Are you suggesting the video is played back at fast speed? If that's what you're saying, and if you're correct, then it would mean that the ON pulse is well above 125-200mS. Maybe half a second.

This is what I was talking about when I made the suggestion to just use reasonable numbers and make something that works, then make outrageous and obviously false claims about its performance. That's how China do.

Thanks.
I should first explain that the ' (10^-6)' kind of stuff in my first post is from a theoretical definition of cold welding machine [CWM.].
NOT for any selling cold welding machine or even any component。
I am not sure, I don't think the video about CWM. on Youtube did accelerated.

I agree with you that 'just use reasonable numbers and make something that works', it is exactly what I am looking for.

 

If this is going to continue we should start to call it by it's real name/term. While Laoadam is calling it "cold welding" that is a marketing name. The real name is "pulse TIG welding". And he will get more information if that is the name he searches for, instead of cold welding.

Here is a link to a company that is the supposed gold standard(by many that use them) of pulse tig machines -
https://sunstonewelders.com/orion-jewelry-welder. There are a few others making them but people that are serious usually end up with one of their machines as their work gets more intense and start to make money at it. Click one the resources button at the top of the page to get more info on the processes. But be prepared when looking at the prices of the machines unless the price has gone down since I looked.

There are less expensive ones if you just want to look into it to see if it will do what you want. These are just a few links to the less expensive machines, a Google for "jewelry spot welder" gets more. One of these in my opinion would, at the price be much better and do more than trying to DIY one, since there is so little information on doing it that way. And you get all of the welding hardware with most of them. And don't forget you will need an argon tank which is fairly expensive to buy.

https://www.gesswein.com/p-13745-pu...kv66_UPRUTSuS87jWCQy0J4gdWvPsgzBoCP5QQAvD_BwE

https://www.ebay.com/itm/1532990483...yLx74PLlbfm80_lH191Q6LmIPzBickkxoCr6MQAvD_BwE

https://www.amazon.com/Carejoy-Spar...ocphy=9015438&hvtargid=pla-944548195365&psc=1

Thanks.
lot helpful.
There is too much to talk the difference between 'cold welding' and 'pulse TIG welding' here now.
Please let's make thing simple: how to turn on/turn off a SCR/MOSFET/IGBT in about 200A in whatever time interval but controllable for now?

 

There is too much to talk the difference between 'cold welding' and 'pulse TIG welding'

Well you may think that but go back to your original video in the first post. What do you see? I see a ceramic tig welding cup and a tungsten tig electrode. So call it what ever you want.

Please let's make thing simple: how to turn on/turn off a SCR/MOSFET/IGBT

Not trying to be cruel or nasty, but if you have to ask that question, you are in over your head. Good luck.

 

Well you may think that but go back to your original video in the first post. What do you see? I see a ceramic tig welding cup and a tungsten tig electrode. So call it what ever you want.



Not trying to be cruel or nasty, but if you have to ask that question, you are in over your head. Good luck.

Thanks.
Its true the 'cold welding machine' is very approximately same as TIG, actually there are many CWMs converted from TIG on marketer. they are different principle.

'trying to be cruel or nasty'? No. I just like to have this talking simple and useful.

 

Thanks.
lot helpful.
There is too much to talk the difference between 'cold welding' and 'pulse TIG welding' here now.
Please let's make thing simple: how to turn on/turn off a SCR/MOSFET/IGBT in about 200A in whatever time interval but controllable for now?

Well several members here more knowledgeable than myself have suggested SCR as the discharge device so I would be inclined to start there, but as I understand it you are opposed to that because it does not meet your criteria of "controllable" because it can't be turned off in a certain time.

To address that, GTO thyristors were suggested. This is (my understanding) a special type of SCR that you can turn off. I know little about GTOs as I have never seen one. They were recommended to me some years ago for a project and sounded promising, but I was unable to find any that matched my needs. In fact if memory serves, I was hardly able to find any GTOs for sale off the shelf at all, much less anywhere even close to my specs. From that experience I gained the impression that these are unobtainable for hobby projects and that they are usually custom ordered in large quantities to customer specifications. I have never looked into them since then. It is possible I just didn't look in the right places, or my memory is bad. If some links can be provided for GTOs that would work, then that is probably what I would recommend.

But failing that, I would stick to what I know. MOSFETS or IGBTs. Probably MOSFETs, because they are more easily used in parallel since they have a negative temperature coefficient. You can use 10 cheap little MOSFETs in place of one big one. I would use a microcontroller to control pulse width and timing because again, that's what I know. I would want something where I can easily adjust the timing values to play around and experiment to find the right times. Some others here could probably provide a simple 555/potentiometer circuit to achieve the same goal, or you could Google something for it. It would probably be easier for you if you have no microcontroller experience.

If I were you, I would research the following and then you will have a better picture of the path to success:
TIG high frequency start circuits
MOSFET high side driver circuits
555 timer & wave generator circuits
Parallel MOSFET circuits
MOSFET Gate ringing

 

Using the correct words will have a much better chance of providing the intended meanings to be conveyed, and that is usually important. And for product descriptions it can be very VERY important. Assuring that the correct words are used and that there is only one possible meaning provided was one portion of my responsibility in creating sales letters, which were the document that described exactly what our customer was, and was not, getting for their money.
Really, "cold welding" would describe the compression bonding used to attach wires to the dies in integrated circuits and some transistors, at one stage of the technology development. That is very different from impulse welding, either with or without the protective gas shield. Those are hot welds, although the HAZ, Heat Affected Zone, may be very small. Shortbus can provide a more detailed explanation than I can about that.

 

Well several members here more knowledgeable than myself have suggested SCR as the discharge device so I would be inclined to start there, but as I understand it you are opposed to that because it does not meet your criteria of "controllable" because it can't be turned off in a certain time.

To address that, GTO thyristors were suggested. This is (my understanding) a special type of SCR that you can turn off. I know little about GTOs as I have never seen one. They were recommended to me some years ago for a project and sounded promising, but I was unable to find any that matched my needs. In fact if memory serves, I was hardly able to find any GTOs for sale off the shelf at all, much less anywhere even close to my specs. From that experience I gained the impression that these are unobtainable for hobby projects and that they are usually custom ordered in large quantities to customer specifications. I have never looked into them since then. It is possible I just didn't look in the right places, or my memory is bad. If some links can be provided for GTOs that would work, then that is probably what I would recommend.

But failing that, I would stick to what I know. MOSFETS or IGBTs. Probably MOSFETs, because they are more easily used in parallel since they have a negative temperature coefficient. You can use 10 cheap little MOSFETs in place of one big one. I would use a microcontroller to control pulse width and timing because again, that's what I know. I would want something where I can easily adjust the timing values to play around and experiment to find the right times. Some others here could probably provide a simple 555/potentiometer circuit to achieve the same goal, or you could Google something for it. It would probably be easier for you if you have no microcontroller experience.

If I were you, I would research the following and then you will have a better picture of the path to success:
TIG high frequency start circuits
MOSFET high side driver circuits
555 timer & wave generator circuits
Parallel MOSFET circuits
MOSFET Gate ringing

Thank you for so detail.

Firstly, I would say I am not to insist on some one kind of component. I ordered SCR right after I got the suggestion. I was planed try to use MOSFET or IGBT only because I have them in hand.

I gonna order GTO today as mentioned.

Thanks again for the keywords.

 

Using the correct words will have a much better chance of providing the intended meanings to be conveyed, and that is usually important. And for product descriptions it can be very VERY important. Assuring that the correct words are used and that there is only one possible meaning provided was one portion of my responsibility in creating sales letters, which were the document that described exactly what our customer was, and was not, getting for their money.
Really, "cold welding" would describe the compression bonding used to attach wires to the dies in integrated circuits and some transistors, at one stage of the technology development. That is very different from impulse welding, either with or without the protective gas shield. Those are hot welds, although the HAZ, Heat Affected Zone, may be very small. Shortbus can provide a more detailed explanation than I can about that.

Thanks.
Some where mentioned that the 'CWMs' is simply just a DC power supply shorted by controlled turn on/off at curtain frequency?

 

One other feature of a SCR/Capacitive discharge welder is that the welding point device maintains a certain pressure which Must be met before the Discharge is permitted.
Just as a spot welder does.

 

One other feature of a SCR/Capacitive discharge welder is that the welding point device maintains a certain pressure which Must be met before the Discharge is permitted.
Just as a spot welder does.

I think this is a different thing than the pulsed tig from the video? The tig electrode makes no contact with the base or filler metal. It requires a HF start circuit or "pilot" to create a plasma arc through air, through which the welding current then passes, per my understanding.

 

Yes, agree, this is why I stressed the requirement if using a SCR discharge method.

 

Actually, non-contact TIG welding is rather complex to control, Wire-feed MIG welding with an automatic machine is far easier, but it also requires a more complex control setup.

 

Yes, agree, this is why I stressed the requirement if using a SCR discharge method.

Oh, sorry I got mixed up with who said what and maybe I was confused about even more than that. I had the impression that the consensus was SCRs are best. I thought you were stressing to use them, as opposed to stressing the need for pressure if you use them.

 

Oh, sorry I got mixed up with who said what and maybe I was confused about even more than that. I had the impression that the consensus was SCRs are best. I thought you were stressing to use them, as opposed to stressing the need for pressure if you use them.

Thanks and no worry.
We are discuss and any post is helpful.

 

One other feature of a SCR/Capacitive discharge welder is that the welding point device maintains a certain pressure which Must be met before the Discharge is permitted.
Just as a usual welder does.

It's a true. But probably I'm the last dinosaur who will prefer to use usual 120/240V welder in every work case...

 

It's a true. But probably I'm the last dinosaur who will prefer to use usual 120/240V welder in every work case...

There are a FEW folks who are very good at regular AC stick welding. Their work is amazing to see.
I am NOT one of those folks. I can do an adequate weld with a properly adjusted wire-feed-inert gas-shielded welder, that is my welding skill level. But I solder quite well.

 

Actually, non-contact TIG welding is rather complex to control, Wire-feed MIG welding with an automatic machine is far easier, but it also requires a more complex control setup.

Explain that statement farther, it makes no sense at all to someone that owns welders and is good at all types of welding.

 

Explain that statement farther, it makes no sense at all to someone that owns welders and is good at all types of welding.

OK, the person who I watched doing TIG welding had the electrode for the spark in one hand and the welding rod in his other hand and he would strike the arc and then move it along as he fed the filler rod in with the other hand. That requires some good coordination to keep the arc the correct distance while moving and feeding the filler rod with the other hand. With the MIG wire feed welder that I used all I had to do was bring the weld gun up and when the arc struck the gas came on and the wire feed started at the correct speed for how fast I was moving. I might have had to push a button, I don't recall. But certainly I was able to produce an adequate weld after only some brief instructions. The TIG process certainly required a great deal more skill to do as good a job. So I think that the controls for the TIG welder had to include some system for starting the arc without touching, and starting the gas. That is more complex.

 

With the MIG wire feed welder that I used all I had to do was bring the weld gun up and when the arc struck the gas came on and the wire feed started at the correct speed for how fast I was moving. I might have had to push a button,

That is the basis for most automatic (no operator) MIG welding M/C's although the wire feed and gas comes on as soon as the initiation process starts automatically, and the weld starts as soon as the wire contacts the work pieces.

 

OK, the person who I watched doing TIG welding had the electrode for the spark in one hand and the welding rod in his other hand and he would strike the arc and then move it along as he fed the filler rod in with the other hand. That requires some good coordination to keep the arc the correct distance while moving and feeding the filler rod with the other hand. With the MIG wire feed welder that I used all I had to do was bring the weld gun up and when the arc struck the gas came on and the wire feed started at the correct speed for how fast I was moving. I might have had to push a button, I don't recall. But certainly I was able to produce an adequate weld after only some brief instructions. The TIG process certainly required a great deal more skill to do as good a job. So I think that the controls for the TIG welder had to include some system for starting the arc without touching, and starting the gas. That is more complex.

You could be right about MIG if someone set the parameters for you ahead of time. But there is a big difference in an "adequate weld" and a structurally sound weld. Tig welds need the same type of settings that are done on a Mig machine, the big difference is the operator decides when and how much filler is added.