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Hello,First post on this forum, been a lurker for quite a while.At the moment I'm a hobbyist welder, practicing MIG on scraps of metal mainly.I noticed when I was window shopping for welding equipment, that Lincoln offers a Square Wave model.I've tried to do research online, but all I can find is AC/DC. I understand sine wave is a gradual change between Electrode Positive and Negative, whereas square wave fluctuates between it's maximum and minimum frequency without anything in between.Here's what I don't understand:- What processes use Square Wave?- Why is Square Wave better than Sine Wave?- Are there any disadvantages to Square Wave?I don't see Square Wave advertised much on products (not that I look frequently), is it a gimmick?Thanks for your time!
Reply:Square wave in AC is an effort to minimize the amount of time that the voltage is zero, or near it, between the max positive voltage and the max negative voltage. This reduces the tendency of the arc to extinguish. Square wave machines also commonly offer balance control where you can vary the % of the time that the tungsten electrode is negative (sending heat into work) versus positive (cleaning the workpiece), which allows you to fine-tune the arc with respect to how much cleaning it does (when electrode is positive, electrons go from the workpiece into the electrode, and also clean off some of the aluminum oxides on the surface, which melt at far higher temperature than aluminum, and muck up the weld). AC balance control also helps solve the problem of "arc rectification" when welding aluminum in AC and there's a tendency for the arc to go from AC to DC.
Reply:AC TIG is the only process that uses square wave. On DC there is no wave form. Square wave is useful to break up surface oxidation when welding aluminum and it reduces arc rectification. There is no real downside to square wave...it is the default for most AC TIG welders now, although that being said, many inverters offer other wave forms as well, mostly used for limiting heat input (triangle, soft square, etc.)Miller Multimatic 255
Reply:Square wave - round wave - sawtooth wave is 90% salesmanship and maybe 3% difference in the job in manual welding.Until 1980 we had the ability to produce machines that delivered 60hz from 60hz power in. Electronics reached the point where something simulating a square wave could be delivered to the tip of the tungsten and salesmen went nuts pushing the machines. Square wave sliced, dices and pan fryed and of course required less prep time per unit and less grinding and is you'd just cut a check delivery of your machine would go on the schedule. Oddly, damn few dealers had a square wave demo machine set up on their floor so you could haul your job and the weldor who would be running it over and see if it made a bit of difference. There was good reason they didn't. Red & Blue both sold a lot of units and left it to the LWS to solve the problem of unhappy customers trying to make the machine do what the salesman said it would. Some dealers hopped on the use this blended gas bandwagon and others just threw hands in the air. Electronics got better, and square wave got replaced by sawtooth wave, longer cleaning time on the front slope of the wave, and you know aluminum oxidizes at the speed of light, and sawtooth will solve that so well you can weld an aluminum oil pan still full of oil. Salesmen hit the road, and promised their azzes off, some were so good they'd stand next to the square wave machine the owner had relegated to DC only jobs and tell the prospective buyer "we know square wave didn't solve all the problems, so we invented sawtooth". Blue salesmen forgot to mention the plug on the front of the machine was ONLY for the water pump, and when Fred used it for his grinder it would cost $600 + labor for a replacement transformer, but if you were lucky you could still run the machine and weld with it. Sawtooth didn't sell well. Electronics got better again, and both Red and Blue had a new generation of refrigerator sized machines to peddle and of course slick talking salesmen to peddle them. Direct factory sales agents delivering thru the LWS. There was even an 800 number to call for answers. Blue saw $ and put a little door on the front you could plug PC boards into for the evolving array of wave forms in the pipeline, all developed in the lab and getting kinks ironed out. The cards would only cost about $500 each. NO, disfunctional cards would not be returnable for refund. Red salesmen proudly pointed out Red wasn't going to nickle and dime you to death like Blue. Red had a phone jack on the back of the machine. You only needed to plug the machine in and have it phone home at 110 baud, whatever the hell a baud was. The BIG RED computer back in Cleveland would talk to it's offspring diagnose any hickup the machine had and tell the machine how to fix itself. The computers could even talk at night when Long Distance rates were lower. A lot of Red machines rolled into shops, Blue lost sales, and the LWS had new problems to solve.Which blend gas are you trying to use on that job was generally the first question. Red machines just ran up phone bills. I'm pretty sure both colors sent out manuals of excuses for the LWS to spout. I know dam well a few good shops went belly up between machine payments and scrap they turned out.Electronics got better and Inverter machines rolled out to solve the world's problems. Expensive machines that welded all day on a dime worth of electric, and made you a sammich while they arced. Computer technology was what they had. Blue and Red let the LWS try selling them. LWS smelled the delicate aroma and didn't want to stock the new toys unless they were consigned free of charge. ITW Blue stuck it to the dealers who had built the brand for Miller Electric, and went to factory sale drop ship via UPS.LWS smiled a lot. "Call the guy who sold it to you" became the new line. Can I offer you something in a different gas blend.Old farts who could weld retired.The endless line of Welding Machine Operators Mr Lincoln had predicted in the 60s began arriving at shop doors after they completed training at College where they had 2 full years of excuse making training.
Reply:
Originally Posted by Kelvin
Square wave in AC is an effort to minimize the amount of time that the voltage is zero, or near it, between the max positive voltage and the max negative voltage. This reduces the tendency of the arc to extinguish. Square wave machines also commonly offer balance control where you can vary the % of the time that the tungsten electrode is negative (sending heat into work) versus positive (cleaning the workpiece), which allows you to fine-tune the arc with respect to how much cleaning it does (when electrode is positive, electrons go from the workpiece into the electrode, and also clean off some of the aluminum oxides on the surface, which melt at far higher temperature than aluminum, and muck up the weld). AC balance control also helps solve the problem of "arc rectification" when welding aluminum in AC and there's a tendency for the arc to go from AC to DC.
Reply:https://www.millerwelds.com/resource...eform-controlsthere ya go.Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:https://www.millerwelds.com/resource.../tig-frequencyEd Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Let me try it this way.Until 10 maybe 15 years ago welder manufacturers had 2 product lines to sell; Machines and rods/wire.Business needs to sell to keep the doors open. Only so many welding machines get sold to industry in a given year, and only a small percentage of those are bought by weldors. Most are sold to Purchasing agents who sit in small offices and are having a good day if they can tell left from right. Manufactures employ salesmen to sell boxes full of crap to Purchasing agents who downline it to men who attempt to make it work.Inverters ain't new. They existed in World War 2 to make airplanes lighter so they could get off the ground with more bomb load.The only thing that is new is the transistor/ccd/microchip of the week being engineered in India or Egypt by some guy connected to the Internet. The object of the overall game is to replace skilled weldors with either welding machine operators or robots. Lower labor cost is good, no labor cost is better. Wherever you look in the chain you find a salesman making a commission. At the end of the chain you find more and more work headed back to ReWeld.
Reply:So what are the advantages of a sine wave inverter if a square wave has many advantages?
Reply:Waveforms- from the Miller link I posted.Some inverters also bring control over the waveform itself to meet a specific requirement or operator preference. Some of the waveforms include:Advanced Squarewave, which gives fast transitions for a responsive, dynamic and focused arc for better directional control.Soft Squarewave, which provides a smoother, softer arc with a more fluid puddle than the squarewave.Sine wave, which gives the soft-arc feel of a conventional power source, while using square transitions to eliminate the need for continuous HF.Triangular wave, which combines the effect of peak amperage while reducing overall heat input. Leads to quick puddle formation and, because of lowered heat input, reduced weld distortion, especially on thin material.Achieving maximum productivity often depends on the inverter’s ability to produce a weld bead profile and characteristics that meet the application needs without over-welding, under-welding, excessive post-welding grinding or weld repair. In critical or high-volume applications, only advanced AC controls provide this benefit.Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Air, and inert gasses are non conductive. To conduct electricity, they must be ionized. As sine wave power spends time at low power, ionization can be lost. In part, HI frequency overrunning the welding current helps reduce the problem. When welding aluminum with sine wave, the EN or electrode negative portion of the cycle originates from a small point, the tungsten. Ionization is effective, heat is transferred to the work piece. The return half cycle is needed for cathodic cleaning, originates from a not very conductive oxide coating, it is spread over more surface. It must build to strength before electron flow begins. Cleaning is less effective.Square wave doesn't allow time for ionization to be lost. EP flow (electrons flowing from the work) are effective at lower current. Tungsten can then maintain shape better. Arc remains narrower, more heat is sent to the work. Square wave matters in AC welding of aluminum, and magnesium.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:I prefer using sine wave setting on cast aluminum repairs. The inverter lets me tailor my settings to optimize the balance between a great cleaning arc and lower porosity, all the while maintaining a decent tungsten profile. I like to call it my "Trash" setting
Sine is a much softer arc, therefor, much less disruptive when welding castings. Woks great for blending the edges of the weld to work all the pinholes out, esp. backhand. I do a great deal of marine aluminum repairs and dirty cast is a part of it.A lot of guys did very good work using the conventional transformer machines. When we went to inverters, if you got rid of your old machine, it didn't take long to miss the old arc characteristics for certain repairs. Sine wave made old guys like me happy again. I now have the best of both worlds.If all you do is weld on new shiny stuff, then you would never need sine wave.Miller Dynasty 700
Miller 350P with Aluma-pro push-pull
Miller 280 Dynasty with expansion card
Dynasty 200 DX
MigMax 215 Enuff power and hand tools to create one of anything..... but mass produce nothing!!!
Reply:Square waves also offer a greater amount of power (thermal energy) for a given setting because the wave is always on, where as a sine wave is ramping up and down and spends very little time at full voltage potential. A pure sine wave only delivers 70.7% of the energy as a pure DC or pure square wave of the same volts and amps. THis is calsulated uisng the root mean square formula, or RMS. household power is listed at a RMS value, a 120 volt RMS power outlet actually delivers ~170 volts peak to peak, but when you average it out (ramp up and ramp down along with the peaks) it's an average power delivery level of 120 volt of energy. a 120 volt RMS square wave only needs 120 volts peak to peak to deliver the same number of watts into the weld pool as a 170 volt pure sine wave. When you make settings you are playing with the current side of the formula, but the voltages will be different to deliver a given number of watts.Everlast 350 EXT - Thermal Dynamics Cutmaster 52 - Rogue Fabrication M600 xHD tube benderMilwaukee 4208 Mag Drill - Shopmaster Eldorado Combo mill/lathe machine with DRO.
Reply:Virgil5Loved your summary. Thanks made my day.Last edited by LindeDAL300; 15 Hours Ago at 11:53 AM.
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Originally Posted by LindeDAL300
Virgil5Loved your summary. Thanks made my day. |
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发表于 2021-10-7 15:51:19