Time for TIG welding

[lownox]

I am hoping someone more skilled than me can help me out. We are manufacturing steam manifold assemblies. The gray area that I am dealing with is TIME.

Each of these manifolds is completely unique and custom designed per job. Calculating the time for the shop routings (labor hours) seems to have been completely arbitrary. With the cost of materials rising fast, it has become even more important to cost these items as accurately as possible. This way the sales guys can price them and realize the profits.

So, here is my problem. I have basically challenged the guys who have been setting the TIME... saying "Hey guys, these routings look high, can we take a look?" The response has been "we are using 2 minutes per inch for TIG welding"

Now I know this is not the case, but in any rate, I have this question... Is this kind of blanket rule an appropriate way to do this? Surely there is more to studying the time it takes to weld these manifolds than this.

Any opinions are appreciated. Thanks.

 

[MintJulep]

Two minutes per inch seems like a perfectly nice number.

I'm sure that lots of study went towards its determination. Some bright folks probably spent a lot of time watching a lot of welders welding a lot of different things, added it all up and came up with two minutes per inch as a very nice average number.

They may have even watched some steam manifolds.

And they probably watched some thin sheet, and some thicker plate. Some aluminum, some steel, some stainless....

Did they watch and time joint prep, cleaning, measuring, marking, fixturing...?

Basically, do your estimators know what is in that two minutes per inch, or did they just look it up in a book somewhere, sometime?

 

[metengr]

lownox;

The response has been "we are using 2 minutes per inch for TIG welding"

Now I know this is not the case, but in any rate, I have this question... Is this kind of blanket rule an appropriate way to do this? Surely there is more to studying the time it takes to weld these manifolds than this.

No. There is no blanket rule for this because you have various parameters in part fabrication - joint geometry, thickness, and welder skill level with the process. It could be that someone in the past had established weld time and this value has stuck or the shop welders are blowing fumes up your ......

The only way to understand what is going on is to have several shop welders weld manifolds with GTAW (TIG) and compare welding time between them. Another approach is to compare part manufacture using GTAW (current) versus SMAW (stick) process. Now you can compare apples to apples, and decide which welding process is perhaps more efficient in time and costs (consumables of GTAW versus SMAW).

 

[griffengm]

Lownox,
MJ has a point. JUst what is considered in the two minutes per inch standard?
My experience says that when a blanket standard is applied one product gives the customer a bargain and the other rips him good. This translates to your company is making good money on some jobs and losing their butt on others. How do you know how many of which are increasing/decreasing your bottom line?
Some companies hire an industrial/manufacturing engineer with the idea that the engineer is to develop standards on the existing processes and then move on to other projects. Eventually processes and products evolve but the standards stay the same. The company upgrades equipment to improve production, hammers on labor to reduce costs when the real culprit is out-dated, mis-applied process information.
Thanks for the chance to rant!
Break down the operations to the most sensible components and make them the routing steps. The welding figure may be very usable if you find that fit-up is the most variable step or that post-weld work is the most influential. My guess is that you will find some combination of factors outside of the actual welding determines the time. Now the challenge becomes applying the appropriate factors. Hire experience!
Griffy

 

[Capntom]

Frequently "torch time" is the shortest category in some welding. As stated what is included in that "two minutes" is the important number. What code? What service class or inspection criteria are required, how many passes, preheat, joint prep, paperwork to be filled out, material certs..... Do an internal test. You will not like the results. I have done this before. Find out what was quoted before you won a job, hand the welder the piece, ask him to come see you when it is all done. Don't tell him what you are doing, ouch............

 

[berkshire]

Capntom
So do you punch the stopwatch when he leaves your office and walks 1/4 mile back to his welding bench, or when he sits down and lights the torch?
B.E.

 

[Mr168]

That would depend on how far you break down a time study. Some time studies break down into essential movements, i.e repositioning a piece, reaching for a part, picking up the torch, etc. These are typical for very high production work.

If they consider "time for TIG welding" to be actual arc time, then you sit with a stopwatch and take the time only that the arc is lit. If that "time for TIG welding" encompasses the time it takes to weld the entire piece up including repositioning, etc, then you pretty much go from the time he gets to his bench to the time the piece has had all welding completed, and possibly until its cool enough to handle.