HELP! Order of product design development
HELP! Order of product design development
(OP)
My company is looking into what the "best practices" are for doing product design in NX 7.5 based on the current tools available. Historically, we did "top down" design focusing on the finished item and letting that information drive the process part geometry (such as rough castings). Since we initially went to UG/NX, many users reversed this process and began by designing the rough casting, importing and wave linking the component into the finished file, and then "machining" the finished part using sketches/features to achieve the final model of our parts. We have seen some problems with this from our New Product Development group and would like to return to the "top down" process since new tools such as Synchoronous Modeling make it much easier. However, we'd like to follow "best practices" so I'd like to hear how other companies have dealt with this dilemma. Thanks in advance for any and all assistance!





RE: HELP! Order of product design development
If you think about the design process, the finished part is designed first, then the method to manufacture that design is selected based on quantity, lead-time, finish, etc. If the manufacturing process is to start with a casting, now you can add material to the surface that will need to be machined and decide which ones can be left as-cast, just loosen up the tolerance on those.
I have never encountered a design process where the casting was designed and then engineering said "What can we make from this hunk of metal"?
"Wildfires are dangerous, hard to control, and economically catastrophic."
Ben Loosli
RE: HELP! Order of product design development
The contention they have is you must know the geometry of your casting in order to know your finished part geometry, and since it's easier to remove material from the model then it is better to import the rough casting model into the finished cast file and perform all necessary "manufacturing operations" in order to turn the rough model into the finished.
It seems backwards from the design mentality I'm familiar with and more akin to manufacturing engineering processes, but I thought I'd get feedback from other users at other companies to make sure I'm not missing something.
RE: HELP! Order of product design development
"Wildfires are dangerous, hard to control, and economically catastrophic."
Ben Loosli
RE: HELP! Order of product design development
RE: HELP! Order of product design development
Previously I would have rather machined the casting on the CAD model, but now I find it just as easy to add material (with some exceptions) - it just makes more sense to come up with the finshed model (because that is what you ultimately want) and create the casting (add material, remove holes) from there.
RE: HELP! Order of product design development
jerry and looslib are correct. I have a lot of casting tooling experience, and have always started with the finished design, added material, removed holes, and then applied scale.
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RE: HELP! Order of product design development
I thank everyone for their feedback as this has been exactly the type of "ammunition" I need to argue design standardization to upper management based on top-down design processes.
RE: HELP! Order of product design development
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: HELP! Order of product design development
Offset is fine to compensate for material removed while machining, but it's not representative of how an object changes size as it cools.
John R. Baker, P.E.
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Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
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