Help understanding penetration

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Trying to learn how to judge correct penetration. Any tips? ( this is with mig welding )This is a weld I did tn to compare my weld to a manufactures weld.  My weld is the closer one. The manufactures is ontop.  Should I see penetration on the bottom of my metel plate? Or should the penetration not go so deep?Don't be to harsh on me it's only my second day trying to weld.
Reply:For your 2nd day welding that looks very good. The weld looks a little cold, try turning the voltage up a little. You also need to keep the puddle a little more on the lower piece of steel.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:yes it was alittle cold, i had intentions of turning the volts up but had forgotten to .. trying to concentrate haha.... thank you
Reply:you're gonna have to turn it up quite a bit to get penetration all the way thru to the back side of that bottom plate!but no, you don't need to penetrate all the way thru that.you're welding with hard wire MIG? That top weld looks like it still has some slag on it, so that's not hard wire, looks like dual shield. your weld looks OK.
Reply:yes hard wire
Reply:There are a couple of ways you can look at how much penetration you are getting.One way is to cut polish and etch your welds. Rick V did a few good posts on etching welds that might help. You can actually see the penetration you are getting.http://weldingweb.com/showpost.php?p...4&postcount=38http://weldingweb.com/showpost.php?p...8&postcount=47The other way is with bend tests. CEP and several others have done several posts on bend testing. The one issue with this is that most "standard" bend tests use 3/8" material, and your little 140 amp class mig won't handle material that thick. Chances are high you will see the weld separate along the sides of the bevel due to lack of fusion with 3/8" material.Some of this is learned also thru experience. You learn to pick up on little things that will tell you a weld is "cold" and lacked fusion. Your tall bead and rolled toes tells me this pretty clearly. Small migs are notorious for making cold welds even if they look "pretty". It takes a skilled eye many times to pick up on poor welds.I can tell you that 1/8" is pretty much the max thickness that little 140 amp machine will do well under real world conditions. If you want better penetration, the simplest way is to get more output power, and that means going to a bigger machine..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Thank u for your help. Yes I didn't even realize I had not turned the volts up . Prior to this weld I was practicing on 16 gauge. Soy volts were set on just about less then half the machine will go.  From now on ill pay attention. Practice makes perfect
Reply:I would say that two words that are sometimes interchangeable are penetration and fusion. In the joint your doing  I would say your looking to achieve 100 % fusion . Part of learning is also to do destructive testing on your own welds. A simple test would be to do a T-joint with the thickness of material you want to use and only weld one side and then bend back over the weld. Give that a try and report your results back here. Remember to keep the weld size equal to the thickness of the material you are using.
Reply:Thanks guy, I bought the welder I did to learn the trade . Also bc I do car work and it would b fine for welding up exhaust work .  I will eventually buy a 220 welder