EB beam current fluctuation problem

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HiI am new to the forum,sorry for any mistake.We have PTR EBW machine.we try to weld tungsten block,we set the beam current to 4.3mA,the welding process goes fine when suddenly there is a change in beam current and as a result in beam also,and the beam current display shows around 5mA,what can be be the possible causes in beam current and the beam?.Thanks
Reply:Anwar,Welcome to the forum.   Unfortunetly I've got to tell you that answering your question is probably way out side the expertise of any one here (that I know of).   I think your best option is to try and get some factory support from the people that built your EBW set up.
Reply:Has the arc length of your beam changed?  I assume this is robotic and not hand held.  A bad spot in the track?  Feed rate change?  A bad spot in a servo. Is air pressure involved?  Is it stable?Can you tell us more about the procedure. Who sold you the process?  Have you consulted them?Dan D.Manipulator Of Metal
Reply:DanD,You might find this informative about EBW.    http://www.ptreb.com/Electron_Beam_W...and_Equipment/
Reply:Originally Posted by HT2-4956Anwar,Welcome to the forum.   Unfortunetly I've got to tell you that answering your question is probably way out side the expertise of any one here (that I know of).   I think your best option is to try and get some factory support from the people that built your EBW set up.
Reply:Thanks for link HT. I will look it over later.  Did you goooogle it?
Reply:Originally Posted by InsanerideI would think that you knew this has got to be a sucker question. 4.3mA up to 5ma? WTF so low amps? My soldering iron uses at least that much. Also, Tungsten W has the highest melting point of any single element known to man. The ceriated and thoriated doping raise the melting point but thats an alloy and not a element.
Reply:50KV at 50 amps makes me feel better. Remember one thing, were talking about tungsten.What amps do you use and who made your EB guns? AIRCO?  We made our own EB Guns rated for 1.2Mwatts the last time.Last edited by Insaneride; 01-06-2015 at 07:29 PM.Reason: Another sucker
Reply:Originally Posted by sacherjjWhile I know almost nothing about Electron Beam Welding, ... I know of electron beams for industrial processes up in the 40-50mA range, which would be right at the power of TIG. EBW doesn't have tons of electrons, but they are pushed really hard and really deep into the metal I would assume.  Now I really want to see an EBW setup.
Reply:Looking at some sites, I was underestimating voltage for welding.  Looks like there are 60kV and 120kV versions.  So that is 240W to 480W in a tiny focused beam.   Not sure what currents are supposed to be for welding.  I've worked on the electronics side of imaging applications.AHP AlphaTIG 200DX (2nd Gen)Lincoln WeldPak 3200HD Bird Poop GeneratorLotos LTP5000D Plasma Cutter
Reply:Originally Posted by sacherjjLooking at some sites, I was underestimating voltage for welding.  Looks like there are 60kV and 120kV versions.  So that is 240W to 480W in a tiny focused beam.   Not sure what currents are supposed to be for welding.  I've worked on the electronics side of imaging applications.
Reply:Sound like it them.  But I'm OK with it.  I got exposed to another fun thing to read about on the Internet.  So I'll call it a win for me.  AHP AlphaTIG 200DX (2nd Gen)Lincoln WeldPak 3200HD Bird Poop GeneratorLotos LTP5000D Plasma Cutter
Reply:Originally Posted by InsanerideI dont do alot of TIG'n or welding for that matter but about 2 hours ago I used 200Amps with foot pedal so, I dont know what your talking about milli Amps for TIG?As far as EB Guns go, lots of styles out there but basically a a BIG TIG torch.
Reply:Originally Posted by Insaneride50KV at 50 amps makes me feel better.
Reply:From the link HT2-4956 provided; I found these parameters for EB Welding.http://www.ptreb.com/Electron_Beam_W...United_States/Welding is done at lower power than I thought, only 100W to 100KW. Melting and processing are as expected tho from 1KW-2MW.  Voltages range from 10KV to 300KV.Mikegyver, 480v 3 phase, a big transformer and even bigger circuit breaker for power.So in case the op needs a real answer and I was a d!ck; I will offer my two cents. Anwar from IslamaBad,  you say ...we set the beam current to 4.3mA,the welding process goes fine when suddenly there is a change in beam current and as a result in beam also,and the beam current display shows around 5mA,what can be be the possible causes in beam current and the beam?   I say, if the power in IslamaBad experiances a brown out (voltage dropping) the current will try to rise to maintain the set power. Im assuming power in Pakistan has brownouts vs the blackouts we get.I never would have thought about welding tungsten. Whats it for? Light bulbs?
Reply:Anwar,Here's the link to help you get some factory support from PTR.   They offer telephone diagnostics and trouble shooting.   http://www.ptreb.com/EB_Welder_EBW_Service_and_Repair/
Reply:Greeting Ansar! Based off of your location it is likely that you have an Electron Beam Welder from our German sister company, PTR Präzisionstechnik GmbH. From the problem you are describing, and as some others have mentioned, you probably have some preventative maintenance due on your EB Welding System. We recommend that your company have system calibrations completed at least once a year (or more depending on the amount of welding you are doing on the machine). If you follow the link below you will find the contact info for Mr. Mehnert and Mr. Herber- either of these gentlemen will be able to help you with your beam current fluctuation problem.  http://www.ptr-gmbh.de/en/company/af...s-service.htmlWe hope you find this information helpful!
Reply:Impressive attempt at customer support!  30+ yrs Army Infantry & Field Artillery, 25 yrs agoMiller 350LX Tig Runner TA 210, spool gunLincoln 250/250 IdealArcESAB PCM 500i PlasmaKazoo 30"  vert BSKazoo 9x16 horiz BSClausing 12x24 lathe20T Air Press
Reply:Originally Posted by storemanImpressive attempt at customer support!
Reply:Originally Posted by InsanerideFrom the link HT2-4956 provided; I found these parameters for EB Welding.http://www.ptreb.com/Electron_Beam_W...United_States/Welding is done at lower power than I thought, only 100W to 100KW. Melting and processing are as expected tho from 1KW-2MW.  Voltages range from 10KV to 300KV.Mikegyver, 480v 3 phase, a big transformer and even bigger circuit breaker for power.
Reply:Mikegyver, the last EB guns I used (2) where 1.2MW each. The circuit breakers where 2KA. They were big and had a bakelite material lever about 2 feet long to switch on. It was said the levers cost $2,000 a piece. There was a small substation on the other side of the river but I dont know if we used it.  A comparison on an order of magnitude: two cooling towers outside shared a small pond. the towers were about 6 ft wide and about 25 high and 25 wide. The back up generator was only to keep the pumps going during a power failure. A melt down would not be good. The TIG'rs would drop a water line in the troft manifold for cooling a TIG torch.  I rebuilt the best performing EB guns and set a record for the most diffusion pumps re-built in one shift. The diffusion pumps were about 8 ft tall and we ran 6 at a time along with ROOTS Blowers standing about 4 foot tall. I know you know what a roots blower is because you build race car stuf but a 4 foot ROOTS blower blew my mind.Last edited by Insaneride; 01-09-2015 at 10:04 AM.
Reply:Originally Posted by InsanerideMikegyver, the last EB guns I used (2) where 1.2MW each. The circuit breakers where 2KA. They were big and had a bakelite material lever about 2 feet long to switch on. It was said the levers cost $2,000 a piece. There was a small substation on the other side of the river but I dont know if we used it.  A comparison on an order of magnitude: two cooling towers outside shared a small pond. the towers were about 6 ft wide and about 25 high and 25 wide. The back up generator was only to keep the pumps going during a power failure. A melt down would not be good. The TIG'rs would drop a water line in the troft manifold for cooling a TIG torch.  I rebuilt the best performing EB guns and set a record for the most diffusion pumps re-built in one shift. The diffusion pumps were about 8 ft tall and we ran 6 at a time along with ROOTS Blowers standing about 4 foot tall. I know you know what a roots blower is because you build race car stuf but a 4 foot ROOTS blower blew my mind.
Reply:Originally Posted by HT2-4956Let me guess, this was out at Area 51 right?
Reply:Voltage and amperage mean nothing on their own. Watts is power, power is heat. It doesn't matter what the amp/volt combination is that gets you to a given power level.1000amps at 1 volt generates the same amount of heat as 10mA at 100kv, or 1 amp at 1000volts..A given weld requires a certain rate of power to make unless you're changing the time aspect that it's made in. The MW stuff might just be an instantaneous pulse rating (1MW pulse with a duration of 1ms or something, most high power laser stuff is pulsed).Last edited by MikeGyver; 01-10-2015 at 09:54 PM.Welding/Fab Pics: www.UtahWeld.com
Reply:The last EB guns I used ran at about 25,000 volts at 25 amps continuosly (625KW). They were rated at 1.2MW.  The front gun a ran little higher than the back one. It was around 50-60%  and the other around 75% of there rating.  It was a big operation compared to most Hi Vac setups Ive seen. You could fitt a small truck in one of the hoppers.the beam itself was 25amps? what was this thing doing?Welding/Fab Pics: www.UtahWeld.com
Reply:Originally Posted by HT2-4956Yes it is.   I'm a little curious as to how he got aware of this thread.
Reply:Originally Posted by MikeGyverthe beam itself was 25amps? what was this thing doing?
Reply:Hello All,I would like to comment on a few additional topics being discussed in this thread. Electron beam welding uses a stream of electrons (similar to an older style, CRT tube television) as the energy source for welding. EB welding systems use an accelerating voltage that is normally between 60,000 and 150,000 volts and uses a very low current- in the mA range. ie: A 1kW weld could be produced with a 100kV, 10 mA beam.The energy density can be so intense that the metal is vaporized producing the keyhole welding effect. You can see an illustration of this on the first page of this technical paper that shows this effect. An example of an Electron Beam Welding System configuration can be found by clicking the hyperlinked text.Additionally, concerning the comments about tungsten; the tungsten blocks that Anwar references in the original post are typically used for a beam calibration procedure. The beam is focused on the block to check focus and power output of the beam. Tungsten is used because of its high melting point.
Reply:Originally Posted by HT2-4956Yes it is.   I'm a little curious as to how he got aware of this thread.
Reply:Originally Posted by PTR EB WeldingHello All,I would like to comment on a few additional topics being discussed in this thread. Electron beam welding uses a stream of electrons (similar to an older style, CRT tube television) as the energy source for welding. EB welding systems use an accelerating voltage that is normally between 60,000 and 150,000 volts and uses a very low current- in the mA range. ie: A 1kW weld could be produced with a 100kV, 10 mA beam.The energy density can be so intense that the metal is vaporized producing the keyhole welding effect. You can see an illustration of this on the first page of this technical paper that shows this effect. An example of an Electron Beam Welding System configuration can be found by clicking the hyperlinked text.Additionally, concerning the comments about tungsten; the tungsten blocks that Anwar references in the original post are typically used for a beam calibration procedure. The beam is focused on the block to check focus and power output of the beam. Tungsten is used because of its high melting point.
Reply:No we did not directly speak to Anwar as PTR-US would not have been the service provider for his machine, we hope he decided to reach out to one of the support contacts I provided at PTR-GmbH to help resolve the power fluctuation issue he was experiencing. It was not confirmed however that is the typical usage for a "tungsten block". I took some liberties in presuming this as he directly quoted a "block" in the original question; not a 'tungsten application or part' so I figured I would explain that as a caveat to the room for those not familiar with Electron Beam Welding equipment and common maintenance procedures. Maybe you can comment if this was the case or not Anwar...