sink. (picture below of the inside of the Hypertherm unit). The Powermax45 has a cnc interface built in....accessible from a receptacle on the rear panel.....it offers a plasma start input (not functional with hand torch installed), an arc transferred output, and a 50:1 divided DC voltage output for torch height control reference voltage. It also has a quick disconnect torch that allows you to switch from a hand torch to a machine torch in less than 10 seconds with no tools. The 45 has a boost conditioner circuit that allows for use on low input power line conditions....or for remote generator use whee the input voltage may vary.....input voltage variations (within reason) will not affect the operation at the torch...and will not damage the power supply. The Hypertherm system has a safety trigger.....you have to specifically want to fire the torch wit this flip down trigger safety.....and also has a parts in place sensor at the torch that will shut down the power supply before you start to unscrew the retaining cap on the torch to change consumables.....plasma torches have as much as 370 volts DC on the electrode..... There's a lot more....

The low cost imports do not use special ramp up techniques that will lengthen consumable life. My testing shows that their duty cycle claims are incorrect......also, I have never seen duty cycle ratings that offer full output current at a given ambient air temperature and a given load voltage. Most internal components do not have overheat protection.....and there is no attempt to keep shop dust, which is usually conductive...from coating internal electronic components. There is no means of operator safety at the torch....usually no UL or CSA safety approval.

Typically....you want to campare a system like the Powermax45 to at least a 60 Amp import. The 45 will cut most materials faster, will sever thicker materials......will be safer to operate, and will be serviceable for many years. The Hypertherm is 100% designed and manufactured in the USA by employees that own the company.

I realize there is a need for low cost entry level equipment...in my younger days I relied on this type of equipment to learn the metal fab business. There is however....no comparison in terms of cut quality, reliability, serviceability and long term operating cost. Pay more up front.....it is less expensive to use....and it always works. If purchase price is a big factor...look for used major brand systems that are 5 or 6 years old...often a much better system than a new import.

If there are specific questions...I'd be happy to answer. I have disected a few of the imports...and as I said earlier, some are better than others!

Jim Colt



First three pics: inside of a Hypertherm....dirty side (no critical electronics), top, and clean side with the conformal coated board. Next three: Chinese 60 Amp unit....complicated wiring, a lot of exposed connections in the air flow.

Could someone explain to me what is the difference on the cheap Chinese IGBT pilot arc machines over Hypertherm and Thermal Dynamics. Why they work on plasma tables and the Chinese IGBT pilot arc will not.

[Pure-Powder]

Jim, want your take on the Thermal Dynamics A80... Good , Bad, ???

[jimcolt]

Thermal Dynamics makes good systems. If you look closely with the specs on their A40, A60, A80 and A120 systems...they have played a little with the specs in order to provide units with higher Amperage output than similarly priced Hypertherm models.

They mention an 80% duty cycle for the A80.....and they mention that the unit will cut at 100 Amps output power.....yet there is no mention of the temperature rating of the duty cycle and no rating of the arc voltage output that is used to create that 80% duty cycle. Plasma cutters capacity is actually created by their Wattage output.....the higher the wattage output, the faster and thicker the unit will cut...regardless of the Amperage.

The A80 is rated at 12 killowatts output....which is similare to the Hypertherm Powermax1250 output. If you look at the published cut charts...the A80 cuts 1/2" steel at 40 inches per minute at 80 amps output.....yet the Hypertherm 1250 cuts 1/2" steel at 60 inches per minute at 80 Amps.......actually the Powermax1000 from Hypertherm cuts 1/2" steel at 42 inches per minute at 60 Amps output.

I also notice that you have to pay extra for the voltage divider output from the Thermal units....it is standard on the Hypertherm Powermax systems....this output is used for torch height control feedback on cnc machines.

So.....it seems like there has been some manipulation of specifications to sound like the A series at T-D have higher output power in Amps.....but the cut charts show that their 80 am p output cuts at the same speed as the Hypertherm 60 Amp......I have not tried the units yet...so I'm not quite sure what is going on there!

Regardless....T-D does make a great plasma system......I would suggest when comparing systems...look at the cutting capacities and the speed, and try to find out at what temperature and voltage the duty cycle is rated at.....that is what determines the true capacity of the plasma.

Jim, want your take on the Thermal Dynamics A80... Good , Bad, ???

[Pure-Powder]

Thanks again Jim for the quick reply... I will do a little more investigating.

[Torchhead]

Ed: If the IGBT (they all use IGBT technology BTW) units you list can start an arc above the metal without having to manually contact the work, and will pierce above the metal then there is no reason it won't "worK" for a plasma table BUT....(you knew there was a but!) how well it cuts is another issue entirely. The quality of the cut has a lot to do with torch technology and the domestic vendors have better technology. It seems counter productive to spend a lot of money on a CNC table THEN use a Plasma that will not let you take advantage of the money you spent.

Can you get different nozzle sizes and tip shields?. You can't cut with CNC and any automated Torch height control using a drag tip. How expensive are the consummables? Can you get them easily. How is the support for the product? Can you get it worked on?

Sometimes the true cost of a solution is more than the initial price you pay.

TOM caudle
www.CandCNC.com

[bullethead67]

I have a CUT80E that i have been working on getting up and running for a while now. I have spent a considerable amount of work getting the power supply adapted to a thermal dynamics machine torch. I have also finally got the multiple ground loops worked out with the exception of 1 that is preventing my torch height from working. Unfortunately the torch tip has to be extreemely close to the work surface to fire. Too close in fact. between the closeness and the non working Torch height I am ruining tips at a record rate. I have put a great deal of effort into getting the cheap chinese cutter to work but i am bull headed, This is a hobby, and I dont need the machine to make money. I am sure i will get the torch height working and be able to cut but the close proximity of the torch to the work surface is still a problem that i dont have a solution to. If no solution presents itself I will be purchasing a Hypertherm or Thermal Dynamics unit.

[asuratman]

Hi Jim,
Is there any new model will be released for a machine the same class as powermax 45 with better tech? Its just question before buying powermax 45. Thanks.

[jimcolt]

Hypertherm has a very large research and development team and prides itself on it engineering capability.......we are always working on new process and product development. Unfortunataly it is our policy to keep our product development secret until we are ready to release products....this is to protect our intellectual property rights (patents, etc.)....and to not tip our competitors off as to what direction we are headed!

Boy did that sound like a statement from a corporate guy...or what! I do keep up on our product development.....and am allowed in our development labs....which I like! If I let out any secrets I would be banned.....or fired.

Best regards, Jim

Hi Jim,
Is there any new model will be released for a machine the same class as powermax 45 with better tech? Its just question before buying powermax 45. Thanks.