Bob asked me the following at the end of another post.
Out of curiosity in regard to weldment drawings, do you model your welds?
We sometimes work with thick plate and the welds become important from both a weight and clearance standpoint. So, for example, if we have a large fillet weld adjacent to a row of bolt holes, we need to make sure we have sufficient clearance between the weld and holes so our washers and nuts miss the welds. I have found when we fail to model things like this we tend to get bit during assembly.
Since we model the welds I like to have a configuration with welds shown and welds hidden. I use the welds hidden configuration for orthographic views where we call out weld via symbols and the welds shown config for iso views, assemlbies, and total weights. Modeled welds shown in ortho. views tend to create too many lines and make the drawing hard to understand.
Just curious how others handle this.
We do not model the weld beads in our production models, but add them as needed to reference copies used for FEA or Weld Robot programming. The weld beads are strictly defined on the 2D drawing.
We chose not to take the time to model the welds, mostly because of the potential confusion that would be caused by having a weld modeled that didn't exactly match the callout on the drawing. One side benefit to this process is that we can rev a drawing to change a weld, and not have to update the weldment model, and then all the assemblies that use that model.
As you said, showing the welds in Ortho views is messy, and our drafters didn't like that at all. Espcecially if the weld bead is modeled with some interferance. Our Tooling group and some others would like to have the welds in the model. However, they would require that the welds display be exactly right (kept in sync with the drawing,) or not shown at all. If modelling complex weld beads gets easier, and keeping the drawing in sync with the model is reliable, we will revisit this. It would be benificial for us to have a calculated weight that included weld material.
In addition to welding plates and tubes together, we apply a lot of hard facing material to our down hole tools. You can Google "hdd back reamers" and look at images to see some examples of the hard facing we apply to parts.
A place I worked for did a lot of weldment models but did not model welds. Having all those weld parts to manage and maintain was considered less than worthwhile. We estimated total weld weight and inserted an empty part with a user defined mass equal to the estimated weight so it tracked with downstream models and drawings.
How to estimate the weight is an issue. If the weldment is fairly simple you can multiply sections by lengths come up with volumes. Otherwise we used a percentage like 3% or 5% of assembly weight without welds depending again on educated guesses. The weights were for shipping and hoisting estimates so a positive margin of error was advised.
I don't model or even call out welds at all. Starting a CAD department from scratch for a sheet metal fab shop, this is something on the radar, but will likely be a year or two off. After the first year, I'm still struggling to keep up with production and make gains on how the file are named, organized, and managed to get the sheet metal cut and folded.
I would think weld beads would be used in structural steel weldments moreso than sheet metal.
True, but,......as some of my sheet metal assemblies contain folded 10mm plates also, they'd count as both [structural & sheet metal], right??
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Sure. "Moreso", not absolutely. It's up to user's discretion and needs. I'm just thinking that weld beads aren't likely to exceed sheet metal thickness so tend to be, to generalize, a small percentage of total wieight, etc. Now if you consider sheet metal to be about 5mm or 3/16" thick then it's a different animal.
Now when you're welding 30mm plate with 25mm bevels filled with compound bevel welds then you got some mass there.
We tend not to model welds unless they are absolutely needed for clarity in a detail view or to illustrate a manufacturing work flow. Examples might be where there is post-weld machining or in some section views that show weld preps and the welds themselves.
Sometimes welds are modelled for the purpose of FEA but then the models will be analysis models rather than manufacturing models.
Lots of customers place weld beads on welded assy in my country. It is important, bacuse its mass will be added to all.
The main challange is coming when they want to show them on drawing views. Our standard supports "caterpillar" weld beads, but SE doesn't!
The second challange when they want to collect these weld beads infos in a table like "parts list"...
Now, they do this manually.
If you are going to put welds into a table, I would use the needs of the ASME system to organized how things are presented. IE allow a detail to be referenced for each weld for quality control and weld procedure control.
I currently do not have a need for this, but I have done ASME pressure vessels for three different companies where this would all be a huge deal when the authorized inspector (AI) has to sign off on all the welds. There also needs to be a tracking system between x-Ray's and the weld numbers.
Like with any BOM or list for a drawing, it comes down to listing shape, sizes and materials in an organized fashion.
Engineering can be most simply put as specifying a volume and material for some purpose.
Engineering is packaged into drawings.