Machining after assembly. WAVE/Promotion 2

[PrintScaffold]

Hello John! This is a spin-off topic from NX10 thread.

Machining after assembly is a very frequent scenario in real life manufacturing. Typically assemblies are machined after welding, but not exclusively. Currently NX allows to model this situation through use of body promotion (either direct promotion or Assembly Cut feature) or WAVE linking of body. I have no problem with either scenarios, although all of them have some downsides here and there. The bigger problem is with users, especially less qualified ones, who often find it difficult to quckly grasp the technique. Therefore I'm quite interested - is existing approach going to be changed in the future? Are there plans to implement the solution which would allow modeling operations on the component-level bodies directly from the assembly level, without need to link or promote them beforehand? Is this possible at all with current architecture and geometric kernel of NX?

Industry creates wealth!

 

[JohnRBaker]

I think it's safe to say that if any new capabilities are implemented to make this process more straight forward or easy to use, it will still, under the covers, use something like Promotions (probably not WAVE). This is how we handle things like the Assembly Cut function, it's actually using Promotions behind the scene. The same with Deformable Parts, it using a Promotion type body.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
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[PrintScaffold]

Sorry for the late reply! Thank you!

And while we are at it, I have a question regarding issue of double weight of assembly if WAVE links are used.

Eventually I came up with the following solution (provided that Advanced Assemblies license is present): components, bodies from which are WAVE-linked to the level of the assembly, are set as non-geometric. Then component group is defined which includes all components except those which contain UG GEOMETRY = NO attribute. This component group is then set in the Advanced weight management window, negating the extra weight and resluting in correct calculation of the cached weight. Would you call this a good practice? Maybe some better way is present?

The only issue I found with advanced weight management is that it is effective only for single level of the assembly. In other words, if ASSY1 is set up to exclude certain components from weight calculation through componet groups, it will work only for the ASSY1. If I create ASSY2 and include ASSY1 into it as a sub-assembly, the components invisible by ASSY1's weight calculation will again be visible by ASSY2's. Therefore, I need to set up same component groups at every assembly level, which works good but requires extra attention. Is this as designed?

Industry creates wealth!

 

[JohnRBaker]

If you're WAVE linking into an Assembly the parent object is also a Component then you'll have to manage the weight as best you can and the approach your using is as good as any. Of course, if you ARE WAVE linking into the same Assembly as the parent Component and there is NO overiding reason for having BOTH the Component and the WAVE linked body as two separate objects in the same file, then I would use Promotions instead and you'll not have to worry about the weight issue.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[PrintScaffold]

Overriding reason - and quite a curious one at that - can be that certain companies prohibit promotions and disable them in their NX installations.

Other reason can be that promotions are a bit less than perfect if you need to replace a component which is the parent for promotion. Especially if machining occurs on multiple levels in the cascading assemblies - and I came across cases like this. If you need to replace a component, WAVE is great because link stands and you only have to re-parent it. But on the whole, promotions are good. Especially if users understand them well and use accordingly.

Industry creates wealth!

 

[carlharr]

When WAVE linking components into a parent assembly for machining operations (or other reasons e.g. mirror part), you can suppress the WAVE linked components when you're finished.

This takes care of the weight, and also prevents loading unnecessary data. If using Teamcenter and Vis, it also ensures that only the final part is shown in a load of the JT assembly.

http://www.jcb.com

NX 8.5 with TC 8.3

 

[cmacca]

I wish promotions could be re-linked rather than converted to WAVE or having to redo the promotion. Are there any plans for this in the future?

NX 8.0.3.4 mp2, TC 8.3

 

[PrintScaffold]

When WAVE linking components into a parent assembly for machining operations (or other reasons e.g. mirror part), you can suppress the WAVE linked components when you're finished.

Exactly what I wished to avoid when I looked for methods. Suppressing component takes it away from product structure and suppresses update of WAVE link. AS far as I'm concerned, this is a disaster waiting to happen.

Industry creates wealth!

 

[JohnRBaker]

Overriding reason - and quite a curious one at that - can be that certain companies prohibit promotions and disable them in their NX installations.

Dare I say, you work for a stupid company. It would be like buying a complete set of Craftsmen handtools and then throwing away all of the open-end wrenches because there were also box-end wrenches of the same size. While they both loosen and tighten bolts, they are designed for being used in different circumstances.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[Dave K]

John, I bet the disabling of Promotions, goes back to when Wave first came out, and many of us thought Promotions would go away. UGS (or whatever they were called then) created an environment, where many of us thought that, especially with that "convert promotions to wave" option.

-Dave

NX 9, Teamcenter 10

 

[JohnRBaker]

Yes, I'm sorry to say that many people came to that same wrong conclusion. If it was the result of poor or vague positioning, by our people, of these two similar yet different functions, we apologize as that was not our intention. In fact, since that time we have added several enhancements to UG/NX, such as Assembly Cut, Deformable Components, which uses the 'Promotion' function internal to the feature being created. If we had used the WAVE function these features would have never been able to be done in a manner which would have been acceptable, since to do so would have resulted in exactly the same issues with double bodies and double mass as has been mentioned here in this thread. What you need to do is to learn differences between these two functions and then use them appropriately with the understanding that despite their apparent similarities, they were designed to do two different things and that choosing to limit your use to only one of them will lead to less than optimal results.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[Dave K]

Since I'm dealing with a lot of new users, I've written up a how-to/best practices document on the differences, and uses of each. Is there anything from Siemens like this? I've looked thru the PLM World presentations, and didn't find any.

Also, is there any ER in process, to make re associating Promotions possible? If not, I will spawn one.

-Dave

NX 9, Teamcenter 10

 

[JohnRBaker]

I'm not aware of anything official that has been produced. Note that there might have been something written when WAVE linking was first introduced to help explain the differences between WAVE and the exisiting Promotion functionality, but that was many years ago (1997 to be exact, when WAVE linking was first introduced with the release of UG V13.0).

As for adding more 'WAVE-like' behaviors to Promotions, to some extent this may be counterproductive and could potentially lead to even MORE confusion about which approach to use when.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[cowski]

In fact, since that time we have added several enhancements to UG/NX, such as Assembly Cut, Deformable Components, which uses the 'Promotion' function internal to the feature being created.

Just out of curiosity, if a site has the "promoted" option disabled, will it also disable these new functions that use it internally? Or does the 'disable promotions' option only apply to explicitly created promoted bodies, allowing the system to use them internally as needed?

www.nxjournaling.com

 

[JohnRBaker]

NO, the 'Disable Promotions' option ONLY affects access to the explicit Promotion function, not the other functions which may be utilizing the technology behind the scenes.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[PrintScaffold]

Dare I say, you work for a stupid company.

Fortunately, I do not work for such company. But I know that some companies prohibit promotions, and sometimes I come across them.

Anyway, 'WAVE vs. Promotion' is always a hot topic - and this thread proves this once again. Obviously, promotion better models the real-life situation and does not create problems with assembly drawings and weight calcualtion. If it supported re-parenting better, it would be the ideal tool for machining after assembly.

John, could you tell us a little more history? When did Promotion first appear? When was it re-done from scratch? When did appear the tools which use promotions as the engine, like Assembly Cut and Deformation? These are actually useful things to know because they can serve as a powerful argument when Promotion has to be... well, promoted.

Industry creates wealth!

 

[JohnRBaker]

I don't have an exact date, but it must have been around 1995, perhaps early 1996. It was redone after WAVE was introduced since it did share some of the same behind-the-scenes archtecture and so it was sort of modernized, at least from a architectural point of view, around 1999-2000, but this had no real impact on how you used the Promotion functionality but it probably did improve the performance and reliability.

As for where NX is leveraging the Promotion tools, Assembly Cut was introduced in NX 3.0 (around 2004). Sorry but I don't have a definitive date for Deformable Parts, but they've been around since at least NX 1.0 or NX 2.0.

Anyway, I hope this helps.



John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[Dave K]

John, mind if I email you my Wave and Promotions document, to get a Siemens opinion on it?

-Dave

NX 9, Teamcenter 10

 

[looslib]

Deformable parts was intoduced with NX1, since that was the last version I played with in beta testing.


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli

 

[Dave K]

On the GTAC download site, there is a "NX_WAVE_Control_Structure_Tutorial.ZIP" which was dated 8/13/2002. So, something around then inspired that.

-Dave

NX 9, Teamcenter 10