tig vs. gas

Date 08-05-2003 04:06

because I want to weld aluminum.....light material...mild steel....could someone give me help on gas welding....maybe tips on how to do it better?

By mark8702 (*)

Date 08-05-2003 04:43

any ideas?

By robism

Date 08-05-2003 17:04

by gas , do u mean oxy acetylene?? And if so what do u want to do??

By RonG

Date 08-06-2003 02:09

Mark8702.
My intent is not to talk down to you but! Your question makes it plan you have limited experience with welding and the affect it has on the base material.

We use to get post on this Forum very often that ended with "Remember the best weld is no weld at all". Haven't heard from him for some time now. His point being the heat required to complete the weld causes changes in the base material adjacent to the weld.

You may have heard the term HAZ (Heat Affected Zone). Its a big issue in welding. You can weld with the best process and filler money can buy but chances are you may do more harm than good.

With that in mind GTAW or Tig can make a puddle instantly as with most any electric welding process and filler applied keeping the HAZ to a minimum.

The Oxy / Fuel process is slower to reach the melting point and puts much more unwanted heat in to the work.

There are more technical advantages but I believe this anwers your question.

By dee

Date 08-12-2003 09:45

Ron,
I think youre saying you need to know what you're donig in order to make a good weld with any process, and TIG's advantage is that there's less damage to worry about in the smaller HAZ.
There's a lot to be said, then, on behalf of brazing and soldering as joining techniques, considering the strength of them compared to actual welds, without the heat to damage the base metal at all...

TIG is not exempt from pre and post heat requirements for such metals as require it (as far as my limited experience goes... correct me if I'm wrong) Its apparent the issue you cite is not heat, but heat management... a more complex subject. It's true many heat issues present no practical problem with TIG, but I think I also understand the more abrupt transition between hot and cold with TIG can present different issues. It's not accurate to suggest these problems cannot be managed...

In the end, oxyacetylene IS able to provide very satisfactory welds on a wide variety of materials... it is other, different issues which have caused it to fall from favor as an commercial process.

Mark's concern as I see it is the amount of money he's able to spend, what kind of tools he needs in his shop for that investment, and how much time he's willing to invest learning how to use them properly. The metal's the same however you heat it... you still have to know the same stuff about it. Only the technique and equipment is different. On that account, I continue to hold oxyacetylene as the best place to begin learning, as well as fitting out one's toolbox.

I'd be unable to help answer Mark's question without you to sound my comments from. I do believe there are some advantages to oxyacetylene for some people, otherwise the apparatus would never be sold. I'd suggest they include better initial economy, portability, and over-all versitility.

regards
d

By RonG

Date 08-12-2003 21:21

If I offened I apologize. I wasn't aware we were discussing Brazing. Nor was I aware the question was for advice on purchasing equipment. I just took the question straight on.

To the best of my knowledge preheat and PWHT dose not even approch the upper transformation points of most metals.

We skirt a fine line with the Tempering temp sometimes though.

In my line of work HAZ is a very big issue as is dillution.

What problems did I say could not be managed?

What did I say against Oxy/fuel Brazing? Oxy fuel welding is slower than GTAW and requires much more BTUs than GTAW and sir if you are dealing with a very expensive finished machined items this are not small matters.

I also have a good deal of time with Oxy/Acet High temp Silver Brazing on Turbine blades plus PTAW for the same purpose.

When you say heat management followed by the metals are same no mater how you heat them confuses me. Heat is the engine of change for metals. normalizing, anealing,Harding and tempering are acomplished with heat and oh yes stress relieving.

Again I apologize for nor reading between the lines.

By the way, I recall Aluminum being mentioned. I have done my share of Oxy/Fuel welding of Aluminum as well as GMAW and GTAW. Enough to know I sure don't prefer Oxy/Fuel over the others for any reason.

If you attempt to weld (Oxy/Fuel) on a large section of Aluminum you will learn alot about BTUs.

By dee

Date 08-13-2003 06:05

Ron,
I really took no offense, nor did I intend to make you defensive. Our discussion here is, I hope, going to benefit Mark. Please accept my apology if you read me as contradicting you or criticizing either the accuracy of the facts you cite, or your opinion. What I had in mind was more clear in mind than in print... and perhaps remains so... but genuinely and with all polite courtesies, any real difference of opinion is directed at your interpretation of Mark's question. I interpred "welding" in the context the AWS qualifies for membership. Indeed it is sometimes preferable to "glue" (the word "bonding" is a more expensive verb) metals together rather than "weld" them in the technical sense, so of course I didnt exclude low heat processes from my understanding of the question. As your interpretation may have indeed been the more accurate of our two I cannot justify further energy on a 50-50 gamble, so your apology can only be accepted if you in turn acept mine. I have special affection for niether acetylene nor GTAW... I'm more interested in the integrety of and harmony in our forum.

I'm not positive where I caused confusion, but to extend my remarks in hope of clarity I'll agree woth you and say that metallurgical issues are common to any welding process. (the best splice is no splice &c) You'll be correct to point out that the issues with oxyacetylene differ technically from those with other processes (TIG), but that was mostly my point... there are issues that remain to deal with. It may be unusual in some circles to look at a welding job by first addressing the properties and characteristics of the metal to be welded and then adapting a convenient process to those constraints. My advice to Mark, to help him become a better welder, is that there is a lot to learn beyond what we often refer to as "technique" and it remains important to understand the metal, whatever weld process or processes may be at our disposal; an "exposure" (proficency is more than what's required if you've got basic references you're comfortable with) to chemistry (and physics) is a great help.

Your position in support of the GTAW process needs no defense from me- it's true it makes the cumbersome, if not nearly impossible, sometimes perhaps actually convenient. I'm not being silly, though, pointing out the merit of the tremendous and diverse capability of oxyacetylene. How would one quantify the superior [overall] versitility of it in a comparison to GTAW?

Regards
d

By RonG

Date 08-14-2003 16:35

Were cool.
My biggest problem was that I felt you were coming to the defence of Mark who had posted personal attacks on some folks in another string.

I replied to his question in good faith and then I seen how he was acting towards CT and some others.

I guess he is history now and thats good. We don't need that buiness here.

By dee

Date 08-14-2003 21:40

Wasnt even aware of that problem...
d

By jwright650 (*****)

Date 08-14-2003 21:50

Yeah, I think the two guys that were causing problems are gone now. I haven't seen them surface for a couple of days now, and that aint like them to not cause trouble going on days now.
John Wright

By dee

Date 08-15-2003 02:39

...and I was feeling bad about not having time to log on... left-handed blessings I guess...