-> You can move an entire production cell within your
-> facility, but as long as the process flow within that
-> cell is not affected, there is no need for customer
-> notification.
This is true if there is no 'location sensitive' equipment / station(s) within the cell. Whether or not a partial re-PPAP is required is not simply an issue of process sequence. When there is 'location sensitive' equipment / station(s) in the cell a partial re-PPAP is typically required.
That is why I used the press example above as an 'extreme' example. Large presses can stamp differently when location is changed. The characteristics of the foundation it is placed on are important. There are a number of considerations, not the least of which is vibration characteristics, which in part will change when the base on which the press rests is changed. A change in the vibration characteristics of the press can change the way the tools mate (one effect). While the press made acceptable parts in its old location, it is not a definite fact that if you move it it still will.
Bear in mind that typically you are not looking at a complete re-PPAP of the entire process (the sum of all sub-processes), but rather a partial re-PPAP - re-PPAP of the affected sub-process.
Also remember what is really going to happen. If you move a machine or a whole cell (all sub-processes which make up that cell) you're going through the motions anyway. You're going to have to get everything set up and do run-offs. Surely one would not move a cell and simply say "GO!" unless the sub-processes are simple and neither equipment nor process requirements are 'location sensitive'. The question is more of what the SQA will want sent in as evidence.
One more 'extreme' case. You decide to change location of storage of certain finished materials. The materials are metal. When PPAPed, the storage location is inside the 'heart' of the facility. You decide to move the storage to the shipping dock area which is open to the outside air most of the year. Your plant is in Ohio and you make the change in January. In July, which is humid and hot, the customer starts receiving rusted product. This never happened before. The question of 'what changed' is hidden, at least temporarily, as the association with the January change would probably not be the first hypothesis of the problem root cause - "...heck we did that way back in January...".
The Bottom Line: When something is moved, one wants to take a long, hard look at possible / potential effects of that move. Even if it's just a storage area.