jyeffy,
Welcome to the forum.
I'm having a hard time understanding the question. But I'll ramble on a bit and see if I can help by accident.
My feeling "and that is an opinion" is that the direction taken in the text you have in quotation marks would refer to Manual GTAW.
D17 is an aerospace welding code and I believe makes the assumption that anybody attempting to comply will have an intact quality program and expert welders. It's intent is to be minimalist in its application of controls due to the wide variety of materials out there.
An example might be a WPS for Aluminum GTAW... A specific WPS may be created that has required controls on Balence control (dwell time) on each half of the AC cycle, it might also have a call out for frequency of AC cycles in order to produce a minimal fillet size. Furthermore, this fictitious aerospace vendor may be working with asymmetric hybrid power supplies that have amplitude control on each side of the half cycle and work controls for this into specific WPS on projects that merit.
Another simpler componant of the same material might have a simple WPS call out for AC current and electrode type and leave other variables more open to operator descretion.
There are times when controls are practical and times when they are not. I think D17 is valuable because it can accomodate both and satisfy stakeholders as diverse as NASA, Boeing, Rayethon and the Department of Defense.
The Aerospace repair field would be especially constrained by very specific WPS controls... Travel speed, arc voltage, nozzel size, gas flow rates and even the amperage range allowed in a stroke of the foot pedal are going to vary wildly within a single alloy group, thickness and position. A craftsman will need some lattitude in order to get the job done correctly within a procedure.
Also keep in mind... Even though the code is minimalist... Each and every material type and multiple thickness ranges must still be qualified by testing in both procedures and welder performance.
A further example of how the aerospace industry can work within D17 would be dealing with Inconel 718 and cast HIPPED Inconel 718.... While the chemestry of the base metals are so close as to fit in the exact catigory, the HIPPING process makes the Inco much more sensitive to heat input and so many vendors have placed much more strict controls, such as minimal amperage, minimal tungsten diameter, a shield gas with addition of Hy to get a little more pop per amp as well as very strict interpass temperatures... Now none of those strict controls are required for garden variety Inco 718.
To sum it up... My opinion is that Engineering authority and craftspeople are assumed to be high level. If you can create a quality program compliant to D17 they expect you can write a WPS with proper controls... If you are a craftsperson who can meet performance qualification guidelines for D17 it is assumed you know how far to go down on the foot pedal when your welding thin material. Control is available when required.
I appreciate both responses and I am sorry for not clarifying where I was going with the question. What I am getting at is more in line with the commentary regarding the impracticality of the weld settings for manual welds due to the fact that the welder cannot see the meters in order to monitor what is going on at the meters. As you state, a craftsman would be able to recognize whether more or less heat is required to produce an acceptable weld and would respond accordingly. I am referring almost exclusively to aluminum welding but I would think that for manual welding that material would be somewhat irrelevant so long as the base metal, filler metal, cover gas and current type are specified. As you state, preheat, interpass and post heat should also be specified as needed. I would also like to ask why GMAW is always considered semi-automatic when I believe I read that on manual welding one of the controls of the weld could be controlled by a device and still be considered manual. I would think that on a hand held GMAW weld that it would also fit under the definition of manual but all of the SWPS's that I have seen it is listed as semi-automatic. Where I am going with that is to the point of the commentary, when a welder is performing hand held GMAW he must adjust to what he sees at the weld pool and either speed up or slow down or simply stop and make an adjustment to the wire feed speed. Sorry to be so long winded but thanks again for the responses.
jyeffy
your not long winded you are just looking for answers and thats what this forum is about!
"I am referring almost exclusively to aluminum welding but I would think that for manual welding that material would be somewhat irrelevant so long as the base metal, filler metal, cover gas and current type are specified." Yep process and materials specified the rest up to the welder or "operator". But that is not to say that a RANGE of heat input or filler deposit cannot be specified because it can as the need arises. No matter what the process if a specific result needs to be micro managed I think this cert will cover it and allow the part to be engineered as required.
2nd question: "I would also like to ask why GMAW is always considered semi-automatic when I believe I read that on manual welding one of the controls of the weld could be controlled by a device and still be considered manual." I could be wrong here in interpretation but...."one of the controls could be controlled by a device" In GMAW its two variables wire speed and heat....so that would be two variables controlled by device would it not?
THX for coming to the rescue Lawrence!!! And if you have not already done the "trick" I will try to get that video done as our OT is being cut back now so I can breathe!!!
Best Regards
Tommy
Thanks Tommy. I guess I am under the impression that the wire feed and heat input are one in the same since when wire feed is increased or decreased the resulting heat is affected. This would seem to be like adjusting heat with a foot pedal on GTAW only it is set prior to initiating the weld and usually does not get adjusted during the weld cycle. Just looking for clarification. The struggle is taht when specifying GMAW as semi-automatic I would think that all of the pertinant variables listed in B2.1 would have to be addressed. One other question in regards to B2.1, there is a statement regarding variables being recorded as a single value or a range. If a range is used is there some guideline as to the range allowed or is this at engineerings discretion for their processes? Thanks agian for the responses.
your welcome.....I would "think" the range would be set via engineering authority.....however to answer your question well I will have to get some reading done at work...(they own the books). Perhaps an authority here might have a comment?? I am just a welder that likes to read jyeffy.
the range should be provided by the manufacture.
'The requirement of settings for manual welding is not practical.' Welding machines continue to digitize (Miller 350lx, which I use, Aerowave, and the new 700 series) but maybe the comment is simply a recognition that the engineers are still dealing with ...welders.
I am a CWI,and work for a FAA repair station.We qualified our procedures on an actual part that we weld repaired(allowed per D17.1 4.4.4)and our welding procedures are pretty broad in regard to heat input (70 amps max on .030 thickness).We get audited all the time by the FAA and military and have not had any problems.
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