When using both SNP and PPDS to plan the same production lines in an APO environment, one of the most critical design decisions you can make is how the SNP and PPDS horizons interact with each other.
Like many settings in APO, there is no real “right” answer to this question. It all depends on the scenario at hand. In fact, the setting used can vary within a company, between divisions or even between lines in the same plant. In the next few entries we will explore the differences of each horizon and how we can use them in an overall design.
SNP Horizon Defined
Horizon in the product master defines the bucket in which the SNP heuristic begins to create a solution. This time, horizon consists of the week defined in the product master until the end of the planning horizon is solved in discrete time buckets. Stock transport requests are created as an unconstrained demand signal to the production location. They are requirements without any consideration of production or transportation capacity. These relationships are driven by transportation lanes or inbound quotas or a combination of both. The requirements are offset by the transportation lane lead time as defined in the transportation lanes.
Planned orders are generated with SNP PPMs or PDSs for production master data, and the level of detail is meant for rough cut capacity planning, not detailed scheduling. Generally the SNP planning books are used to manage the SNP plan, balancing demand requirements with available capacity. The decisions made in this horizon are not concerned about run sequence but balancing capacity required to meet the demand signals available. Capacity leveling heuristics can smooth capacity in this horizon, but can not generate or delete orders, only smooth orders created by the SNP production planning heuristic.
Extended SNP Planning Horizon
Same as the SNP horizon, no orders will be generated prior to the horizon start date, however SNP orders can be manually entered prior to this horizon.
SNP Planning Horizon Characteristics:
- Single product focused in the planning book
- Used to manage long to medium term production plans
- No scheduling activities or sequencing possible
- Planning and capacity managed in discrete buckets
- Extends throughout the end of the planning horizon
- Standard heuristics used for production planning and capacity management
- Uses SNP PPMs/PDSs with bucketed capacity consumption requirements
PPDS Horizon Defined
PPDS horizon is solved with a variety of PPDS heuristics. You can manage this horizon with the planning book, or a variety of APO production planning transactions. The decisions made in this horizon are much more detailed and exacting than the SNP horizon. Considerations such as start and stop times, changeover sequences and pegging relationships are taken into consideration in the PPDS horizon. The level of master data required is much higher for this horizon to support the level of detail needed to support developing a specific plan.
At this stage, the setting for this horizon in the product master defines the end of the detailed scheduling horizon. Inside this horizon, the production planning jobs can automatically generate or reschedule orders. However, you can manually schedule orders outside of this horizon. The focus on this horizon is on the sequence and feasibility of an efficient schedule. Users working in this timeframe will be working closely with the plant floor to manage the orders and react to day-to-day issues on the plant floor. The ability to manage the supply at a detailed level is greatly increased with the features available inside the PPDS horizon, however, most are more performance intensive so it’s best to limit the horizon to the most useful time horizon for each individual business need.
PPDS Horizon Characteristics:
- Resource/Production line focused planning activities
- Short to medium term sequencing and scheduling on a resource
- Generally not bucketed capacity
- Continuous planning horizon
- Shows interactivity between orders and phases
- Multiple heuristic choices with many user-driven settings available
- Uses PPDS PPMs/PDSs with multiple interdependent phases
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