| # Offsetting from finish date to start date The second part of offsetting, offsetting from the finish date to the start date, depends on the order type. This part of offsetting differs for production orders, purchase orders, and distribution orders. The offsetting of the various order types is described in this section. Production orders Three factors determine how a production order is planned/offset: Routing planning: If the estimated start date of the production order is before the date in the Start of Fixed Lead-Time Horizon (SFC) field in the Items - Planning (cprpd1100m000) session, you deal with short term planning. Consequently, production orders are planned in a detailed way. The production order is planned with routing, routing operations and quantity. The order lead-time is the sum of the operation lead-times. Fixed order lead-time: If the estimated start date of the production order is after the date in the Start of Fixed Lead-Time Horizon (SFC) field in the Items - Planning (cprpd1100m000) session, you deal with long-term planning. Consequently, production orders are planned in a less detailed way (to gain performance). Therefore, if the estimated start date falls after the date in the Start of Fixed Lead-time Horizon (SFC) field, then details are skipped. Instead, the fixed order lead-time is used to plan, without using routing and operations. Note The estimated start date is determined by planning backward the fixed Order Lead Time that is defined in the Items - Production (tiipd0101m000) session. Generic items: Sometimes, the production order involves a generic item. The generic routing has a set of possible operations. The choice of operations depends on the configuration, so in a planned order for a generic, not yet configured, demand all operations are planned. This offsetting differs from normal items. The following sections in this chapter discuss the following three situations: Routing planning Planning with a fixed order lead time Planning of generic items Routing planning A production order consists of a series of operations. The sequence of operations is managed by the routing. One item can have multiple routs, with various sets of operations, dependent on order quantity. In addition, you can model phantom items, which result in a network of parallel operations. The impact of phantom items on planning is described later in this chapter. One planned operation contains the following lead-time components: Queue (Next Operation) Average Setup Production run time, based on cycle time Wait Move Production time can be either quantity dependent or fixed, which is determined by the Fixed Duration checkbox. Two options are available: Normal, no fixed duration ( Fixed Duration checkbox is cleared)
    Production time = cycle time * order quantity / routing quantity
Fixed duration ( Fixed Duration checkbox is selected)
    Production time = cycle time
If you use the detailed routing information, the offsetting of two operations looks as follows: Production orders, offset operations Operation overlap The previous figure shows how you can plan two operations sequentially. Operation 20 starts when operation 10 is finished. If you use a transfer batch quantity or percentage, operation 20 can start when operation 10 is partly finished. Production orders, operation overlap Network of phantom operations If item A has phantom items B and C as components, the production order contains the operations of item A, as well as of items B and C. If, for example, phantom B is required on the third operation of item A, and C is required on the second operation, the planning looks as follows: Production orders, network of operations Capacity The required capacity for a production order is derived from the operation lead times. Occupation factors indicate how many men or machines are involved in the operation. Only the setup time and the production time require capacity. For the two types of production times, the capacity calculations are: Normal, no fixed duration:
    Man hours = average set up * man occupation for set up + cycle time * order quantity  * man occupation for production / routing quantity
    Machine hours = average set up * machine occupation + cycle time * order quantity  * machine occupation / routing quantity
Fixed duration:
    Man hours = average set up * man occupation for set up + cycle time  * man occupation for production / routing quantity
    Machine hours = average set up * machine occupation + cycle time * machine occupation / routing quantity
In the Enterprise Planning resource plans, either man or machine capacity is stored based on the Critical Capacity for Planning field in the Work Centers (tirou0101m000) session. Related topics Calendars in Enterprise Planning Horizons and time fences Time Zones in Enterprise Planning |