The primary goal of CTM scheduling is to create full or partial supplies= as to meet the demand in time. Due to capacity or material constraints, it’s possible that in-time supply plan creation isn’t feasible. In such scenarios, you can allow CTM to schedule late orders. There are two main options that are available to select the late demand strategies. You can define the late demand processing strategy in the CTM global customization. The two options for late demand strategy are the following:
Domino strategy
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Using the domino strategy, CTM will try to find an in-time and late solution for a given demand before planning for the next demand. Late fulfillment of a
demand can lead to late fulfillment of subsequent demands during demand pri-oritization. This may be the case if the capacity has already been exceeded.
Airline strategy
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Using the airline strategy, CTM will first try only in-time solutions for a given demand. If a demand can’t be fulfilled by the demand date, the subsequent demands are fulfilled first during demand prioritization. CTM doesn’t attempt to fulfill the late demand until the end of the demand list. The advantage of using this strategy is that late demand fulfillment doesn’t delay the fulfillment of subsequent demands.
If all demand elements have moved to the end of the demand prioritization list, CTM switches automatically to the domino strategy for the late demands.
The CTM demand attribute late demand frame (LDF) defines the allowed lateness of a demand. CTM will limit the creation of the orders per the LDF. CTM offers several options to define LDF as shown in Figure 4.21. The following options are available for defining LDF for each of the demand selected for planning:
Global LDF
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CTM global customization can be used to define a constant LDF for all product locations across all CTM profiles.
CTM profile-specific LDF
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If there are several CTM profiles used for planning different subsets of a model, then you can use the profile-specific LDF value using the CTM planning param-eter nLateShipGlobal with Value2 = <Number of Days of LDF>.
Demand-specific LDF
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Using the calculation profile assigned to the ATP rules, it’s possible to define a different LDF for each product location. This is mainly useful when working with products with different LDF requirements. In some scenarios, it’s required to have demand-dependent LDF. For example, when planning with sales orders and forecast orders, you want to have different LDFs for sales order and fore-cast orders.
Using the user exit APOBO020, it’s also possible to define a demand-specific LDF, which is calculated with reference to the demand date considering only the calen-dar days. If you use demand aggregation, then LDF is applied with respect to the new aggregated demand date instead of the original demand date.
Late Demand Frame
1. Global (Global Customization) 2. Profile Specific (CTM Profile) 3. Demand Specific (Calculation Profile)
1 2
3
Late Demand Frame Maintenance Options Figure 4.21
LDF can be displayed in the CTM demand simulation list and is used only for nor-mal demands. For safety stock demands, CTM calculates the allowed LDF for each of the virtual safety stock (SS) demands. You can also select a user-specific LDF for SS demands using the setting in the CTM profile. This is described in more detail in the next chapter.
Late Demand Scheduling Modes 4.5.1
Late demand scheduling in CTM is executed when the in-time solution with all possible sources of supplies doesn’t fulfill the required demand quantity. Schedul-ing for the remainSchedul-ing quantity is executed in LDF. There are three main schedulSchedul-ing options that are available for late demand planning in CTM (see Figure 4.22). You can select the late demand scheduling modes in the CTM profile using the settings available in the CTM profile.
CTM Late Demand Handling Modes Figure 4.22
The scheduling logic for all three scheduling modes is shown in Figure 4.23. The fi gure shows two sources of supplies (PPM/PDS), each with a maximum capacity of 10 units/day. The demand of 75 units can’t be fulfi lled in time. The scheduling logic for all three different scheduling modes is described in detail in the follow-ing sections.
10 10 10 5 R2
10 10 10 10 R1
Demand = 75 units Gradually Postpone Demands
10 10 10 5 R2
10 10 10 10 R1
Demand = 75 units
Keep Lateness to Minimum Forward Step
10 10 5 R2
10 10 10 10 10 R1
Demand = 75 units
Standard Procedure for Scheduling
CTM Late Demand Scheduling Modes Figure 4.23
Option 1: Standard Procedure for Scheduling
With this method for scheduling late demands, CTM gradually postpones the demand date by each day until a partial solution is found. At each day, CTM will check for all possible sourcing alternatives to fulfi ll the demand. Any partial sup-ply that can be created is saved. The daily search sequence is stopped as long as no new supply can be created. CTM will use the remaining quantity to determine the new possible date within LDF. Using the new date, CTM will apply the backward
scheduling mode to fulfill the remaining quantity. As shown in Figure 4.23, after Day 2, CTM doesn’t find any new supply due to a resource break. As a result, the remaining quantity of 35 units is used to determine the new date using the for-ward scheduling logic. CTM will select the highest priority SOS and find a possible date on Day 7. Using this new date, the remaining quantity is scheduled, causing suboptimal late supply using the second priority SOS.
Option 2: Gradually Postpone Demands
Using this option, you can search for the late solution with predefined intervals.
The intervals are defined using the Offset parameter in the CTM profile under the Special Strategies tab. As shown in Figure 4.23, the Offset value of 1 is used. The demand is fulfilled at each day until the complete solution is found within the LDF. In this option, the forward scheduling mode to determine the new possible date isn’t used, resulting in better use of all possible sources of supplies to create the late supplies as close to the demand date as possible. Using the offset of 1 day isn’t optimal for performance. It’s possible to define an offset of larger granularity to avoid performance issues. This won’t generate an optimal solution for products planned with short lead times and would cause much later supply creation. You have to select the late demand offset parameter while considering the lead times of the products and the allowed lateness for the demands.
Option 3: Keep Lateness to Minimum
With this option, CTM will schedule the orders to reduce the lateness as much as possible by using all of the possible sourcing alternatives. This method is similar to Option 2 but without any serious performance limitation.
Note that late demand scheduling is only applied for the primary demands selected for CTM planning. The dependent demands or secondary demands are always ful-filled in time.