On 02/14/2012 12:01 AM, gene heskett wrote: > On Tuesday, February 14, 2012 12:53:29 AM Mark Cason did opine: > >> On 02/13/2012 10:03 PM, gene heskett wrote: >>> On Monday, February 13, 2012 10:21:08 PM Jon Elson did opine: >>>> gene heskett wrote: >>>>> Guy's, maybe I don't understand cutting alu as well as I thought. >>>>> >>>>> All along, I have believed that it was more important to keep the >>>>> oxygen in the air away from the cutting surface in order to slow the >>>>> formation of alu oxide on the surface, which in normal air, not >>>>> blown, can get a good start in 0.001 seconds >>>> I have some doubts about this. The oxide will form unless you run >>>> under Argon shielding, >>>> which may not be real practical. >>> Nitrogen should work equally well since the idea is to flood away the >>> oxygen. And its 99% cheaper. >> Not exactly, Nitrogen can react with the magnesium in various >> alloys, There's a reason why noble gases, specifically Argon, and >> Helium are used as shielding gases. The only exception is CO2, where >> it's used in welding. > There, particularly in a mig setup, its main reason is to add its carbon to > the puddle, hardening the weld. Same effect as firing up your Smith Wrench > and running a long central feather in the flame by reducing the oxygen flow > a wee bit. You can make very very good welding rod out of a pile of coat > hangers that way. ;-) But you don't have the control over the carbon > added that way in comparison to the Smith Wrench, that is almost unlimited. > > Cheers, Gene
Off topic, butCO2 isn't technically a shielding gas, it is a reactive gas. Along with increasing carbon content in a weld, CO2 also adds heat to a weld, resulting in deeper penetration, at the expense of a bit more slag, and lots of spatter. Using pure CO2 is an old trick to make a small welder weld like a bigger one. Very thin sheet metal can use pure Argon, up to 95/5 AR/CO2 mix, but basically, the thicker the metal, the more CO2 you want. I use pure C02 from 1/4" on up. I have both CO2, and Argon tanks, with their own flowmeters, and a custom made mixer, so I can dial in the exact mixture, from pure argon, to pure C02. Getting the percentages set right is a bit touchy, but it works, and it's a lot cheaper than proportional gas mixer. Sorry, I can go on for hours on the various methods of welding. It's one of the first things I learned when I was very young, and I'm quite good at it. I have 5 different welding machines, and my favorite is my 220v Millermatic, but right now, my most used machine is my little Lincoln 140, running FCAW, because I can take it pretty much anywhere there's a 120v plug. I have a nice Lincoln Precision TIG, but I don't use it enough to keep my skill level up. However, welding up Dad's transfer case a couple weeks ago, really tested the machines ability, as well as my skill. It hasn't self destructed yet, so I think I did ok. As for the coat hangars, I haven't used any since I was a kid, "borrowing" Dad's torch to fix my bike. Dad would notice when a filler rods came up missing, but Mom never really noticed a coat hanger missing. Smith Wrench, never heard that one before. I'll have to remember that :) -- -Mark Ne M'oubliez ---Family Motto Hope for the best, plan for the worst ---Personal Motto ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
