Appropriate Welding Callout Detail

[zmcvey84]

Hello,

When my company has too many projects for our internal engineering team to do, they will outsource to a local engineering consulting outfit.

This consulting company does have a licensed PE.

I have some concern with the quality of the drawings we receive. They designs appear to be good, but I feel the drawings lack in detail (specifically weld symbols). They feel their drawings provide sufficient detail. When we have prototypes made of their designs, a local weld shop that they are directly connected to will do the work. I believe issues due to lack of detail aren't seen by my company since this weld shop is probably asking questions directly to the consulting outfit.

My feeling is that if I were to submit these drawings to a outside FAB shop, these drawings would not be sufficient.

I've included an example drawing of a weldment. I've only removed our title/revision blocks/bom. Everything else is unchanged. I'd like to hear some opinions on this. My personal feeling is the welding note is not sufficient without also indicating where you expect welds to be placed.

 

[dhengr]

Zmcvey84:
I agree with you, the drawings look o.k., as far as they go, but there is plenty missing on the drawings if you expect any (or an outside) shop to fab this assembly. I would want to see the BOM’s, piece details, more and different sub-assembly drawings, many more dimensions, etc. etc. What is this part? The dimensions in 100ths of an inch are a bit unusual, what fab shop works to 100ths of an inch, what is 3.69? Of course, some mechanical parts and machining would be dimensioned in 1000ths of an inch, or whatever, and they would be toleranced appropriately, but most of this work would be done in smaller sub-assemblies, and then be put into the final major assembly, with fixturing, etc.. I would like to see their structural calcs. on this assembly, their stress analysis, and weld designs, otherwise I think these are just nice CAD drawings. Their weld detailing and sizing is really quick and dirty if the couple notes are all there is on welding. Those are just a couple general welding notes, and not very good ones at that. They are saving some time in weld calcs. at this stage of the game, but if you are making hundreds of these assemblies, they are likely costing you fab time and welding time and consumables. Is this a Mechanical or Structural consulting office? I doubt that the PE has spent much time of this design, but there are plenty of them that don’t know how to do this kind of design and stress analysis, and weld design. What you’ve attached is just CAD and SolidWorks and the like, there is no stress analysis or weld design there.

 

[zmcvey84]

dhengr,

The consulting office does provide additional drawings with the individual component details/dimensions. I'm confident that the FAB shop would be able to recreate each piece separately. When it comes to putting it all together, however, I think it will be a mess. This part would be made in small scale (<10 per year, but high cost). It is a mounting platform that attaches to the front of a backhoe loader, which holds rail gear to travel up and down rail (think railroad). I've seen some FEA analysis from them in the past, and it appears they are at least attempting some due diligence with regard to design intent, FOS, etc.

This came out of a Mechanical office. The welding notes are the only mention of welds in the drawing. I've removed nothing...

Approximately 1.5 years ago I made a fairly large career change moving from a noise/vibration/harness testing background to general machine design. I've been trying to improve the quality of my own work along with my own office's work. Due to my low experience level, I lack some confidence in regards to what is considered a professional level of work. My gut tells me this is not it. I generally try to capture everything you had mentioned in your post (tolerance part, tolerance sub assemblies, identify weld locations with size/type information, etc).

It is becoming somewhat frustrating when dealing with upper management about project timeframes as they like to reference back to this consulting office's rather quick turn around time.

My feeling is that this office isn't providing a finished product, and is merely passing along the work for my own group to have to muddle through down the road.

 

[gtaw]

The word clueless comes to mind.

Best regards - Al

 

[valleytank]

gtaw said it best.

Your issue needs to be addressed by someone with a higher paycheck then you before someone gets burned on it.

 

[BUGGAR]

Look at some of the equipment weld failures in Blodgett's literature. The equipment shown looks just like what you are making. The failures involve lamellar tearing, stress concentrations and fatigue. Of course the failures result from inadequate attention to weld details.

Remember the tradition of the boss standing underneath the first fabrication during its testing? If not, then its time to reintroduce this tradition where you work.