How to machine parts with multiple bodies?

[wiengines]

I am starting a new project using CREO 2, and before I get too deep into the project I would like some ideas on how to handle the following situation:

We make small engines (think lawnmowers), and our crankcases are die-cast aluminum with a cast-iron liner that is cast into the aluminum. Because of this, the casting is really a collection of multiple components.

What I am struggling with is how best to create the machined version of this. Do I treat the whole crankcase as an assembly, and add assembly cuts to it? Or do I maybe create machined versions of each component, and then assemble them after the fact?

I've created some simple parts to test out which way makes the most sense, and it appears that assembly cuts have some drawbacks. Namely that every time an assembly that contains assembly cuts is opened; it feels that it needs to regenerate the whole thing. To top it off, windchill then thinks that the file has been modified, so it wants me to check it out...

I am coming to CREO from NX, and NX had a lot more flexibility built into it to that made handling these situations a lot easier!


Using NX7.5 & Creo 2

 

[looslib]

Yes, NX would be the better tool for machining parts.

I have always looked at building my models like they would be built on the shop floor. Your machining should be done on the as-cast engine block. If you use Windchill to release your parts, and don't have modify rights to released parts, you can set Creo to not regenerate read-only parts.



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

Ben Loosli

 

[dgallup]

We have some parts that are brazed together from different materials and then machined so it is similar to your circumstance. To make it even more difficult, we machine many different configuration from the same brazing. We initially thought the brazing should be treated as an assembly and do assembly cuts but found that at some point of complexity it would all collapse like a house of cards and the models that regenerated yesterday and were saved would not regenerate today.

What we ended up doing (and this was all created many years and releases ago but continues to work today), is to merge the parts together in a brazed blank part then perform all the machining to that part. The down side is you lose the differentiation between the different materials. The upside is the models are stable.

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[wiengines]

I also prefer to build my models so that they match what is being done on the shop floor, which is why I decided to try using assembly cuts. But since we are just starting out with CREO, I am not necessarily held to doing things this way - as long as the final model represents the actual part. The two main reasons for this are so that the drawing shows the different parts, and the mass properties are accurate.

We do use windchill, so I will look into configuring creo so that it does not regenerate released parts; but it will be awhile before we get to the point of releasing files.

Using NX7.5 & Creo 2

 

[robertib]

Good luck in trying to stop Windchill regenerating released parts - we have only been complaining about it since M010. The workaround that we have been told is the official way to do it is to select the parts in the workspace & lock them (under File menu).