What is an example of a product "becoming a trivial and nonessential component of another product"?

Suppose the U.S. patent claimed a process for refining aluminum.  It would probably not be infringement to import an automobile having an aluminum ashtray, even if the material from which the ashtray was made could be traced back to the patented process. At some point, the imported product becomes too far removed from the claimed process to regard the importation of that product as infringement.