In the service world nothing is static. New parts are frequently added to product BOMs or to service BOMs. If a part is a member of a part chain, the relationship established during creation of a chain can change the next time period when one or more parts in the chain changes status. When one part replaces another at a central location, there may be a period of transition to the new part. During this period, both the old and new parts are ASL parts, and the goal is to "bleed down" the stock of the old part over time, gradually transitioning its demand and resulting forecast to the replacing part. At the end of the transition period, the old part will become a child part, and normally should become a member of a part supercession chain. Setting up a part transition is generally only worthwhile when there is a significant investment in the older parts whose use should be monitored by the planner or when there may be a constrained supply of either the older or newer part during the transition period.

One way to do this transition is to estimate the "life span" of the currently available good stock and any repairable stock that will be repaired and linearly phase out the "old" part and gradually migrate the forecast to the "new" part. Alternatively, you can arbitrarily specify a future phase out date of the "old" part and transfer the demand linearly from now until phase out to the "new" part. Finally, you can accomplish the transition instantly when the cost or stock of the "old" part is insufficient to warrant an extended transition.

Typically, a part that is becoming obsolete or is being replaced will not be removed from a part chain immediately. Part transitions are used to gradually transition a part's demand and resulting forecast to the replacing part.

Part transitioning is only a tool that provides information. It does not actually transition the part in Servigistics. You must replace the part in Servigistics yourself.