Hello js55, I might add a few comments. In a different thread, this topic was brought out during the course of the discussion. For a given wire diameter there is a cross-sectional density which enables it to provide a certain current carrying capacity, once that current capacity has been exceeded I do believe that it no longer provides a stable conductor. That statement is not based on any scientific proof, but merely how I view what is going on. In particular, I believe this to be true of the flux-cored electrodes and to a lesser degree the solid wires. My experiences with running many different diameters and types of wires has brought me to experience the porosity issues with some of these wires, argueably you could say that there are also lots of other variables that can influence these conditions(moisture in the fluxes of cored wires due to exposure and incorrect storage, external contaminants such as oils that are on the wires). When considering flux-cored wires, both gas-shielded and non-shielded, stick-out can have a great influence on how the fluxes are activated, not enough stick-out and the fluxes don't perform as designed and porosity can result, to a lesser degree, maybe it is possible that the over-amping of a flux-cored wire may cause a deterioration of these fluxing agents as well(similar to what occurs when a 5P stick electrode is operated above it's amperage range), rendering them ineffective and causing porosity. As I said before I don't have any scientific proof to back up this theory, but I have seen the results in many instances. A few more items for thought. Regards, aevald
Allen,
I think there is substantial research to backup what you are saying. And I agree.
Alan,
I like what you said about the FCAW wire and how improper stickout can have negative affects on how the flux disassociates to produce shield gas... I do think improper FCAW voltage settings (too high) might cause porosity.
Too high voltage for GMAW and solid wire is more likely to cause globular transfer when short circuiting transfer is the preferred mode. With the spray transfer mode, too high voltage will cause a long arc, undercut and burnback conditions typically... Porosity would be much less likely.
Hello Lawrence, I too would agree with your assessment of high voltage regarding the GMAW process, mainly I have noticed the issues you discussed and not porosity. I have also noticed substantially increased tip wear and failure, I believe this may be due to the wire possibly making the transition from the solid state to a somewhat plastic state while still passing through the contact tip. This can also cause erratic feeding and what I call the shotgun effect(even though it might be in the spray mode of transfer, I have experienced intermittent spray). Here again no scientific basis simply a possible observation and reasoning thing. Best regards, Allan
Allan,
Ed Craig talks a bit about that whole wire catching in the tip phenomina... He attributes some of it to inconsistant boring of contact tubes by low cost vendors and also inconsistant wire diameters caused by poor quality standards by the manufacturers who draw the wire. I also think your right about high voltage effects causing minute differences in the wire that could be trouble over time.
I never gave much thought to who's contact tubes I bought....... but I read Ed's article and it made me think about my tour to the Miller Electric plant where they actually produce alot of there own copper and brass consumables (including contact tubes). I think I'll give the higher cost American made consumables a try and see if I can tell any difference... We don't run long hours or consistantly high feed rates so I don't know if our school will be a good barometer of quality.
Hello again Lawrence, over the course of years I have had experience with running a number of different manufacturer's consumables, guns, etc. At our school we currently use Bernard guns and front end parts. I have used the OEM Bernard parts and I have also ordered in the after-market consumables, I believe you are correct when you say that your setting may not give you an accurate read as to consumable life, mainly due to the abuse that students and newbies will put upon these items. I believe that failures in industry are due more to hard service and maximizing use than necessarily the type of abuses that students will cause to consumables. Having said that, I also have had experience with various other manufacturer's products when I have gone to work out in industry. Regardless of the manufacturer, I do believe that the OEMs generally work better with their specific products. Probably due to the reasons that Ed Craig points out regarding consistencies in manufacture and proper sizing. I realize this thread has gotten off topic somewhat, but I also believe the information here can be of benefit to many. Best regards, Allan
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