Help with large assemblies and structures

[pclahane]

My organization performs modifications to vehicles, and I would like to know how to better structure our assemblies to decrease load times and increase computer performance. At the moment we have a very bottom up approach to assemblies, where the parts are modeled, then placed in assemblies, which are then placed in installation models. These installation models typically contain a model of local vehicle structure which we will be using to attach our parts and assemblies. Finally all installation models are rolled up into a general arrangement model, which contains a full layout of the vehicle. This approach has worked out well enough for us in the past on smaller projects with only a few installations. However, this approach is not ideal on large projects with many (15+) installations, containing thousands of parts (hardware, designed parts, and reference structure), especially when multiple installations reference the same structure (this means the same structure would appear multiple times in the general arrangement assembly).

What I would like to know is if its possible to take a top down approach; where, the complete vehicle structure is found in the highest level (general arrangement) assembly, and each installation (next lower level assembly) can reference its necessary structure? I know skeleton models can work in a similar manner to what I have described above; however, I do not know if its possible for this reference structure to appear in the installation level drawings. Any help would be appreciated, thanks.

[Chris3]

There is no one thing that will help significantly. You are going to need a combination of things. Unfortunately there aren't a lot of really good specific examples out there.

Reading Material:

Steven LaPha's presentation here is one of the better I have seen: Bringing Large Assemblies Down to Size‌

Tips (in no particular order):

1. Look into interchange assembly substitutions. This is an often overlooked feature that can help a lot.
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2. Do not use assembly level cuts. Assembly level cuts create behind the sceens family tables and can drastically effect performance. If you have to create them make sure to uncheck the automatic update box and manually pick the components you want instead.
3. Use simplified Reps. Creo 4 does a better job of dynamically turning these on and off for you automatically as needed.
4. I know Caterpillar has used collapsed geometry in order to speed up regen times. You might want to look at that. Features can be moved with flexible modeling afterwards if needed.

[BrianTaylor]

What are you doing for Match drilled parts where you assemble a part in place with Cleco's match drill all holes and install say a hi-loc or other permanent fastener.  The better option is to explicitly set what tow hole you intersect with the assembly cut then to say no assembly cuts.

[Chris3]

You can put the hole in the piece parts and then turn it off with a simplified rep at the piece part level. Yes as I stated in my original post if you have to create them then it is best to explicitly state which components are being intersected.

The criticality of assembly level cuts depends on the size of assemblies you are working on.

[BrianTaylor]

I am actively doing the method your describing and it's a nightmare at best.  The reason is all parties must know what is going on if someone screws up any given rep that feed upper level assemblies then you are writing CN's.   Also this dumps you into a use a rep for the drawing to "get rid of the match drilled holes"   This is a pain considering PTC removed the option for View representations for parts it's only exists for assemblies.

[cpoirier]

This is odd, when I follow the link to Bringing Large Assemblies Down to Size I get an error that I do not have privilege to see the page. I am on active maintenance. Does anyone have an idea why I am having this issue?

[StephenW]

The link you posted works for me. The other links in this topic don't work for me and generate the same error you got.

Try the link in your post.

[cpoirier]

Adobe flash issue, I was able to get it working, thanks for the double check.

[dschenken]

The document may be only allowed for those who attended the convention that presentation was made for. It links to

 community.ptc.com/t5/PTC-Live-Global-2015/Bringing-Large-Assemblies-Down-to-Size/ta-p/444618

[BenLoosli]

Search the community for Large Assembly and follow some of those tips.

Here is one that deals with large assemblies: Bringing Large Assemblies Down to Size

Learn how to use and manipulate simplified reps as they help reduce the load when working with the top assemblies.

[MtnDog]

He says in the presentation on page 24 "You can use the out of the box symbolic rep on lower level components or you can have it show sketched lines or datum curves, even those used for things like AFX frames, piping, and cabling as shown here."

Does anyone know how "you can have it show sketched lines" in a symblolics rep?  Simp Reps don't allow features to be shown or not.  Combined States have layer's, but you can't make a next higher level combined state with lower combined states. 

[BrianTaylor]

My single biggest suggestion to you is to utilize envelopes for any and all assemblies.  View, Envelope Manager, Create, pick all the parts, drops you into a creation prompt in my experience surface creation is the fastest and lightest weight.   After you are done creating it, create an Next higer assembly rep  NHA or what ever and then substitute in the envelope into that new rep.   We then create drawing reps and then substitute in those lower level NHA reps....