Animate Fade in Inventor Studio Environment.'
Go from 0% visable to 100% visable. You can set when and how fast this occurs for each part.
If you can't figure it out - attach your assembly here or a small representative assembly.
maybe you mean rolling down the End of Part marker in the feature tree - feature by feature.
More information is needed.
Sorry if I was not clear, is that I want to simulate a piece being welded in the other, and would like to appear gradually loose, as if welding even understand?
Many members here do not speak English as their first language.
Maybe if you post in your native language someone here that speaks the same language can answer your question.
Post your assembly and maybe the question will become more clear.
Do you mean something like an assembly instruction for your shop, where first it might only show 2 parts being welded, then another view adds some more, then another view adds more to that, and so on, like the attached file?