Shield Arc
Super Member
Don't you just love these forums? Everybody gets to throw their 2-cents in. 
For those with a Plasma cutter...
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jimcolt
Gold Member
Remember that there are advantages either way.....with water tables or downdraft tables. Here are a few points to consider:
- Water table is very effective at eliminating smoke and fumes....is relatively inexpensive to build and maintain.
- Best fume control is with water in contact with the plate being cut....as water gets lower, fume control is diminished.
-Water contacting the plate affects cut quality with a rougher cut edge and higher chance of dross. To minimize dross and roughness, lower the water...at the expense of fume control.
- Water splashes on the plate and the machine...staining and rust are the result.
-Many shops in cold climates can be below freezing at non occupied times. Anti freeze cannot be used as it will react with the plasma and create potentially hazardous fumes, therefore the water in the table should be protected from freezing....stock tank heaters work well.
-Downdraft tables must be ducted through a welding filter, or blown outside if permissable.
-Cut quality is best with a downdraft table.
-The air flow for a 4 x 4 table is typically 3000cfm to 5000cfm to completely remove fumes
-No freeze problem, but when the blower is blowing outside....heat is also being removed from shop.
-No water staining, better edge smoothness, minimal dross formation.
I have one table with a downdraft and one with a water table. I prefer the downdraft for cut quality and stain rust issues.
Jim Colt Hypertherm
- Water table is very effective at eliminating smoke and fumes....is relatively inexpensive to build and maintain.
- Best fume control is with water in contact with the plate being cut....as water gets lower, fume control is diminished.
-Water contacting the plate affects cut quality with a rougher cut edge and higher chance of dross. To minimize dross and roughness, lower the water...at the expense of fume control.
- Water splashes on the plate and the machine...staining and rust are the result.
-Many shops in cold climates can be below freezing at non occupied times. Anti freeze cannot be used as it will react with the plasma and create potentially hazardous fumes, therefore the water in the table should be protected from freezing....stock tank heaters work well.
-Downdraft tables must be ducted through a welding filter, or blown outside if permissable.
-Cut quality is best with a downdraft table.
-The air flow for a 4 x 4 table is typically 3000cfm to 5000cfm to completely remove fumes
-No freeze problem, but when the blower is blowing outside....heat is also being removed from shop.
-No water staining, better edge smoothness, minimal dross formation.
I have one table with a downdraft and one with a water table. I prefer the downdraft for cut quality and stain rust issues.
Jim Colt Hypertherm
BXpanded
Silver Member, Approved Advertiser
Add some Sodium Nitrite to the water table to help inhibit rust. Note: Sodium Nitrite, not Sodium Nitrate.
crazyal
Super Member
Jim, have you thought about offering an economy line of plasma cutters, maybe using an older generation of tech, something for the weekend warrior who can't afford a machine that's designed for daily shop use? I'm not even sure if it's possible. Something basic that's not too much more than what's coming out of China but would offer the owner to possibly upgrade in the future to a nicer torch or consumables. Sorry if this is a little off topic.
Shield Arc
Super Member
Really! I don't think I've ever heard of this. Please tell us more! I've cut a little aluminum, but not a whole lot. I can't remember if I cut over water or not, I think I did:confused2:. I looked through my pictures, this one is cutting over the tank, but looks like the tank is empty.
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jimcolt
Gold Member
Hypertherm has a full line of plasma systems from our 30 amp air plasma to our 800 amp industrial high definition class plasma. It has always been our corporate philosophy to lead the thermal plate cutting market with technology and reliability that is superior to all other's that compete. Hypertherm has over 95 professional engineers (out of 1300 employees), 15 of those engineers have pHd's in various areas of expertise. We are kind of flattered by the level of duplication (copying!) that we see from pretty much all of our competitors after new technology and patents that we posses have run their course. Many of the torches that you see on import plasma systems today are copies of older Hypertherm technology from 20 to 30 years ago.....designs that we abandoned in favor of new tech breakthroughs that affect cut quality, cut speed and consumable life (cost of operation).
That being said, Hypertherm does have a big investment in its technology, and while we likely could design and build a system or two that could compete on a cost basis with the imports.....we know that we would have to take a step or two backwards with our current systems performance to do so...and so far we are not willing to do that.
The expenses involved in a plasma system involve the power supply design....having the correct voltage / amperage curve to maintain arc voltage and amps when cutting thick materials....without overheating internal components (electronic swtching devices, transformer, etc) as well as careful coordination of current, air flow at the beginning and end of a cut....which dramatically increases consumable life. So design/engineering time, manufacturing labor, and component costs all add up. When you copy as much as you can (save on engineering) and use the lowest cost components (lower duty cycle, reliability) and use low cost labor from somewhere other than the U.S.....you have an advantage in cost, but not performance.
I totally agree that there is a good market for low cost plasma systems....in my early metal fab days I would have bought one...because purchase price was more important to me than reliability or long term operating cost (consumable usage).
The nice alternative today....air plasma systems have become so popular that there are many, many used major brand name (Hypertherm, Thermal Dynamics, Miller, Esab to name a few) units in the field.....and there is Ebay and Craigslist. Every day I see a good used Hypertherm on Craigslist that sells for a price similar to the cheap imports. Also....the smallest Hypertherm system, the Powermax30, is a little powerhouse that packs as much power as most 50 amp imports.....and still sells in the $1000 range.
Sorry for the long explanation about low cost vs major brand plasma!
Jim Colt
That being said, Hypertherm does have a big investment in its technology, and while we likely could design and build a system or two that could compete on a cost basis with the imports.....we know that we would have to take a step or two backwards with our current systems performance to do so...and so far we are not willing to do that.
The expenses involved in a plasma system involve the power supply design....having the correct voltage / amperage curve to maintain arc voltage and amps when cutting thick materials....without overheating internal components (electronic swtching devices, transformer, etc) as well as careful coordination of current, air flow at the beginning and end of a cut....which dramatically increases consumable life. So design/engineering time, manufacturing labor, and component costs all add up. When you copy as much as you can (save on engineering) and use the lowest cost components (lower duty cycle, reliability) and use low cost labor from somewhere other than the U.S.....you have an advantage in cost, but not performance.
I totally agree that there is a good market for low cost plasma systems....in my early metal fab days I would have bought one...because purchase price was more important to me than reliability or long term operating cost (consumable usage).
The nice alternative today....air plasma systems have become so popular that there are many, many used major brand name (Hypertherm, Thermal Dynamics, Miller, Esab to name a few) units in the field.....and there is Ebay and Craigslist. Every day I see a good used Hypertherm on Craigslist that sells for a price similar to the cheap imports. Also....the smallest Hypertherm system, the Powermax30, is a little powerhouse that packs as much power as most 50 amp imports.....and still sells in the $1000 range.
Sorry for the long explanation about low cost vs major brand plasma!
Jim Colt
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What about just making one of your older models again. Still would be better then some imports, but could cost a lot less.
jimcolt
Gold Member
In my 35 years of experience with large industrial shops as well as small fab shops....there have only ever been one or two issues with cutting of aluminum over a water table. This myth has grown way out of proportion to the facts!
When you cut aluminum over water (water is commonly used to trap and control smoke and fumes from the plasma cutting process) the ejected molten material from the plate is blow down into the water where it cools and solidifies. This material mostly consists of aluminum oxide particles....these particles tend to absorb oxygen, and water (H20) is comprised of oxygen and hydrogen. When you remove oxygen from water....a small amount of hydrogen is left over.....which rises in the water bed (table) to the top....the disipates in the air. Even in large industrial applications that cut hundreds of tons of aluminum daily....this small amount of hydrogen is generally not a problem.
If the water table is of a design that has brackets or framing that allows some of the rising hydrogen bubbles to become trapped.....over time a rather large pocket of hydrogen could collect....and with a spark...certainly could produce an explosion. Another scenario is that you cut aluminum all morning in a busy shop, load a new 5 x 10 sheet that happes to be bowed up a bit in the center....then go to lunch. While at lunch the aluminum oxide particles from the morning's work are releasing hydrogen bubbles....which rise and become trapped under the plate......return from lunch and fire the torch..and you can have a hydrogen explosion (usually however it is more like the "pop" of a firecracker!)
Most industrial water table manufacturers build their tables so that rising bubbles cannot be trapped.....also build he tables with aerator pipes (pipes with many holes with compressed air) and allow air to rise in the water...diluting any hydrogen that could become trapped under the plate.
Small entry level cutting tables or hand cutting generally cannot cut enough aluminum to cause an explosion issue!
Best regards, Jim Colt Hypertherm
When you cut aluminum over water (water is commonly used to trap and control smoke and fumes from the plasma cutting process) the ejected molten material from the plate is blow down into the water where it cools and solidifies. This material mostly consists of aluminum oxide particles....these particles tend to absorb oxygen, and water (H20) is comprised of oxygen and hydrogen. When you remove oxygen from water....a small amount of hydrogen is left over.....which rises in the water bed (table) to the top....the disipates in the air. Even in large industrial applications that cut hundreds of tons of aluminum daily....this small amount of hydrogen is generally not a problem.
If the water table is of a design that has brackets or framing that allows some of the rising hydrogen bubbles to become trapped.....over time a rather large pocket of hydrogen could collect....and with a spark...certainly could produce an explosion. Another scenario is that you cut aluminum all morning in a busy shop, load a new 5 x 10 sheet that happes to be bowed up a bit in the center....then go to lunch. While at lunch the aluminum oxide particles from the morning's work are releasing hydrogen bubbles....which rise and become trapped under the plate......return from lunch and fire the torch..and you can have a hydrogen explosion (usually however it is more like the "pop" of a firecracker!)
Most industrial water table manufacturers build their tables so that rising bubbles cannot be trapped.....also build he tables with aerator pipes (pipes with many holes with compressed air) and allow air to rise in the water...diluting any hydrogen that could become trapped under the plate.
Small entry level cutting tables or hand cutting generally cannot cut enough aluminum to cause an explosion issue!
Best regards, Jim Colt Hypertherm
jimcolt
Gold Member
Actually it would cost us more to "build again" one of our older models. Our new models are designed with better technology as well as to be less labor intensive on the production floor.
Better technology means lower warranty cost....so older models would cost more after warranty costs are added in. Newer models are designed with more efficient manufacturing in mind as well...remember we pay reasonable U.S. wages to our assembly personel....many imports are built with incredibly low paid workers. The average man hours to build the older technology products are much higher that the newer designs.
Trust me....there are no near future plans for a plasma system from Hypertherm that will compete on purchase price vs asian built imports. From a cost point of view it likely cannot be done, and from a performance point of view it is not within our corporate philosphy to take a step backwards.
Hypertherm is employee owned....these decisions are made by the employees....not by an overpaid director that is only interested in the bottom line.
Jim
Better technology means lower warranty cost....so older models would cost more after warranty costs are added in. Newer models are designed with more efficient manufacturing in mind as well...remember we pay reasonable U.S. wages to our assembly personel....many imports are built with incredibly low paid workers. The average man hours to build the older technology products are much higher that the newer designs.
Trust me....there are no near future plans for a plasma system from Hypertherm that will compete on purchase price vs asian built imports. From a cost point of view it likely cannot be done, and from a performance point of view it is not within our corporate philosphy to take a step backwards.
Hypertherm is employee owned....these decisions are made by the employees....not by an overpaid director that is only interested in the bottom line.
Jim
