If you've spent any time working with large assemblies you know how much of an impact assembly cuts can have on your machine performance. Yet as an administrator we've all seen that one person who loves to use assembly cuts to make parts the way they're going to be machined in real life. Make a weldment, then drill a bunch of holes. Put a bunch of parts together then make a hole for a fastener, and so on.
What I've been told is that, basically, for every assembly cut you make, Creo not only keeps a copy of your models in memory, but it keeps a copy of every model with each assembly cut. So let's say you have 2 pieces of metal plate. You have 2 models in memory. Now add an assembly cut through both. So Creo keeps the original 2 uncut plates in memory in case you decide to open either one, and it keeps another copy of each plate with a hole cut in each one for the assembly view you're seeing.
With this theory if you put another hole in the plates, not only do you get the original 2 models, the 2 plates with 1 hole cut in them, but at least another set with the 2 holes cut in them, It's possible for them to have another set with just the second hole in them but I would have to talk to someone in R&D to find that out. There may be more overlap or algorythm to this theory, and limitations to prevent exponential growth, but no matter where you go, what tips you look at, assembly cuts can really hurt large models.
What is the work around? We have to cut things right? One method is to use part level assembly cuts. This option, in an assembly cut, places a feature at the individual part level. This means that assembly hole will always show up in the part level. From a configuration control point of view, how are you going to take a part, cut a hole in it, and still consider it the same as the original part? The part becomes almost custom for that use case, you likely couldn't use it in a different application. This all leads into design intent. If you're using models for engineering design, then it should be for design. There are other parts of the tool for manufacturing planning. Manufacturing shouldn't necessarily dictate how design is performed.
So before using assembly cuts, ask yourself, are they really necessary? Is there another way? Does it match design intent? And please, don't assembly cut all the things unless you really have to.
Feel free to comment below with any of your horror or achievement stories.
-- My words are my own and do not represent any of the companies I work for or with. --