The top three photos was taken when I just started playing with the pulses on the pulse arc welder. The top left photo is two washers welded together, the middle is two strands from a 12 gauge copper wire welded to a washer and the photo on the right is two strands of a 12 gauge wire that were held against the tungsten electrode while firing a 45ms pulse. The bottom two photos were taken after I managed to manipulate and change the pulses to give better welds. The plasma flame produced here is extremely hot.
I have made thousands of welds and adjustments to get this far and will keep on going until I get it to work perfectly. I accidentally made a plasma cutter that cuts through metal when I made the pulses continuous and also managed to weld a copper wire to aluminum.
I'm limited to the metals I have to do further tests however and will appreciate if someone with knowledge of these welders can help me with some advice. Email me at sprbok@gmail.com
Very nice work Fritz! This board will make a great addition to an already terrific spot welder.
ReplyDeleteAgreed! Truly an awesome addition to the welder.
ReplyDeleteSome of the Orion Jewellery videos may provide some insight, although I'm sure you've looked at these. I'm not sure how complex pulse programs need to be, providing that the end user is given the ability to adjust power and duration of arc (via solenoid pulses).
Some pulse arc comments here:
"Pulse arc rates can be adjusted from 1 to over 100 pulses per second, and with some equipment, to over 1000 pulses per second. When a programmed weld is made involving current upslope and downslope, pulsation starts at the beginning of upslope where both the peak and the background current increase to the beginning of main weld current and continue to pulse at those values for the remainder of weld time. Both peak and background current start to diminish to a final current at the end of the downslope time. This type of weld program is often used for girth welding pipe or tubing."
See http://www.welding-robots.com/applications.php?app=pulsed+arc+welding
By the way, what type of solenoid do you have inside the pulse arc welding stylus? I wonder what the response time limit is for this solenoid? This would likely determine the constraints of how the plasma arc is sustained.
ReplyDeletehttp://frikkieg.blogspot.com/2010_09_01_archive.html
Ogi, thanks for the info. I would like to know how the pulse looks like, are they triangle, sinus or square waves. I know that Orion uses the discharge of the capacitors to cool the welds and prevent them from cracking. I am doing the same with pulse width control. Sinus waves are for aluminum but I'm very sure that the Orion does not use sinus waves.
ReplyDeleteI am not calculating the speed of the solenoid because it is very inaccurate. A solenoid will always be too fast or too slow. The timing here is crucial, to fast and the electrode will burn and get stuck to the work piece, too slow and you will not get a weld.
I basically calculates the resistance between the electrode and the work piece with the processor and fires at an exact same time within 10uS just before the electrode pulls away from the metal. I get a good plasma arc throughout the weld.
They are talking about droplets and "the pinch off of the pulse" I would like to know how the pinch off of the pulse looks like and when do you get the pray effect, is it at a certain frequency?
I found some good info here http://content.lincolnelectric.com/pdfs/products/literature/nx270.pdf
ReplyDeleteThe following is from the ESABNA web site, which does not specifically cover CD welding. Where they mention spray arc applications, they refer to "metal being transferred to the work" meaning that a wire filler is being fed into the weld. However, general pulse arc energy details still apply.
ReplyDelete"A variation of this spray arc technique is known as ”pulsed” spray welding. In pulsed spray arc welding, the current is varied between a high and low value. The low level of current is below the transition current while the high level is well into the spray arc region. Metal is only transferred to the work during the period of high current. Usually one droplet is transferred during each high current pulse."
See http://www.esabna.com/euweb/mig_handbook/migpg8dia.jpg
The image depicts the welding current pattern used in pulsed spray arc welding. In the United States, only 60 or 120 pulses per second are used. Because the peak current is in the spray arc region, arc stability is similar to that of conventional spray arc welding. The period of low current maintains the arc and serves to reduce the average current. Thus, the pulse spray technique will produce a spray arc at lower average current levels than are required for conventional spray arc welding. The lower average current makes it possible to weld thinner gauge materials with spray type transfer using larger sized wire electrodes than otherwise possible. Pulsed spray arc welding can also be used for out-of-position welding of heavier sections."
Above excerpt from http://www.esabna.com/euweb/mig_handbook/592mig1_8.htm
Also compare the thermal properties of base metals: http://www.ogilumen.com/images/custom/metals.jpg
There is a document discussing the waveform characteristics demonstrated by the Orion welders:
"Because the Orion is based on a capacitive discharge resistance welder the welding output pulse will have a smooth welding current decay. The pulse will start with a peak current which will decay to a final weld current value. The curve will look very similar to a triangle. If the weld pulse is allowed to decay fully to its low state the actual weld will look smooth. This decay behaviour allows the weld pool to solidify more slowly and provides an extremely fine, smooth finish. If the weld pulse (and time) are short the pulse will approximate a square shape. The weld current will rise quickly and stay relatively constant and then stop. This type of square pulse behaviour is an excellent choice when the weld electrode must be placed at a shallow angle. The square pulse (short weld time) provides a stable arc as the weld electrode is retracted."
It further mentions details about electrode diameters:
"The Orion pulse arc welding stylus can accept two electrode diameters, 0.5mm and 1.0mm. Weld current is related to the diameter of the welding electrode. For small, low power welds, use 0.5mm electrodes. For welds all the way from the low to high power, the 1.0mm electrode is preferred."
See http://www.docstoc.com/docs/24684099/Welding-Basics-The-Orion-is-a-true-micro-pulse-arc-welder-It-is
http://www.ogilumen.com/images/custom/decay.jpg
The following is from the ESABNA web site, which does not specifically cover CD welding. Where they mention spray arc applications, they refer to "metal being transferred to the work" meaning that a wire filler is being fed into the weld. However, general pulse arc energy details still apply.
ReplyDelete"A variation of this spray arc technique is known as ”pulsed” spray welding. In pulsed spray arc welding, the current is varied between a high and low value. The low level of current is below the transition current while the high level is well into the spray arc region. Metal is only transferred to the work during the period of high current. Usually one droplet is transferred during each high current pulse."
See http://www.esabna.com/euweb/mig_handbook/migpg8dia.jpg
The image depicts the welding current pattern used in pulsed spray arc welding. In the United States, only 60 or 120 pulses per second are used. Because the peak current is in the spray arc region, arc stability is similar to that of conventional spray arc welding. The period of low current maintains the arc and serves to reduce the average current. Thus, the pulse spray technique will produce a spray arc at lower average current levels than are required for conventional spray arc welding. The lower average current makes it possible to weld thinner gauge materials with spray type transfer using larger sized wire electrodes than otherwise possible. Pulsed spray arc welding can also be used for out-of-position welding of heavier sections."
Above excerpt from http://www.esabna.com/euweb/mig_handbook/592mig1_8.htm
Also compare the thermal properties of base metals: http://www.ogilumen.com/images/custom/metals.jpg
There is a document discussing the waveform characteristics demonstrated by the Orion welders:
"Because the Orion is based on a capacitive discharge resistance welder the welding output pulse will have a smooth welding current decay. The pulse will start with a peak current which will decay to a final weld current value. The curve will look very similar to a triangle. If the weld pulse is allowed to decay fully to its low state the actual weld will look smooth. This decay behaviour allows the weld pool to solidify more slowly and provides an extremely fine, smooth finish. If the weld pulse (and time) are short the pulse will approximate a square shape. The weld current will rise quickly and stay relatively constant and then stop. This type of square pulse behaviour is an excellent choice when the weld electrode must be placed at a shallow angle. The square pulse (short weld time) provides a stable arc as the weld electrode is retracted."
It further mentions details about electrode diameters:
"The Orion pulse arc welding stylus can accept two electrode diameters, 0.5mm and 1.0mm. Weld current is related to the diameter of the welding electrode. For small, low power welds, use 0.5mm electrodes. For welds all the way from the low to high power, the 1.0mm electrode is preferred."
See http://www.docstoc.com/docs/24684099/Welding-Basics-The-Orion-is-a-true-micro-pulse-arc-welder-It-is
http://www.ogilumen.com/images/custom/decay.jpg
The following is from the ESABNA web site, which does not specifically cover CD welding. Where they mention spray arc applications, they refer to "metal being transferred to the work" meaning that a wire filler is being fed into the weld. However, general pulse arc energy details still apply.
ReplyDelete"A variation of this spray arc technique is known as ”pulsed” spray welding. In pulsed spray arc welding, the current is varied between a high and low value. The low level of current is below the transition current while the high level is well into the spray arc region. Metal is only transferred to the work during the period of high current. Usually one droplet is transferred during each high current pulse."
See http://www.esabna.com/euweb/mig_handbook/migpg8dia.jpg
The image depicts the welding current pattern used in pulsed spray arc welding. In the United States, only 60 or 120 pulses per second are used. Because the peak current is in the spray arc region, arc stability is similar to that of conventional spray arc welding. The period of low current maintains the arc and serves to reduce the average current. Thus, the pulse spray technique will produce a spray arc at lower average current levels than are required for conventional spray arc welding. The lower average current makes it possible to weld thinner gauge materials with spray type transfer using larger sized wire electrodes than otherwise possible. Pulsed spray arc welding can also be used for out-of-position welding of heavier sections."
Above excerpt from http://www.esabna.com/euweb/mig_handbook/592mig1_8.htm
Also compare the thermal properties of base metals: http://www.ogilumen.com/images/custom/metals.jpg
There is a document discussing the waveform characteristics demonstrated by the Orion welders:
ReplyDelete"Because the Orion is based on a capacitive discharge resistance welder the welding output pulse will have a smooth welding current decay. The pulse will start with a peak current which will decay to a final weld current value. The curve will look very similar to a triangle. If the weld pulse is allowed to decay fully to its low state the actual weld will look smooth. This decay behaviour allows the weld pool to solidify more slowly and provides an extremely fine, smooth finish. If the weld pulse (and time) are short the pulse will approximate a square shape. The weld current will rise quickly and stay relatively constant and then stop. This type of square pulse behaviour is an excellent choice when the weld electrode must be placed at a shallow angle. The square pulse (short weld time) provides a stable arc as the weld electrode is retracted."
It further mentions details about electrode diameters:
"The Orion pulse arc welding stylus can accept two electrode diameters, 0.5mm and 1.0mm. Weld current is related to the diameter of the welding electrode. For small, low power welds, use 0.5mm electrodes. For welds all the way from the low to high power, the 1.0mm electrode is preferred."
See http://www.docstoc.com/docs/24684099/Welding-Basics-The-Orion-is-a-true-micro-pulse-arc-welder-It-is
http://www.ogilumen.com/images/custom/decay.jpg
The following is from the ESABNA web site, which does not specifically cover CD welding. Where they mention spray arc applications, they refer to "metal being transferred to the work" meaning that a wire filler is being fed into the weld. However, general pulse arc energy details still apply.
ReplyDelete"A variation of this spray arc technique is known as ”pulsed” spray welding. In pulsed spray arc welding, the current is varied between a high and low value. The low level of current is below the transition current while the high level is well into the spray arc region. Metal is only transferred to the work during the period of high current. Usually one droplet is transferred during each high current pulse."
See http://www.esabna.com/euweb/mig_handbook/migpg8dia.jpg
The image depicts the welding current pattern used in pulsed spray arc welding. In the United States, only 60 or 120 pulses per second are used. Because the peak current is in the spray arc region, arc stability is similar to that of conventional spray arc welding. The period of low current maintains the arc and serves to reduce the average current. Thus, the pulse spray technique will produce a spray arc at lower average current levels than are required for conventional spray arc welding. The lower average current makes it possible to weld thinner gauge materials with spray type transfer using larger sized wire electrodes than otherwise possible. Pulsed spray arc welding can also be used for out-of-position welding of heavier sections."
Above excerpt from http://www.esabna.com/euweb/mig_handbook/592mig1_8.htm
Also compare the thermal properties of base metals: http://www.ogilumen.com/images/custom/metals.jpg
This wiki document has a few added details about detecting the "pinch" event, and relates the STT of the PDF you've found:
ReplyDeleteThere are proprietary derivatives of the short-circuiting transfer mode which use a modified waveform to reduce some of the problems found with short-circuiting, mainly spatter and a turbulent weld pool. Typically these systems sense the progression of the short circuit as it happens and modulate the current to limit the amount of force behind spatter and turbulence-producing events. Several manufacturers now sell welding power supplies which employ technology to this end: Miller Electric has a process called Regulated Metal Deposition (RMD), while Lincoln Electric sells their process called Surface Tension Transfer (STT). Other companies take a different approach to making short circuit transfer usable: Fronius has a technique called Cold Metal Transfer (CMT) which physically withdraws the electrode from the welding puddle at a certain rate and pattern.
RMD and STT achieve the modified short circuiting via software that controls the current.
The RMD process breaks the process into seven steps:
Wet: Let the ball on the end of the wire wet-out to the puddle.
Pinch: Increase the current to a level high enough to initiate a pinch effect.
Clear: Maintain and slightly increase the pinch current to clear the short circuit while simultaneously watching for pinch detection.
Blink: Upon pinch detection, rapidly decrease the current. Pinch detection occurs before the short clears. The inverter “shuts off” and current decays to a low level before the short circuit breaks.
Ball: Increase current to form a ball for the next short circuit.
Background: Drop the current to a low enough level to allow a short circuit to occur.
Pre-short: If the background current exists for a relatively long time, the pre-short period drops current to an even lower level to make sure arc force does not produce excessive puddle agitation.
See http://en.wikipedia.org/wiki/Gas_metal_arc_welding
Among the RMD/STT/CMD protocols, there are some interesting options.
ReplyDeleteSome CMD information is posted here:
http://www.fronius.com/cps/rde/xchg/fronius_international/hs.xsl/79_9399_ENG_HTML.htm
and here:
http://www.youtube.com/watch?v=_WrhWf9XLHM
Thanks Ogi, I have read through your recommended sites and have a better understanding about TIG welding and how the melted drops get transferred to the metal with every pulse.
ReplyDeleteJust curious, do you play with the size of the cable connected to your stylus? That will limit current that can flow to stylus and perhaps will make the weld neater?
ReplyDeleteIs it possible that we can use the high voltage (such as those battery powered device that lit up stove in kitchen) to bridge the air and make it conduct, then we turn on the MOSFET of control discharge of capacitor (with a 200A 1kV? rectifier in series, as high voltage can kill MOSFET if not isolate it? (I don't know how long a MOSFET can sustain under high Voltage) 200A is enough as I think TIG required only less current than spot welder)
In this way not need to draw the tungsten back? just have to keep it at a near distance to working surface.
Just some opinions, hope you don't mind if this is just some stupid idea.
David
David, yes, I can easily make a high voltage start circuit for this welder but it will take the "micro pulse" out of this welder and make it a TIG welder. High voltage circuits will shock and you will probably get a nasty shock when starting your plasma flame up. The price of jewelry would go up and all Jewelers would be easily identified as the guys with the big eyes and the Einstein looking hair:))
ReplyDeleteHave you had any success in duplicating the Lincoln welder pulse arc waveform profiles?
ReplyDeleteOgi, not yet, I'm thinking of replacing the mosfet board with a new IGBT board and build a complete pulse arc welder without adding it to the tab welder. Money and time is holding me back at the moment and It will take some time to get it done though. Thanks for your help so far.
ReplyDeleteThe IGBT sounds like the best option for the pulse arc welds. Adding the solenoid control and argon might not have fit into the everyone's tab welder cabinets. http://www.ogilumen.com/images/custom/argon.jpg
ReplyDeletei can send you over some more igbt's if needed.
ReplyDeletein this way you have the option of aliminium and other alloy wielding as dc weakens the metal by mucking with the alignment of the electrons or something (so im told)
ac voltages to the electrodes is another benifit if you used a hbribge igbt.
there is an arc start circuit in this project that may be of intrest?
may be helpfull has some good info and could be chopped up and a microprocessor slaped in place of the ttl logic.
http://www3.telus.net/public/a5a26316/TIG_Welder.html
Jonny, as far as I know, tig welders use pulsed dc to weld most metals and only use ac for metals like silver and aluminum. The reason is that the alternating voltage basically gives the metal a time to cool down between cycles and the polarity that changes cleans the tungsten electrode. I don't think the PUK and the Orion uses alternating current. The pulse arc on this welder will have a negative electrode and the work piece will be positive. This will prevent electrode contamination and by making the off time of the pulse a little longer can give the cool down effect that alternating current does. The PUK also uses sawtooth waveforms( I don't know for what yet but I'll try and figure it out.
ReplyDeleteAC will just cost more, you can build the same circuit as the one you suggested, with pulsed DC, using 1/4 of the IGBT's or use them in parallel to give much higher currents.
You know my toolbox always need more IGBT's and the ones you sent me before are going to get used, thanks Jonny
what i am told the ac is to eliminate deposits building up on either the weled part or tips of the torch and to aviod electron depletion in the part causing weakness around where the part is earthed or welded.
ReplyDeleteheating was a reason also but not the primary reason
they use a aprox 200hz frequency ac saw tooth for wielding aliminium pulsed dc can be used but is not recomended for brass or ali because of electron depletion this is what i am told.
i have a welding engineer i can ask if you do have any questions like this.
the frequency is so you dont have to torch so close for some reason helps the arc to be more stable.
From what it looks like, you basically have a small TIG welder. Are you using HF to start the arc? I'm currently trying to build an HF generator. Maybe I can help you out somehow?
ReplyDelete